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mylamour/ALLINSHELL.sh

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Advace SHELL example , parser from http://www.tldp.org/
Raw
ALLINSHELL.sh
This file has been truncated, but you can view the full file.
#!/bin/bash
echo "\$\$ outside of subshell = $$" # 9602
echo "\$BASH_SUBSHELL outside of subshell = $BASH_SUBSHELL" # 0
echo "\$BASHPID outside of subshell = $BASHPID" # 9602
echo
( echo "\$\$ inside of subshell = $$" # 9602
echo "\$BASH_SUBSHELL inside of subshell = $BASH_SUBSHELL" # 1
echo "\$BASHPID inside of subshell = $BASHPID" ) # 9603
# Note that $$ returns PID of parent process.
# Bash version info:
for n in 0 1 2 3 4 5
do
echo "BASH_VERSINFO[$n] = ${BASH_VERSINFO[$n]}"
done
# BASH_VERSINFO[0] = 3 # Major version no.
# BASH_VERSINFO[1] = 00 # Minor version no.
# BASH_VERSINFO[2] = 14 # Patch level.
# BASH_VERSINFO[3] = 1 # Build version.
# BASH_VERSINFO[4] = release # Release status.
# BASH_VERSINFO[5] = i386-redhat-linux-gnu # Architecture
# (same as $MACHTYPE).
xyz23 ()
{
echo "$FUNCNAME now executing." # xyz23 now executing.
}
xyz23
echo "FUNCNAME = $FUNCNAME" # FUNCNAME =
# Null value outside a function.
IFS="$(printf '\n\t')" # Per David Wheeler.
#!/bin/bash
# ifs.sh
var1="a+b+c"
var2="d-e-f"
var3="g,h,i"
IFS=+
# The plus sign will be interpreted as a separator.
echo $var1 # a b c
echo $var2 # d-e-f
echo $var3 # g,h,i
echo
IFS="-"
# The plus sign reverts to default interpretation.
# The minus sign will be interpreted as a separator.
echo $var1 # a+b+c
echo $var2 # d e f
echo $var3 # g,h,i
echo
IFS=","
# The comma will be interpreted as a separator.
# The minus sign reverts to default interpretation.
echo $var1 # a+b+c
echo $var2 # d-e-f
echo $var3 # g h i
echo
IFS=" "
# The space character will be interpreted as a separator.
# The comma reverts to default interpretation.
echo $var1 # a+b+c
echo $var2 # d-e-f
echo $var3 # g,h,i
# ======================================================== #
# However ...
# $IFS treats whitespace differently than other characters.
output_args_one_per_line()
{
for arg
do
echo "[$arg]"
done # ^ ^ Embed within brackets, for your viewing pleasure.
}
echo; echo "IFS=\" \""
echo "-------"
IFS=" "
var=" a b c "
# ^ ^^ ^^^
output_args_one_per_line $var # output_args_one_per_line `echo " a b c "`
# [a]
# [b]
# [c]
echo; echo "IFS=:"
echo "-----"
IFS=:
var=":a::b:c:::" # Same pattern as above,
# ^ ^^ ^^^ #+ but substituting ":" for " " ...
output_args_one_per_line $var
# []
# [a]
# []
# [b]
# [c]
# []
# []
# Note "empty" brackets.
# The same thing happens with the "FS" field separator in awk.
echo
exit
# *** BEGIN DEBUG BLOCK ***
last_cmd_arg=$_ # Save it.
echo "At line number $LINENO, variable \"v1\" = $v1"
echo "Last command argument processed = $last_cmd_arg"
# *** END DEBUG BLOCK ***
P4='$(read time junk < /proc/$$/schedstat; echo "@@@ $time @@@ " )'
# Per suggestion by Erik Brandsberg.
set -x
# Various commands follow ...
#!/bin/bash
E_WRONG_DIRECTORY=85
clear # Clear the screen.
TargetDirectory=/home/bozo/projects/GreatAmericanNovel
cd $TargetDirectory
echo "Deleting stale files in $TargetDirectory."
if [ "$PWD" != "$TargetDirectory" ]
then # Keep from wiping out wrong directory by accident.
echo "Wrong directory!"
echo "In $PWD, rather than $TargetDirectory!"
echo "Bailing out!"
exit $E_WRONG_DIRECTORY
fi
rm -rf *
rm .[A-Za-z0-9]* # Delete dotfiles.
# rm -f .[^.]* ..?* to remove filenames beginning with multiple dots.
# (shopt -s dotglob; rm -f *) will also work.
# Thanks, S.C. for pointing this out.
# A filename (`basename`) may contain all characters in the 0 - 255 range,
#+ except "/".
# Deleting files beginning with weird characters, such as -
#+ is left as an exercise. (Hint: rm ./-weirdname or rm -- -weirdname)
result=$? # Result of delete operations. If successful = 0.
echo
ls -al # Any files left?
echo "Done."
echo "Old files deleted in $TargetDirectory."
echo
# Various other operations here, as necessary.
exit $result
#!/bin/bash
# reply.sh
# REPLY is the default value for a 'read' command.
echo
echo -n "What is your favorite vegetable? "
read
echo "Your favorite vegetable is $REPLY."
# REPLY holds the value of last "read" if and only if
#+ no variable supplied.
echo
echo -n "What is your favorite fruit? "
read fruit
echo "Your favorite fruit is $fruit."
echo "but..."
echo "Value of \$REPLY is still $REPLY."
# $REPLY is still set to its previous value because
#+ the variable $fruit absorbed the new "read" value.
echo
exit 0
#!/bin/bash
TIME_LIMIT=10
INTERVAL=1
echo
echo "Hit Control-C to exit before $TIME_LIMIT seconds."
echo
while [ "$SECONDS" -le "$TIME_LIMIT" ]
do # $SECONDS is an internal shell variable.
if [ "$SECONDS" -eq 1 ]
then
units=second
else
units=seconds
fi
echo "This script has been running $SECONDS $units."
# On a slow or overburdened machine, the script may skip a count
#+ every once in a while.
sleep $INTERVAL
done
echo -e "\a" # Beep!
exit 0
# Works in scripts for Bash, versions 2.05b and later.
TMOUT=3 # Prompt times out at three seconds.
echo "What is your favorite song?"
echo "Quickly now, you only have $TMOUT seconds to answer!"
read song
if [ -z "$song" ]
then
song="(no answer)"
# Default response.
fi
echo "Your favorite song is $song."
#!/bin/bash
# timed-input.sh
# TMOUT=3 Also works, as of newer versions of Bash.
TIMER_INTERRUPT=14
TIMELIMIT=3 # Three seconds in this instance.
# May be set to different value.
PrintAnswer()
{
if [ "$answer" = TIMEOUT ]
then
echo $answer
else # Don't want to mix up the two instances.
echo "Your favorite veggie is $answer"
kill $! # Kills no-longer-needed TimerOn function
#+ running in background.
# $! is PID of last job running in background.
fi
}
TimerOn()
{
sleep $TIMELIMIT && kill -s 14 $$ &
# Waits 3 seconds, then sends sigalarm to script.
}
Int14Vector()
{
answer="TIMEOUT"
PrintAnswer
exit $TIMER_INTERRUPT
}
trap Int14Vector $TIMER_INTERRUPT
# Timer interrupt (14) subverted for our purposes.
echo "What is your favorite vegetable "
TimerOn
read answer
PrintAnswer
# Admittedly, this is a kludgy implementation of timed input.
# However, the "-t" option to "read" simplifies this task.
# See the "t-out.sh" script.
# However, what about timing not just single user input,
#+ but an entire script?
# If you need something really elegant ...
#+ consider writing the application in C or C++,
#+ using appropriate library functions, such as 'alarm' and 'setitimer.'
exit 0
#!/bin/bash
# timeout.sh
# Written by Stephane Chazelas,
#+ and modified by the document author.
INTERVAL=5 # timeout interval
timedout_read() {
timeout=$1
varname=$2
old_tty_settings=`stty -g`
stty -icanon min 0 time ${timeout}0
eval read $varname # or just read $varname
stty "$old_tty_settings"
# See man page for "stty."
}
echo; echo -n "What's your name? Quick! "
timedout_read $INTERVAL your_name
# This may not work on every terminal type.
# The maximum timeout depends on the terminal.
#+ (it is often 25.5 seconds).
echo
if [ ! -z "$your_name" ] # If name input before timeout ...
then
echo "Your name is $your_name."
else
echo "Timed out."
fi
echo
# The behavior of this script differs somewhat from "timed-input.sh."
# At each keystroke, the counter resets.
exit 0
#!/bin/bash
# t-out.sh [time-out]
# Inspired by a suggestion from "syngin seven" (thanks).
TIMELIMIT=4 # 4 seconds
read -t $TIMELIMIT variable <&1
# ^^^
# In this instance, "<&1" is needed for Bash 1.x and 2.x,
# but unnecessary for Bash 3+.
echo
if [ -z "$variable" ] # Is null?
then
echo "Timed out, variable still unset."
else
echo "variable = $variable"
fi
exit 0
#!/bin/bash
# am-i-root.sh: Am I root or not?
ROOT_UID=0 # Root has $UID 0.
if [ "$UID" -eq "$ROOT_UID" ] # Will the real "root" please stand up?
then
echo "You are root."
else
echo "You are just an ordinary user (but mom loves you just the same)."
fi
exit 0
# ============================================================= #
# Code below will not execute, because the script already exited.
# An alternate method of getting to the root of matters:
ROOTUSER_NAME=root
username=`id -nu` # Or... username=`whoami`
if [ "$username" = "$ROOTUSER_NAME" ]
then
echo "Rooty, toot, toot. You are root."
else
echo "You are just a regular fella."
fi
#!/bin/bash
# arglist.sh
# Invoke this script with several arguments, such as "one two three" ...
E_BADARGS=85
if [ ! -n "$1" ]
then
echo "Usage: `basename $0` argument1 argument2 etc."
exit $E_BADARGS
fi
echo
index=1 # Initialize count.
echo "Listing args with \"\$*\":"
for arg in "$*" # Doesn't work properly if "$*" isn't quoted.
do
echo "Arg #$index = $arg"
let "index+=1"
done # $* sees all arguments as single word.
echo "Entire arg list seen as single word."
echo
index=1 # Reset count.
# What happens if you forget to do this?
echo "Listing args with \"\$@\":"
for arg in "$@"
do
echo "Arg #$index = $arg"
let "index+=1"
done # $@ sees arguments as separate words.
echo "Arg list seen as separate words."
echo
index=1 # Reset count.
echo "Listing args with \$* (unquoted):"
for arg in $*
do
echo "Arg #$index = $arg"
let "index+=1"
done # Unquoted $* sees arguments as separate words.
echo "Arg list seen as separate words."
exit 0
#!/bin/bash
# Invoke with ./scriptname 1 2 3 4 5
echo "$@" # 1 2 3 4 5
shift
echo "$@" # 2 3 4 5
shift
echo "$@" # 3 4 5
# Each "shift" loses parameter $1.
# "$@" then contains the remaining parameters.
#!/bin/bash
# Erratic behavior of the "$*" and "$@" internal Bash variables,
#+ depending on whether or not they are quoted.
# Demonstrates inconsistent handling of word splitting and linefeeds.
set -- "First one" "second" "third:one" "" "Fifth: :one"
# Setting the script arguments, $1, $2, $3, etc.
echo
echo 'IFS unchanged, using "$*"'
c=0
for i in "$*" # quoted
do echo "$((c+=1)): [$i]" # This line remains the same in every instance.
# Echo args.
done
echo ---
echo 'IFS unchanged, using $*'
c=0
for i in $* # unquoted
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS unchanged, using "$@"'
c=0
for i in "$@"
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS unchanged, using $@'
c=0
for i in $@
do echo "$((c+=1)): [$i]"
done
echo ---
IFS=:
echo 'IFS=":", using "$*"'
c=0
for i in "$*"
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS=":", using $*'
c=0
for i in $*
do echo "$((c+=1)): [$i]"
done
echo ---
var=$*
echo 'IFS=":", using "$var" (var=$*)'
c=0
for i in "$var"
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS=":", using $var (var=$*)'
c=0
for i in $var
do echo "$((c+=1)): [$i]"
done
echo ---
var="$*"
echo 'IFS=":", using $var (var="$*")'
c=0
for i in $var
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS=":", using "$var" (var="$*")'
c=0
for i in "$var"
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS=":", using "$@"'
c=0
for i in "$@"
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS=":", using $@'
c=0
for i in $@
do echo "$((c+=1)): [$i]"
done
echo ---
var=$@
echo 'IFS=":", using $var (var=$@)'
c=0
for i in $var
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS=":", using "$var" (var=$@)'
c=0
for i in "$var"
do echo "$((c+=1)): [$i]"
done
echo ---
var="$@"
echo 'IFS=":", using "$var" (var="$@")'
c=0
for i in "$var"
do echo "$((c+=1)): [$i]"
done
echo ---
echo 'IFS=":", using $var (var="$@")'
c=0
for i in $var
do echo "$((c+=1)): [$i]"
done
echo
# Try this script with ksh or zsh -y.
exit 0
# This example script written by Stephane Chazelas,
#+ and slightly modified by the document author.
#!/bin/bash
# If $IFS set, but empty,
#+ then "$*" and "$@" do not echo positional params as expected.
mecho () # Echo positional parameters.
{
echo "$1,$2,$3";
}
IFS="" # Set, but empty.
set a b c # Positional parameters.
mecho "$*" # abc,,
# ^^
mecho $* # a,b,c
mecho $@ # a,b,c
mecho "$@" # a,b,c
# The behavior of $* and $@ when $IFS is empty depends
#+ on which Bash or sh version being run.
# It is therefore inadvisable to depend on this "feature" in a script.
# Thanks, Stephane Chazelas.
exit
LOG=$0.log
COMMAND1="sleep 100"
echo "Logging PIDs background commands for script: $0" &gt;&gt; "$LOG"
# So they can be monitored, and killed as necessary.
echo &gt;&gt; "$LOG"
# Logging commands.
echo -n "PID of \"$COMMAND1\": " &gt;&gt; "$LOG"
${COMMAND1} &
echo $! &gt;&gt; "$LOG"
# PID of "sleep 100": 1506
# Thank you, Jacques Lederer, for suggesting this.
possibly_hanging_job & { sleep ${TIMEOUT}; eval 'kill -9 $!' &&gt; /dev/null; }
# Forces completion of an ill-behaved program.
# Useful, for example, in init scripts.
# Thank you, Sylvain Fourmanoit, for this creative use of the "!" variable.
# This example by Matthew Sage.
# Used with permission.
TIMEOUT=30 # Timeout value in seconds
count=0
possibly_hanging_job & {
while ((count < TIMEOUT )); do
eval '[ ! -d "/proc/$!" ] && ((count = TIMEOUT))'
# /proc is where information about running processes is found.
# "-d" tests whether it exists (whether directory exists).
# So, we're waiting for the job in question to show up.
((count++))
sleep 1
done
eval '[ -d "/proc/$!" ] && kill -15 $!'
# If the hanging job is running, kill it.
}
# -------------------------------------------------------------- #
# However, this may not not work as specified if another process
#+ begins to run after the "hanging_job" . . .
# In such a case, the wrong job may be killed.
# Ariel Meragelman suggests the following fix.
TIMEOUT=30
count=0
# Timeout value in seconds
possibly_hanging_job & {
while ((count < TIMEOUT )); do
eval '[ ! -d "/proc/$lastjob" ] && ((count = TIMEOUT))'
lastjob=$!
((count++))
sleep 1
done
eval '[ -d "/proc/$lastjob" ] && kill -15 $lastjob'
}
exit
#!/bin/bash
echo $_ # /bin/bash
# Just called /bin/bash to run the script.
# Note that this will vary according to
#+ how the script is invoked.
du &gt;/dev/null # So no output from command.
echo $_ # du
ls -al &gt;/dev/null # So no output from command.
echo $_ # -al (last argument)
:
echo $_ # :</pre>]
[]
#!/bin/bash
# test-suite.sh
# A partial Bash compatibility test suite.
# Run this on your version of Bash, or some other shell.
default_option=FAIL # Tests below will fail unless . . .
echo
echo -n "Testing "
sleep 1; echo -n ". "
sleep 1; echo -n ". "
sleep 1; echo ". "
echo
# Double brackets
String="Double brackets supported?"
echo -n "Double brackets test: "
if [[ "$String" = "Double brackets supported?" ]]
then
echo "PASS"
else
echo "FAIL"
fi
# Double brackets and regex matching
String="Regex matching supported?"
echo -n "Regex matching: "
if [[ "$String" =~ R.....matching* ]]
then
echo "PASS"
else
echo "FAIL"
fi
# Arrays
test_arr=$default_option # FAIL
Array=( If supports arrays will print PASS )
test_arr=${Array[5]}
echo "Array test: $test_arr"
# Command Substitution
csub_test ()
{
echo "PASS"
}
test_csub=$default_option # FAIL
test_csub=$(csub_test)
echo "Command substitution test: $test_csub"
echo
# Completing this script is an exercise for the reader.
# Add to the above similar tests for double parentheses,
#+ brace expansion, process substitution, etc.
exit $?</pre>]
#!/bin/bash
ROOT_UID=0 # Only users with $UID 0 have root privileges.
E_NOTROOT=65
E_NOPARAMS=66
if [ "$UID" -ne "$ROOT_UID" ]
then
echo "Must be root to run this script."
# "Run along kid, it's past your bedtime."
exit $E_NOTROOT
fi
if [ -z "$1" ]
then
echo "Usage: `basename $0` find-string"
exit $E_NOPARAMS
fi
echo "Updating 'locate' database..."
echo "This may take a while."
updatedb /usr & # Must be run as root.
wait
# Don't run the rest of the script until 'updatedb' finished.
# You want the the database updated before looking up the file name.
locate $1
# Without the 'wait' command, in the worse case scenario,
#+ the script would exit while 'updatedb' was still running,
#+ leaving it as an orphan process.
exit 0
#!/bin/bash
# test.sh
ls -l &
echo "Done."
#!/bin/bash
# test.sh
ls -l &
echo "Done."
wait
#!/bin/bash
# self-destruct.sh
kill $$ # Script kills its own process here.
# Recall that "$$" is the script's PID.
echo "This line will not echo."
# Instead, the shell sends a "Terminated" message to stdout.
exit 0 # Normal exit? No!
# After this script terminates prematurely,
#+ what exit status does it return?
#
# sh self-destruct.sh
# echo $?
# 143
#
# 143 = 128 + 15
# TERM signal</pre>]
#!/bin/bash
# $RANDOM returns a different random integer at each invocation.
# Nominal range: 0 - 32767 (signed 16-bit integer).
MAXCOUNT=10
count=1
echo
echo "$MAXCOUNT random numbers:"
echo "-----------------"
while [ "$count" -le $MAXCOUNT ] # Generate 10 ($MAXCOUNT) random integers.
do
number=$RANDOM
echo $number
let "count += 1" # Increment count.
done
echo "-----------------"
# If you need a random int within a certain range, use the 'modulo' operator.
# This returns the remainder of a division operation.
RANGE=500
echo
number=$RANDOM
let "number %= $RANGE"
# ^^
echo "Random number less than $RANGE --- $number"
echo
# If you need a random integer greater than a lower bound,
#+ then set up a test to discard all numbers below that.
FLOOR=200
number=0 #initialize
while [ "$number" -le $FLOOR ]
do
number=$RANDOM
done
echo "Random number greater than $FLOOR --- $number"
echo
# Let's examine a simple alternative to the above loop, namely
# let "number = $RANDOM + $FLOOR"
# That would eliminate the while-loop and run faster.
# But, there might be a problem with that. What is it?
# Combine above two techniques to retrieve random number between two limits.
number=0 #initialize
while [ "$number" -le $FLOOR ]
do
number=$RANDOM
let "number %= $RANGE" # Scales $number down within $RANGE.
done
echo "Random number between $FLOOR and $RANGE --- $number"
echo
# Generate binary choice, that is, "true" or "false" value.
BINARY=2
T=1
number=$RANDOM
let "number %= $BINARY"
# Note that let "number &gt;&gt;= 14" gives a better random distribution
#+ (right shifts out everything except last binary digit).
if [ "$number" -eq $T ]
then
echo "TRUE"
else
echo "FALSE"
fi
echo
# Generate a toss of the dice.
SPOTS=6 # Modulo 6 gives range 0 - 5.
# Incrementing by 1 gives desired range of 1 - 6.
# Thanks, Paulo Marcel Coelho Aragao, for the simplification.
die1=0
die2=0
# Would it be better to just set SPOTS=7 and not add 1? Why or why not?
# Tosses each die separately, and so gives correct odds.
let "die1 = $RANDOM % $SPOTS +1" # Roll first one.
let "die2 = $RANDOM % $SPOTS +1" # Roll second one.
# Which arithmetic operation, above, has greater precedence --
#+ modulo (%) or addition (+)?
let "throw = $die1 + $die2"
echo "Throw of the dice = $throw"
echo
exit 0
#!/bin/bash
# pick-card.sh
# This is an example of choosing random elements of an array.
# Pick a card, any card.
Suites="Clubs
Diamonds
Hearts
Spades"
Denominations="2
3
4
5
6
7
8
9
10
Jack
Queen
King
Ace"
# Note variables spread over multiple lines.
suite=($Suites) # Read into array variable.
denomination=($Denominations)
num_suites=${#suite[*]} # Count how many elements.
num_denominations=${#denomination[*]}
echo -n "${denomination[$((RANDOM%num_denominations))]} of "
echo ${suite[$((RANDOM%num_suites))]}
# $bozo sh pick-cards.sh
# Jack of Clubs
# Thank you, "jipe," for pointing out this use of $RANDOM.
exit 0
#!/bin/bash
# brownian.sh
# Author: Mendel Cooper
# Reldate: 10/26/07
# License: GPL3
# ----------------------------------------------------------------
# This script models Brownian motion:
#+ the random wanderings of tiny particles in a fluid,
#+ as they are buffeted by random currents and collisions.
#+ This is colloquially known as the "Drunkard's Walk."
# It can also be considered as a stripped-down simulation of a
#+ Galton Board, a slanted board with a pattern of pegs,
#+ down which rolls a succession of marbles, one at a time.
#+ At the bottom is a row of slots or catch basins in which
#+ the marbles come to rest at the end of their journey.
# Think of it as a kind of bare-bones Pachinko game.
# As you see by running the script,
#+ most of the marbles cluster around the center slot.
#+ This is consistent with the expected binomial distribution.
# As a Galton Board simulation, the script
#+ disregards such parameters as
#+ board tilt-angle, rolling friction of the marbles,
#+ angles of impact, and elasticity of the pegs.
# To what extent does this affect the accuracy of the simulation?
# ----------------------------------------------------------------
PASSES=500 # Number of particle interactions / marbles.
ROWS=10 # Number of "collisions" (or horiz. peg rows).
RANGE=3 # 0 - 2 output range from $RANDOM.
POS=0 # Left/right position.
RANDOM=$$ # Seeds the random number generator from PID
#+ of script.
declare -a Slots # Array holding cumulative results of passes.
NUMSLOTS=21 # Number of slots at bottom of board.
Initialize_Slots () { # Zero out all elements of the array.
for i in $( seq $NUMSLOTS )
do
Slots[$i]=0
done
echo # Blank line at beginning of run.
}
Show_Slots () {
echo; echo
echo -n " "
for i in $( seq $NUMSLOTS ) # Pretty-print array elements.
do
printf "%3d" ${Slots[$i]} # Allot three spaces per result.
done
echo # Row of slots:
echo " |__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|"
echo " ||"
echo # Note that if the count within any particular slot exceeds 99,
#+ it messes up the display.
# Running only(!) 500 passes usually avoids this.
}
Move () { # Move one unit right / left, or stay put.
Move=$RANDOM # How random is $RANDOM? Well, let's see ...
let "Move %= RANGE" # Normalize into range of 0 - 2.
case "$Move" in
0 ) ;; # Do nothing, i.e., stay in place.
1 ) ((POS--));; # Left.
2 ) ((POS++));; # Right.
* ) echo -n "Error ";; # Anomaly! (Should never occur.)
esac
}
Play () { # Single pass (inner loop).
i=0
while [ "$i" -lt "$ROWS" ] # One event per row.
do
Move
((i++));
done
SHIFT=11 # Why 11, and not 10?
let "POS += $SHIFT" # Shift "zero position" to center.
(( Slots[$POS]++ )) # DEBUG: echo $POS
# echo -n "$POS "
}
Run () { # Outer loop.
p=0
while [ "$p" -lt "$PASSES" ]
do
Play
(( p++ ))
POS=0 # Reset to zero. Why?
done
}
# --------------
# main ()
Initialize_Slots
Run
Show_Slots
# --------------
exit $?
# Exercises:
# ---------
# 1) Show the results in a vertical bar graph, or as an alternative,
#+ a scattergram.
# 2) Alter the script to use /dev/urandom instead of $RANDOM.
# Will this make the results more random?
# 3) Provide some sort of "animation" or graphic output
# for each marble played.
# Generate random number between 6 and 30.
rnumber=$((RANDOM%25+6))
# Generate random number in the same 6 - 30 range,
#+ but the number must be evenly divisible by 3.
rnumber=$(((RANDOM%30/3+1)*3))
# Note that this will not work all the time.
# It fails if $RANDOM%30 returns 0.
# Frank Wang suggests the following alternative:
rnumber=$(( RANDOM%27/3*3+6 ))
rnumber=$(((RANDOM%(max-min+divisibleBy))/divisibleBy*divisibleBy+min))
#!/bin/bash
# random-between.sh
# Random number between two specified values.
# Script by Bill Gradwohl, with minor modifications by the document author.
# Corrections in lines 187 and 189 by Anthony Le Clezio.
# Used with permission.
randomBetween() {
# Generates a positive or negative random number
#+ between $min and $max
#+ and divisible by $divisibleBy.
# Gives a "reasonably random" distribution of return values.
#
# Bill Gradwohl - Oct 1, 2003
syntax() {
# Function embedded within function.
echo
echo "Syntax: randomBetween [min] [max] [multiple]"
echo
echo -n "Expects up to 3 passed parameters, "
echo "but all are completely optional."
echo "min is the minimum value"
echo "max is the maximum value"
echo -n "multiple specifies that the answer must be "
echo "a multiple of this value."
echo " i.e. answer must be evenly divisible by this number."
echo
echo "If any value is missing, defaults area supplied as: 0 32767 1"
echo -n "Successful completion returns 0, "
echo "unsuccessful completion returns"
echo "function syntax and 1."
echo -n "The answer is returned in the global variable "
echo "randomBetweenAnswer"
echo -n "Negative values for any passed parameter are "
echo "handled correctly."
}
local min=${1:-0}
local max=${2:-32767}
local divisibleBy=${3:-1}
# Default values assigned, in case parameters not passed to function.
local x
local spread
# Let's make sure the divisibleBy value is positive.
[ ${divisibleBy} -lt 0 ] && divisibleBy=$((0-divisibleBy))
# Sanity check.
if [ $# -gt 3 -o ${divisibleBy} -eq 0 -o ${min} -eq ${max} ]; then
syntax
return 1
fi
# See if the min and max are reversed.
if [ ${min} -gt ${max} ]; then
# Swap them.
x=${min}
min=${max}
max=${x}
fi
# If min is itself not evenly divisible by $divisibleBy,
#+ then fix the min to be within range.
if [ $((min/divisibleBy*divisibleBy)) -ne ${min} ]; then
if [ ${min} -lt 0 ]; then
min=$((min/divisibleBy*divisibleBy))
else
min=$((((min/divisibleBy)+1)*divisibleBy))
fi
fi
# If max is itself not evenly divisible by $divisibleBy,
#+ then fix the max to be within range.
if [ $((max/divisibleBy*divisibleBy)) -ne ${max} ]; then
if [ ${max} -lt 0 ]; then
max=$((((max/divisibleBy)-1)*divisibleBy))
else
max=$((max/divisibleBy*divisibleBy))
fi
fi
# ---------------------------------------------------------------------
# Now, to do the real work.
# Note that to get a proper distribution for the end points,
#+ the range of random values has to be allowed to go between
#+ 0 and abs(max-min)+divisibleBy, not just abs(max-min)+1.
# The slight increase will produce the proper distribution for the
#+ end points.
# Changing the formula to use abs(max-min)+1 will still produce
#+ correct answers, but the randomness of those answers is faulty in
#+ that the number of times the end points ($min and $max) are returned
#+ is considerably lower than when the correct formula is used.
# ---------------------------------------------------------------------
spread=$((max-min))
# Omair Eshkenazi points out that this test is unnecessary,
#+ since max and min have already been switched around.
[ ${spread} -lt 0 ] && spread=$((0-spread))
let spread+=divisibleBy
randomBetweenAnswer=$(((RANDOM%spread)/divisibleBy*divisibleBy+min))
return 0
# However, Paulo Marcel Coelho Aragao points out that
#+ when $max and $min are not divisible by $divisibleBy,
#+ the formula fails.
#
# He suggests instead the following formula:
# rnumber = $(((RANDOM%(max-min+1)+min)/divisibleBy*divisibleBy))
}
# Let's test the function.
min=-14
max=20
divisibleBy=3
# Generate an array of expected answers and check to make sure we get
#+ at least one of each answer if we loop long enough.
declare -a answer
minimum=${min}
maximum=${max}
if [ $((minimum/divisibleBy*divisibleBy)) -ne ${minimum} ]; then
if [ ${minimum} -lt 0 ]; then
minimum=$((minimum/divisibleBy*divisibleBy))
else
minimum=$((((minimum/divisibleBy)+1)*divisibleBy))
fi
fi
# If max is itself not evenly divisible by $divisibleBy,
#+ then fix the max to be within range.
if [ $((maximum/divisibleBy*divisibleBy)) -ne ${maximum} ]; then
if [ ${maximum} -lt 0 ]; then
maximum=$((((maximum/divisibleBy)-1)*divisibleBy))
else
maximum=$((maximum/divisibleBy*divisibleBy))
fi
fi
# We need to generate only positive array subscripts,
#+ so we need a displacement that that will guarantee
#+ positive results.
disp=$((0-minimum))
for ((i=${minimum}; i<=${maximum}; i+=divisibleBy)); do
answer[i+disp]=0
done
# Now loop a large number of times to see what we get.
loopIt=1000 # The script author suggests 100000,
#+ but that takes a good long while.
for ((i=0; i<${loopIt}; ++i)); do
# Note that we are specifying min and max in reversed order here to
#+ make the function correct for this case.
randomBetween ${max} ${min} ${divisibleBy}
# Report an error if an answer is unexpected.
[ ${randomBetweenAnswer} -lt ${min} -o ${randomBetweenAnswer} -gt ${max} ] \
&& echo MIN or MAX error - ${randomBetweenAnswer}!
[ $((randomBetweenAnswer%${divisibleBy})) -ne 0 ] \
&& echo DIVISIBLE BY error - ${randomBetweenAnswer}!
# Store the answer away statistically.
answer[randomBetweenAnswer+disp]=$((answer[randomBetweenAnswer+disp]+1))
done
# Let's check the results
for ((i=${minimum}; i<=${maximum}; i+=divisibleBy)); do
[ ${answer[i+disp]} -eq 0 ] \
&& echo "We never got an answer of $i." \
|| echo "${i} occurred ${answer[i+disp]} times."
done
exit 0
#!/bin/bash
# How random is RANDOM?
RANDOM=$$ # Reseed the random number generator using script process ID.
PIPS=6 # A die has 6 pips.
MAXTHROWS=600 # Increase this if you have nothing better to do with your time.
throw=0 # Number of times the dice have been cast.
ones=0 # Must initialize counts to zero,
twos=0 #+ since an uninitialized variable is null, NOT zero.
threes=0
fours=0
fives=0
sixes=0
print_result ()
{
echo
echo "ones = $ones"
echo "twos = $twos"
echo "threes = $threes"
echo "fours = $fours"
echo "fives = $fives"
echo "sixes = $sixes"
echo
}
update_count()
{
case "$1" in
0) ((ones++));; # Since a die has no "zero", this corresponds to 1.
1) ((twos++));; # And this to 2.
2) ((threes++));; # And so forth.
3) ((fours++));;
4) ((fives++));;
5) ((sixes++));;
esac
}
echo
while [ "$throw" -lt "$MAXTHROWS" ]
do
let "die1 = RANDOM % $PIPS"
update_count $die1
let "throw += 1"
done
print_result
exit $?
# The scores should distribute evenly, assuming RANDOM is random.
# With $MAXTHROWS at 600, all should cluster around 100,
#+ plus-or-minus 20 or so.
#
# Keep in mind that RANDOM is a ***pseudorandom*** generator,
#+ and not a spectacularly good one at that.
# Randomness is a deep and complex subject.
# Sufficiently long "random" sequences may exhibit
#+ chaotic and other "non-random" behavior.
# Exercise (easy):
# ---------------
# Rewrite this script to flip a coin 1000 times.
# Choices are "HEADS" and "TAILS."
#!/bin/bash
# seeding-random.sh: Seeding the RANDOM variable.
# v 1.1, reldate 09 Feb 2013
MAXCOUNT=25 # How many numbers to generate.
SEED=
random_numbers ()
{
local count=0
local number
while [ "$count" -lt "$MAXCOUNT" ]
do
number=$RANDOM
echo -n "$number "
let "count++"
done
}
echo; echo
SEED=1
RANDOM=$SEED # Setting RANDOM seeds the random number generator.
echo "Random seed = $SEED"
random_numbers
RANDOM=$SEED # Same seed for RANDOM . . .
echo; echo "Again, with same random seed ..."
echo "Random seed = $SEED"
random_numbers # . . . reproduces the exact same number series.
#
# When is it useful to duplicate a "random" series?
echo; echo
SEED=2
RANDOM=$SEED # Trying again, but with a different seed . . .
echo "Random seed = $SEED"
random_numbers # . . . gives a different number series.
echo; echo
# RANDOM=$$ seeds RANDOM from process id of script.
# It is also possible to seed RANDOM from 'time' or 'date' commands.
# Getting fancy...
SEED=$(head -1 /dev/urandom | od -N 1 | awk '{ print $2 }'| sed s/^0*//)
# Pseudo-random output fetched
#+ from /dev/urandom (system pseudo-random device-file),
#+ then converted to line of printable (octal) numbers by "od",
#+ then "awk" retrieves just one number for SEED,
#+ finally "sed" removes any leading zeros.
RANDOM=$SEED
echo "Random seed = $SEED"
random_numbers
echo; echo
exit 0
#!/bin/bash
# random2.sh: Returns a pseudorandom number in the range 0 - 1,
#+ to 6 decimal places. For example: 0.822725
# Uses the awk rand() function.
AWKSCRIPT=' { srand(); print rand() } '
# Command(s)/parameters passed to awk
# Note that srand() reseeds awk's random number generator.
echo -n "Random number between 0 and 1 = "
echo | awk "$AWKSCRIPT"
# What happens if you leave out the 'echo'?
exit 0
# Exercises:
# ---------
# 1) Using a loop construct, print out 10 different random numbers.
# (Hint: you must reseed the srand() function with a different seed
#+ in each pass through the loop. What happens if you omit this?)
# 2) Using an integer multiplier as a scaling factor, generate random numbers
#+ in the range of 10 to 100.
# 3) Same as exercise #2, above, but generate random integers this time.</pre>]
#!/bin/bash
# history.sh
# A (vain) attempt to use the 'history' command in a script.
history # No output.
var=$(history); echo "$var" # $var is empty.
# History commands are, by default, disabled within a script.
# However, as dhw points out,
#+ set -o history
#+ enables the history mechanism.
set -o history
var=$(history); echo "$var" # 1 var=$(history)</pre>]
[]
#!/bin/bash
LIMIT=19 # Upper limit
echo
echo "Printing Numbers 1 through 20 (but not 3 and 11)."
a=0
while [ $a -le "$LIMIT" ]
do
a=$(($a+1))
if [ "$a" -eq 3 ] || [ "$a" -eq 11 ] # Excludes 3 and 11.
then
continue # Skip rest of this particular loop iteration.
fi
echo -n "$a " # This will not execute for 3 and 11.
done
# Exercise:
# Why does the loop print up to 20?
echo; echo
echo Printing Numbers 1 through 20, but something happens after 2.
##################################################################
# Same loop, but substituting 'break' for 'continue'.
a=0
while [ "$a" -le "$LIMIT" ]
do
a=$(($a+1))
if [ "$a" -gt 2 ]
then
break # Skip entire rest of loop.
fi
echo -n "$a "
done
echo; echo; echo
exit 0
#!/bin/bash
# break-levels.sh: Breaking out of loops.
# "break N" breaks out of N level loops.
for outerloop in 1 2 3 4 5
do
echo -n "Group $outerloop: "
# --------------------------------------------------------
for innerloop in 1 2 3 4 5
do
echo -n "$innerloop "
if [ "$innerloop" -eq 3 ]
then
break # Try break 2 to see what happens.
# ("Breaks" out of both inner and outer loops.)
fi
done
# --------------------------------------------------------
echo
done
echo
exit 0
#!/bin/bash
# The "continue N" command, continuing at the Nth level loop.
for outer in I II III IV V # outer loop
do
echo; echo -n "Group $outer: "
# --------------------------------------------------------------------
for inner in 1 2 3 4 5 6 7 8 9 10 # inner loop
do
if [[ "$inner" -eq 7 && "$outer" = "III" ]]
then
continue 2 # Continue at loop on 2nd level, that is "outer loop".
# Replace above line with a simple "continue"
# to see normal loop behavior.
fi
echo -n "$inner " # 7 8 9 10 will not echo on "Group III."
done
# --------------------------------------------------------------------
done
echo; echo
# Exercise:
# Come up with a meaningful use for "continue N" in a script.
exit 0
# Albert Reiner gives an example of how to use "continue N":
# ---------------------------------------------------------
# Suppose I have a large number of jobs that need to be run, with
#+ any data that is to be treated in files of a given name pattern
#+ in a directory. There are several machines that access
#+ this directory, and I want to distribute the work over these
#+ different boxen.
# Then I usually nohup something like the following on every box:
while true
do
for n in .iso.*
do
[ "$n" = ".iso.opts" ] && continue
beta=${n#.iso.}
[ -r .Iso.$beta ] && continue
[ -r .lock.$beta ] && sleep 10 && continue
lockfile -r0 .lock.$beta || continue
echo -n "$beta: " `date`
run-isotherm $beta
date
ls -alF .Iso.$beta
[ -r .Iso.$beta ] && rm -f .lock.$beta
continue 2
done
break
done
exit 0
# The details, in particular the sleep N, are particular to my
#+ application, but the general pattern is:
while true
do
for job in {pattern}
do
{job already done or running} && continue
{mark job as running, do job, mark job as done}
continue 2
done
break # Or something like `sleep 600' to avoid termination.
done
# This way the script will stop only when there are no more jobs to do
#+ (including jobs that were added during runtime). Through the use
#+ of appropriate lockfiles it can be run on several machines
#+ concurrently without duplication of calculations [which run a couple
#+ of hours in my case, so I really want to avoid this]. Also, as search
#+ always starts again from the beginning, one can encode priorities in
#+ the file names. Of course, one could also do this without `continue 2',
#+ but then one would have to actually check whether or not some job
#+ was done (so that we should immediately look for the next job) or not
#+ (in which case we terminate or sleep for a long time before checking
#+ for a new job).</pre>]
[]
#!/bin/bash
MAX=10000
for((nr=1; nr<$MAX; nr++))
do
let "t1 = nr % 5"
if [ "$t1" -ne 3 ]
then
continue
fi
let "t2 = nr % 7"
if [ "$t2" -ne 4 ]
then
continue
fi
let "t3 = nr % 9"
if [ "$t3" -ne 5 ]
then
continue
fi
break # What happens when you comment out this line? Why?
done
echo "Number = $nr"
exit 0
#!/bin/bash
DIRNAME=/usr/bin
FILETYPE="shell script"
LOGFILE=logfile
file "$DIRNAME"/* | fgrep "$FILETYPE" | tee $LOGFILE | wc -l
exit 0
#!/bin/bash
# Author: Nathan Coulter
# This code is released to the public domain.
# The author gave permission to use this code snippet in the ABS Guide.
find -maxdepth 1 -type f -printf '%f\000' | {
while read -d $'\000'; do
mv "$REPLY" "$(date -d "$(stat -c '%y' "$REPLY") " '+%Y%m%d%H%M%S'
)-$REPLY"
done
}
# Warning: Test-drive this script in a "scratch" directory.
# It will somehow affect all the files there.
while read LINE
do
echo $LINE
done < `tail -f /var/log/messages`
export SUM=0; for f in $(find src -name "*.java");
do export SUM=$(($SUM + $(wc -l $f | awk '{ print $1 }'))); done; echo $SUM</pre>]
[]
#!/bin/bash
# ex62.sh: Global and local variables inside a function.
func ()
{
local loc_var=23 # Declared as local variable.
echo # Uses the 'local' builtin.
echo "\"loc_var\" in function = $loc_var"
global_var=999 # Not declared as local.
# Therefore, defaults to global.
echo "\"global_var\" in function = $global_var"
}
func
# Now, to see if local variable "loc_var" exists outside the function.
echo
echo "\"loc_var\" outside function = $loc_var"
# $loc_var outside function =
# No, $loc_var not visible globally.
echo "\"global_var\" outside function = $global_var"
# $global_var outside function = 999
# $global_var is visible globally.
echo
exit 0
# In contrast to C, a Bash variable declared inside a function
#+ is local ONLY if declared as such.
#!/bin/bash
func ()
{
global_var=37 # Visible only within the function block
#+ before the function has been called.
} # END OF FUNCTION
echo "global_var = $global_var" # global_var =
# Function "func" has not yet been called,
#+ so $global_var is not visible here.
func
echo "global_var = $global_var" # global_var = 37
# Has been set by function call.
#!/bin/bash
echo "==OUTSIDE Function (global)=="
t=$(exit 1)
echo $? # 1
# As expected.
echo
function0 ()
{
echo "==INSIDE Function=="
echo "Global"
t0=$(exit 1)
echo $? # 1
# As expected.
echo
echo "Local declared & assigned in same command."
local t1=$(exit 1)
echo $? # 0
# Unexpected!
# Apparently, the variable assignment takes place before
#+ the local declaration.
#+ The return value is for the latter.
echo
echo "Local declared, then assigned (separate commands)."
local t2
t2=$(exit 1)
echo $? # 1
# As expected.
}
function0
#!/bin/bash
# recursion-demo.sh
# Demonstration of recursion.
RECURSIONS=9 # How many times to recurse.
r_count=0 # Must be global. Why?
recurse ()
{
var="$1"
while [ "$var" -ge 0 ]
do
echo "Recursion count = "$r_count" +-+ \$var = "$var""
(( var-- )); (( r_count++ ))
recurse "$var" # Function calls itself (recurses)
done #+ until what condition is met?
}
recurse $RECURSIONS
exit $?
#!/bin/bash
# recursion-def.sh
# A script that defines "recursion" in a rather graphic way.
RECURSIONS=10
r_count=0
sp=" "
define_recursion ()
{
((r_count++))
sp="$sp"" "
echo -n "$sp"
echo "\"The act of recurring ... \"" # Per 1913 Webster's dictionary.
while [ $r_count -le $RECURSIONS ]
do
define_recursion
done
}
echo
echo "Recursion: "
define_recursion
echo
exit $?
#!/bin/bash
# factorial
# ---------
# Does bash permit recursion?
# Well, yes, but...
# It's so slow that you gotta have rocks in your head to try it.
MAX_ARG=5
E_WRONG_ARGS=85
E_RANGE_ERR=86
if [ -z "$1" ]
then
echo "Usage: `basename $0` number"
exit $E_WRONG_ARGS
fi
if [ "$1" -gt $MAX_ARG ]
then
echo "Out of range ($MAX_ARG is maximum)."
# Let's get real now.
# If you want greater range than this,
#+ rewrite it in a Real Programming Language.
exit $E_RANGE_ERR
fi
fact ()
{
local number=$1
# Variable "number" must be declared as local,
#+ otherwise this doesn't work.
if [ "$number" -eq 0 ]
then
factorial=1 # Factorial of 0 = 1.
else
let "decrnum = number - 1"
fact $decrnum # Recursive function call (the function calls itself).
let "factorial = $number * $?"
fi
return $factorial
}
fact $1
echo "Factorial of $1 is $?."
exit 0
#!/bin/bash
function1 ()
{
local func1var=20
echo "Within function1, \$func1var = $func1var."
function2
}
function2 ()
{
echo "Within function2, \$func1var = $func1var."
}
function1
exit 0
# Output of the script:
# Within function1, $func1var = 20.
# Within function2, $func1var = 20.
#!/bin/bash
# Warning: Running this script could possibly lock up your system!
# If you're lucky, it will segfault before using up all available memory.
recursive_function ()
{
echo "$1" # Makes the function do something, and hastens the segfault.
(( $1 < $2 )) && recursive_function $(( $1 + 1 )) $2;
# As long as 1st parameter is less than 2nd,
#+ increment 1st and recurse.
}
recursive_function 1 50000 # Recurse 50,000 levels!
# Most likely segfaults (depending on stack size, set by ulimit -m).
# Recursion this deep might cause even a C program to segfault,
#+ by using up all the memory allotted to the stack.
echo "This will probably not print."
exit 0 # This script will not exit normally.
# Thanks, Stéphane Chazelas.</pre>]
[]
[]
chgrp --recursive dunderheads *.data
# The "dunderheads" group will now own all the "*.data" files
#+ all the way down the $PWD directory tree (that's what "recursive" means).
#!/bin/bash
# Some commands.
sudo cp /root/secretfile /home/bozo/secret
# Some more commands.
#!/bin/bash
# setnew-password.sh: For demonstration purposes only.
# Not a good idea to actually run this script.
# This script must be run as root.
ROOT_UID=0 # Root has $UID 0.
E_WRONG_USER=65 # Not root?
E_NOSUCHUSER=70
SUCCESS=0
if [ "$UID" -ne "$ROOT_UID" ]
then
echo; echo "Only root can run this script."; echo
exit $E_WRONG_USER
else
echo
echo "You should know better than to run this script, root."
echo "Even root users get the blues... "
echo
fi
username=bozo
NEWPASSWORD=security_violation
# Check if bozo lives here.
grep -q "$username" /etc/passwd
if [ $? -ne $SUCCESS ]
then
echo "User $username does not exist."
echo "No password changed."
exit $E_NOSUCHUSER
fi
echo "$NEWPASSWORD" | passwd --stdin "$username"
# The '--stdin' option to 'passwd' permits
#+ getting a new password from stdin (or a pipe).
echo; echo "User $username's password changed!"
# Using the 'passwd' command in a script is dangerous.
exit 0
#!/bin/bash
# erase.sh: Using "stty" to set an erase character when reading input.
echo -n "What is your name? "
read name # Try to backspace
#+ to erase characters of input.
# Problems?
echo "Your name is $name."
stty erase '#' # Set "hashmark" (#) as erase character.
echo -n "What is your name? "
read name # Use # to erase last character typed.
echo "Your name is $name."
exit 0
# Even after the script exits, the new key value remains set.
# Exercise: How would you reset the erase character to the default value?
#!/bin/bash
# secret-pw.sh: secret password
echo
echo -n "Enter password "
read passwd
echo "password is $passwd"
echo -n "If someone had been looking over your shoulder, "
echo "your password would have been compromised."
echo && echo # Two line-feeds in an "and list."
stty -echo # Turns off screen echo.
# May also be done with
# read -sp passwd
# A big Thank You to Leigh James for pointing this out.
echo -n "Enter password again "
read passwd
echo
echo "password is $passwd"
echo
stty echo # Restores screen echo.
exit 0
# Do an 'info stty' for more on this useful-but-tricky command.
#!/bin/bash
# keypress.sh: Detect a user keypress ("hot keys").
echo
old_tty_settings=$(stty -g) # Save old settings (why?).
stty -icanon
Keypress=$(head -c1) # or $(dd bs=1 count=1 2&gt; /dev/null)
# on non-GNU systems
echo
echo "Key pressed was \""$Keypress"\"."
echo
stty "$old_tty_settings" # Restore old settings.
# Thanks, Stephane Chazelas.
exit 0
setterm -bold on
echo bold hello
setterm -bold off
echo normal hello
# From /etc/pcmcia/serial script:
IRQ=`setserial /dev/$DEVICE | sed -e 's/.*IRQ: //'`
setserial /dev/$DEVICE irq 0 ; setserial /dev/$DEVICE irq $IRQ
#! /bin/sh
## Duplicate DaveG's ident-scan thingie using netcat. Oooh, he'll be p*ssed.
## Args: target port [port port port ...]
## Hose stdout _and_ stderr together.
##
## Advantages: runs slower than ident-scan, giving remote inetd less cause
##+ for alarm, and only hits the few known daemon ports you specify.
## Disadvantages: requires numeric-only port args, the output sleazitude,
##+ and won't work for r-services when coming from high source ports.
# Script author: Hobbit <hobbit@avian.org&gt;
# Used in ABS Guide with permission.
# ---------------------------------------------------
E_BADARGS=65 # Need at least two args.
TWO_WINKS=2 # How long to sleep.
THREE_WINKS=3
IDPORT=113 # Authentication "tap ident" port.
RAND1=999
RAND2=31337
TIMEOUT0=9
TIMEOUT1=8
TIMEOUT2=4
# ---------------------------------------------------
case "${2}" in
"" ) echo "Need HOST and at least one PORT." ; exit $E_BADARGS ;;
esac
# Ping 'em once and see if they *are* running identd.
nc -z -w $TIMEOUT0 "$1" $IDPORT || \
{ echo "Oops, $1 isn't running identd." ; exit 0 ; }
# -z scans for listening daemons.
# -w $TIMEOUT = How long to try to connect.
# Generate a randomish base port.
RP=`expr $$ % $RAND1 + $RAND2`
TRG="$1"
shift
while test "$1" ; do
nc -v -w $TIMEOUT1 -p ${RP} "$TRG" ${1} < /dev/null &gt; /dev/null &
PROC=$!
sleep $THREE_WINKS
echo "${1},${RP}" | nc -w $TIMEOUT2 -r "$TRG" $IDPORT 2&gt;&1
sleep $TWO_WINKS
# Does this look like a lamer script or what . . . ?
# ABS Guide author comments: "Ain't really all that bad . . .
#+ kinda clever, actually."
kill -HUP $PROC
RP=`expr ${RP} + 1`
shift
done
exit $?
# Notes:
# -----
# Try commenting out line 30 and running this script
#+ with "localhost.localdomain 25" as arguments.
# For more of Hobbit's 'nc' example scripts,
#+ look in the documentation:
#+ the /usr/share/doc/nc-X.XX/scripts directory.
echo clone | nc thunk.org 5000 &gt; e2fsprogs.dat
#!/bin/bash
# fileinfo2.sh
# Per suggestion of Joël Bourquard and . . .
# http://www.linuxquestions.org/questions/showthread.php?t=410766
FILENAME=testfile.txt
file_name=$(stat -c%n "$FILENAME") # Same as "$FILENAME" of course.
file_owner=$(stat -c%U "$FILENAME")
file_size=$(stat -c%s "$FILENAME")
# Certainly easier than using "ls -l $FILENAME"
#+ and then parsing with sed.
file_inode=$(stat -c%i "$FILENAME")
file_type=$(stat -c%F "$FILENAME")
file_access_rights=$(stat -c%A "$FILENAME")
echo "File name: $file_name"
echo "File owner: $file_owner"
echo "File size: $file_size"
echo "File inode: $file_inode"
echo "File type: $file_type"
echo "File access rights: $file_access_rights"
exit 0
sh fileinfo2.sh
File name: testfile.txt
File owner: bozo
File size: 418
File inode: 1730378
File type: regular file
File access rights: -rw-rw-r--
logger Experiencing instability in network connection at 23:10, 05/21.
# Now, do a 'tail /var/log/messages'.
logger -t $0 -i Logging at line "$LINENO".
# The "-t" option specifies the tag for the logger entry.
# The "-i" option records the process ID.
# tail /var/log/message
# ...
# Jul 7 20:48:58 localhost ./test.sh[1712]: Logging at line 3.
#!/bin/bash
# kill-process.sh
NOPROCESS=2
process=xxxyyyzzz # Use nonexistent process.
# For demo purposes only...
# ... don't want to actually kill any actual process with this script.
#
# If, for example, you wanted to use this script to logoff the Internet,
# process=pppd
t=`pidof $process` # Find pid (process id) of $process.
# The pid is needed by 'kill' (can't 'kill' by program name).
if [ -z "$t" ] # If process not present, 'pidof' returns null.
then
echo "Process $process was not running."
echo "Nothing killed."
exit $NOPROCESS
fi
kill $t # May need 'kill -9' for stubborn process.
# Need a check here to see if process allowed itself to be killed.
# Perhaps another " t=`pidof $process` " or ...
# This entire script could be replaced by
# kill $(pidof -x process_name)
# or
# killall process_name
# but it would not be as instructive.
exit 0
#!/bin/bash
SERVER=$HOST # localhost.localdomain (127.0.0.1).
PORT_NUMBER=25 # SMTP port.
nmap $SERVER | grep -w "$PORT_NUMBER" # Is that particular port open?
# grep -w matches whole words only,
#+ so this wouldn't match port 1025, for example.
exit 0
# 25/tcp open smtp
# Code snippets from /etc/rc.d/init.d/network
# ...
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
[ -x /sbin/ifconfig ] || exit 0
# ...
for i in $interfaces ; do
if ifconfig $i 2&gt;/dev/null | grep -q "UP" &gt;/dev/null 2&gt;&1 ; then
action "Shutting down interface $i: " ./ifdown $i boot
fi
# The GNU-specific "-q" option to "grep" means "quiet", i.e.,
#+ producing no output.
# Redirecting output to /dev/null is therefore not strictly necessary.
# ...
echo "Currently active devices:"
echo `/sbin/ifconfig | grep ^[a-z] | awk '{print $1}'`
# ^^^^^ should be quoted to prevent globbing.
# The following also work.
# echo $(/sbin/ifconfig | awk '/^[a-z]/ { print $1 })'
# echo $(/sbin/ifconfig | sed -e 's/ .*//')
# Thanks, S.C., for additional comments.
#!/bin/bash
# Script by Juan Nicolas Ruiz
# Used with his kind permission.
# Setting up (and stopping) a GRE tunnel.
# --- start-tunnel.sh ---
LOCAL_IP="192.168.1.17"
REMOTE_IP="10.0.5.33"
OTHER_IFACE="192.168.0.100"
REMOTE_NET="192.168.3.0/24"
/sbin/ip tunnel add netb mode gre remote $REMOTE_IP \
local $LOCAL_IP ttl 255
/sbin/ip addr add $OTHER_IFACE dev netb
/sbin/ip link set netb up
/sbin/ip route add $REMOTE_NET dev netb
exit 0 #############################################
# --- stop-tunnel.sh ---
REMOTE_NET="192.168.3.0/24"
/sbin/ip route del $REMOTE_NET dev netb
/sbin/ip link set netb down
/sbin/ip tunnel del netb
exit 0
mount -t iso9660 /dev/cdrom /mnt/cdrom
# Mounts CD ROM. ISO 9660 is a standard CD ROM filesystem.
mount /mnt/cdrom
# Shortcut, if /mnt/cdrom listed in /etc/fstab
# As root...
mkdir /mnt/cdtest # Prepare a mount point, if not already there.
mount -r -t iso9660 -o loop cd-image.iso /mnt/cdtest # Mount the image.
# "-o loop" option equivalent to "losetup /dev/loop0"
cd /mnt/cdtest # Now, check the image.
ls -alR # List the files in the directory tree there.
# And so forth.
umount /mnt/cdrom
# You may now press the eject button and safely remove the disk.
SIZE=1000000 # 1 meg
head -c $SIZE < /dev/zero &gt; file # Set up file of designated size.
losetup /dev/loop0 file # Set it up as loopback device.
mke2fs /dev/loop0 # Create filesystem.
mount -o loop /dev/loop0 /mnt # Mount it.
# Thanks, S.C.
#!/bin/bash
# Adding a second hard drive to system.
# Software configuration. Assumes hardware already mounted.
# From an article by the author of the ABS Guide.
# In issue #38 of _Linux Gazette_, http://www.linuxgazette.com.
ROOT_UID=0 # This script must be run as root.
E_NOTROOT=67 # Non-root exit error.
if [ "$UID" -ne "$ROOT_UID" ]
then
echo "Must be root to run this script."
exit $E_NOTROOT
fi
# Use with extreme caution!
# If something goes wrong, you may wipe out your current filesystem.
NEWDISK=/dev/hdb # Assumes /dev/hdb vacant. Check!
MOUNTPOINT=/mnt/newdisk # Or choose another mount point.
fdisk $NEWDISK
mke2fs -cv $NEWDISK1 # Check for bad blocks (verbose output).
# Note: ^ /dev/hdb1, *not* /dev/hdb!
mkdir $MOUNTPOINT
chmod 777 $MOUNTPOINT # Makes new drive accessible to all users.
# Now, test ...
# mount -t ext2 /dev/hdb1 /mnt/newdisk
# Try creating a directory.
# If it works, umount it, and proceed.
# Final step:
# Add the following line to /etc/fstab.
# /dev/hdb1 /mnt/newdisk ext2 defaults 1 1
exit
lockfile /home/bozo/lockfiles/$0.lock
# Creates a write-protected lockfile prefixed with the name of the script.
lockfile /home/bozo/lockfiles/${0##*/}.lock
# A safer version of the above, as pointed out by E. Choroba.
appname=xyzip
# Application "xyzip" created lock file "/var/lock/xyzip.lock".
if [ -e "/var/lock/$appname.lock" ]
then #+ Prevent other programs & scripts
# from accessing files/resources used by xyzip.
...
flock $0 cat $0 &gt; lockfile__$0
# Set a lock on the script the above line appears in,
#+ while listing the script to stdout.
#!/bin/bash
# This script is for illustrative purposes only.
# Run it at your own peril -- it WILL freeze your system.
while true # Endless loop.
do
$0 & # This script invokes itself . . .
#+ forks an infinite number of times . . .
#+ until the system freezes up because all resources exhausted.
done # This is the notorious <span class="QUOTE">"sorcerer's appentice"</span> scenario.
exit 0 # Will not exit here, because this script will never terminate.
#!/bin/bash
# rot13a.sh: Same as "rot13.sh" script, but writes output to "secure" file.
# Usage: ./rot13a.sh filename
# or ./rot13a.sh <filename
# or ./rot13a.sh and supply keyboard input (stdin)
umask 177 # File creation mask.
# Files created by this script
#+ will have 600 permissions.
OUTFILE=decrypted.txt # Results output to file "decrypted.txt"
#+ which can only be read/written
# by invoker of script (or root).
cat "$@" | tr 'a-zA-Z' 'n-za-mN-ZA-M' &gt; $OUTFILE
# ^^ Input from stdin or a file. ^^^^^^^^^^ Output redirected to file.
exit 0
#! /usr/bin/env perl
print "This Perl script will run,\n";
print "even when I don't know where to find Perl.\n";
# Good for portable cross-platform scripts,
# where the Perl binaries may not be in the expected place.
# Thanks, S.C.
#!/bin/env bash
# Queries the $PATH enviromental variable for the location of bash.
# Therefore ...
# This script will run where Bash is not in its usual place, in /bin.
...
watch -n 5 tail /var/log/messages
# Shows tail end of system log, /var/log/messages, every five seconds.
#!/bin/bash
# backlight.sh
# reldate 02dec2011
# A bug in Fedora Core 16/17 messes up the keyboard backlight controls.
# This script is a quick-n-dirty workaround, essentially a shell wrapper
#+ for xrandr. It gives more control than on-screen sliders and widgets.
OUTPUT=$(xrandr | grep LV | awk '{print $1}') # Get display name!
INCR=.05 # For finer-grained control, set INCR to .03 or .02.
old_brightness=$(xrandr --verbose | grep rightness | awk '{ print $2 }')
if [ -z "$1" ]
then
bright=1 # If no command-line arg, set brightness to 1.0 (default).
else
if [ "$1" = "+" ]
then
bright=$(echo "scale=2; $old_brightness + $INCR" | bc) # +.05
else
if [ "$1" = "-" ]
then
bright=$(echo "scale=2; $old_brightness - $INCR" | bc) # -.05
else
if [ "$1" = "#" ] # Echoes current brightness; does not change it.
then
bright=$old_brightness
else
if [[ "$1" = "h" || "$1" = "H" ]]
then
echo
echo "Usage:"
echo "$0 [No args] Sets/resets brightness to default (1.0)."
echo "$0 + Increments brightness by 0.5."
echo "$0 - Decrements brightness by 0.5."
echo "$0 # Echoes current brightness without changing it."
echo "$0 N (number) Sets brightness to N (useful range .7 - 1.2)."
echo "$0 h [H] Echoes this help message."
echo "$0 any-other Gives xrandr usage message."
bright=$old_brightness
else
bright="$1"
fi
fi
fi
fi
fi
xrandr --output "$OUTPUT" --brightness "$bright" # See xrandr manpage.
# As root!
E_CHANGE0=$?
echo "Current brightness = $bright"
exit $E_CHANGE0
# =========== Or, alternately . . . ==================== #
#!/bin/bash
# backlight2.sh
# reldate 20jun2012
# A bug in Fedora Core 16/17 messes up the keyboard backlight controls.
# This is a quick-n-dirty workaround, an alternate to backlight.sh.
target_dir=\
/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0
# Hardware directory.
actual_brightness=$(cat $target_dir/actual_brightness)
max_brightness=$(cat $target_dir/max_brightness)
Brightness=$target_dir/brightness
let "req_brightness = actual_brightness" # Requested brightness.
if [ "$1" = "-" ]
then # Decrement brightness 1 notch.
let "req_brightness = $actual_brightness - 1"
else
if [ "$1" = "+" ]
then # Increment brightness 1 notch.
let "req_brightness = $actual_brightness + 1"
fi
fi
if [ $req_brightness -gt $max_brightness ]
then
req_brightness=$max_brightness
fi # Do not exceed max. hardware design brightness.
echo
echo "Old brightness = $actual_brightness"
echo "Max brightness = $max_brightness"
echo "Requested brightness = $req_brightness"
echo
# =====================================
echo $req_brightness &gt; $Brightness
# Must be root for this to take effect.
E_CHANGE1=$? # Successful?
# =====================================
if [ "$?" -eq 0 ]
then
echo "Changed brightness!"
else
echo "Failed to change brightness!"
fi
act_brightness=$(cat $Brightness)
echo "Actual brightness = $act_brightness"
scale0=2
sf=100 # Scale factor.
pct=$(echo "scale=$scale0; $act_brightness / $max_brightness * $sf" | bc)
echo "Percentage brightness = $pct%"
exit $E_CHANGE1
var1=value1 var2=value2 commandXXX
# $var1 and $var2 set in the environment of 'commandXXX' only.</pre>]
#!/bin/bash
# Copying a directory tree using cpio.
# Advantages of using 'cpio':
# Speed of copying. It's faster than 'tar' with pipes.
# Well suited for copying special files (named pipes, etc.)
#+ that 'cp' may choke on.
ARGS=2
E_BADARGS=65
if [ $# -ne "$ARGS" ]
then
echo "Usage: `basename $0` source destination"
exit $E_BADARGS
fi
source="$1"
destination="$2"
###################################################################
find "$source" -depth | cpio -admvp "$destination"
# ^^^^^ ^^^^^
# Read the 'find' and 'cpio' info pages to decipher these options.
# The above works only relative to $PWD (current directory) . . .
#+ full pathnames are specified.
###################################################################
# Exercise:
# --------
# Add code to check the exit status ($?) of the 'find | cpio' pipe
#+ and output appropriate error messages if anything went wrong.
exit $?
#!/bin/bash
# de-rpm.sh: Unpack an 'rpm' archive
: ${1?"Usage: `basename $0` target-file"}
# Must specify 'rpm' archive name as an argument.
TEMPFILE=$$.cpio # Tempfile with "unique" name.
# $$ is process ID of script.
rpm2cpio < $1 &gt; $TEMPFILE # Converts rpm archive into
#+ cpio archive.
cpio --make-directories -F $TEMPFILE -i # Unpacks cpio archive.
rm -f $TEMPFILE # Deletes cpio archive.
exit 0
# Exercise:
# Add check for whether 1) "target-file" exists and
#+ 2) it is an rpm archive.
# Hint: Parse output of 'file' command.
pax -wf daily_backup.pax ~/linux-server/files
# Creates a tar archive of all files in the target directory.
# Note that the options to pax must be in the correct order --
#+ pax -fw has an entirely different effect.
pax -f daily_backup.pax
# Lists the files in the archive.
pax -rf daily_backup.pax ~/bsd-server/files
# Restores the backed-up files from the Linux machine
#+ onto a BSD one.
# Find sh and Bash scripts in a given directory:
DIRECTORY=/usr/local/bin
KEYWORD=Bourne
# Bourne and Bourne-Again shell scripts
file $DIRECTORY/* | fgrep $KEYWORD
# Output:
# /usr/local/bin/burn-cd: Bourne-Again shell script text executable
# /usr/local/bin/burnit: Bourne-Again shell script text executable
# /usr/local/bin/cassette.sh: Bourne shell script text executable
# /usr/local/bin/copy-cd: Bourne-Again shell script text executable
# . . .
#!/bin/bash
# strip-comment.sh: Strips out the comments (/* COMMENT */) in a C program.
E_NOARGS=0
E_ARGERROR=66
E_WRONG_FILE_TYPE=67
if [ $# -eq "$E_NOARGS" ]
then
echo "Usage: `basename $0` C-program-file" &gt;&2 # Error message to stderr.
exit $E_ARGERROR
fi
# Test for correct file type.
type=`file $1 | awk '{ print $2, $3, $4, $5 }'`
# "file $1" echoes file type . . .
# Then awk removes the first field, the filename . . .
# Then the result is fed into the variable "type."
correct_type="ASCII C program text"
if [ "$type" != "$correct_type" ]
then
echo
echo "This script works on C program files only."
echo
exit $E_WRONG_FILE_TYPE
fi
# Rather cryptic sed script:
#--------
sed '
/^\/\*/d
/.*\*\//d
' $1
#--------
# Easy to understand if you take several hours to learn sed fundamentals.
# Need to add one more line to the sed script to deal with
#+ case where line of code has a comment following it on same line.
# This is left as a non-trivial exercise.
# Also, the above code deletes non-comment lines with a "*/" . . .
#+ not a desirable result.
exit 0
# ----------------------------------------------------------------
# Code below this line will not execute because of 'exit 0' above.
# Stephane Chazelas suggests the following alternative:
usage() {
echo "Usage: `basename $0` C-program-file" &gt;&2
exit 1
}
WEIRD=`echo -n -e '\377'` # or WEIRD=$'\377'
[[ $# -eq 1 ]] || usage
case `file "$1"` in
*"C program text"*) sed -e "s%/\*%${WEIRD}%g;s%\*/%${WEIRD}%g" "$1" \
| tr '\377\n' '\n\377' \
| sed -ne 'p;n' \
| tr -d '\n' | tr '\377' '\n';;
*) usage;;
esac
# This is still fooled by things like:
# printf("/*");
# or
# /* /* buggy embedded comment */
#
# To handle all special cases (comments in strings, comments in string
#+ where there is a \", \\" ...),
#+ the only way is to write a C parser (using lex or yacc perhaps?).
exit 0
#!/bin/bash
# What are all those mysterious binaries in /usr/X11R6/bin?
DIRECTORY="/usr/X11R6/bin"
# Try also "/bin", "/usr/bin", "/usr/local/bin", etc.
for file in $DIRECTORY/*
do
whatis `basename $file` # Echoes info about the binary.
done
exit 0
# Note: For this to work, you must create a "whatis" database
#+ with /usr/sbin/makewhatis.
# You may wish to redirect output of this script, like so:
# ./what.sh &gt;&gt;whatis.db
# or view it a page at a time on stdout,
# ./what.sh | less
#!/bin/bash
# wstrings.sh: "word-strings" (enhanced "strings" command)
#
# This script filters the output of "strings" by checking it
#+ against a standard word list file.
# This effectively eliminates gibberish and noise,
#+ and outputs only recognized words.
# ===========================================================
# Standard Check for Script Argument(s)
ARGS=1
E_BADARGS=85
E_NOFILE=86
if [ $# -ne $ARGS ]
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS
fi
if [ ! -f "$1" ] # Check if file exists.
then
echo "File \"$1\" does not exist."
exit $E_NOFILE
fi
# ===========================================================
MINSTRLEN=3 # Minimum string length.
WORDFILE=/usr/share/dict/linux.words # Dictionary file.
# May specify a different word list file
#+ of one-word-per-line format.
# For example, the "yawl" word-list package,
# http://bash.deta.in/yawl-0.3.2.tar.gz
wlist=`strings "$1" | tr A-Z a-z | tr '[:space:]' Z | \
tr -cs '[:alpha:]' Z | tr -s '\173-\377' Z | tr Z ' '`
# Translate output of 'strings' command with multiple passes of 'tr'.
# "tr A-Z a-z" converts to lowercase.
# "tr '[:space:]'" converts whitespace characters to Z's.
# "tr -cs '[:alpha:]' Z" converts non-alphabetic characters to Z's,
#+ and squeezes multiple consecutive Z's.
# "tr -s '\173-\377' Z" converts all characters past 'z' to Z's
#+ and squeezes multiple consecutive Z's,
#+ which gets rid of all the weird characters that the previous
#+ translation failed to deal with.
# Finally, "tr Z ' '" converts all those Z's to whitespace,
#+ which will be seen as word separators in the loop below.
# ***********************************************************************
# Note the technique of feeding/piping the output of 'tr' back to itself,
#+ but with different arguments and/or options on each successive pass.
# ***********************************************************************
for word in $wlist # Important:
# $wlist must not be quoted here.
# "$wlist" does not work.
# Why not?
do
strlen=${#word} # String length.
if [ "$strlen" -lt "$MINSTRLEN" ] # Skip over short strings.
then
continue
fi
grep -Fw $word "$WORDFILE" # Match whole words only.
# ^^^ # "Fixed strings" and
#+ "whole words" options.
done
exit $?
patch -p1 <patch-file
# Takes all the changes listed in 'patch-file'
# and applies them to the files referenced therein.
# This upgrades to a newer version of the package.
cd /usr/src
gzip -cd patchXX.gz | patch -p0
# Upgrading kernel source using 'patch'.
# From the Linux kernel docs "README",
# by anonymous author (Alan Cox?).
#!/bin/bash
# file-comparison.sh
ARGS=2 # Two args to script expected.
E_BADARGS=85
E_UNREADABLE=86
if [ $# -ne "$ARGS" ]
then
echo "Usage: `basename $0` file1 file2"
exit $E_BADARGS
fi
if [[ ! -r "$1" || ! -r "$2" ]]
then
echo "Both files to be compared must exist and be readable."
exit $E_UNREADABLE
fi
cmp $1 $2 &&gt; /dev/null
# Redirection to /dev/null buries the output of the "cmp" command.
# cmp -s $1 $2 has same result ("-s" silent flag to "cmp")
# Thank you Anders Gustavsson for pointing this out.
#
# Also works with 'diff', i.e.,
#+ diff $1 $2 &&gt; /dev/null
if [ $? -eq 0 ] # Test exit status of "cmp" command.
then
echo "File \"$1\" is identical to file \"$2\"."
else
echo "File \"$1\" differs from file \"$2\"."
fi
exit 0
echo "Usage: `basename $0` arg1 arg2 ... argn"
#!/bin/bash
address=/home/bozo/daily-journal.txt
echo "Basename of /home/bozo/daily-journal.txt = `basename $address`"
echo "Dirname of /home/bozo/daily-journal.txt = `dirname $address`"
echo
echo "My own home is `basename ~/`." # `basename ~` also works.
echo "The home of my home is `dirname ~/`." # `dirname ~` also works.
exit 0
#!/bin/bash
# splitcopy.sh
# A script that splits itself into chunks,
#+ then reassembles the chunks into an exact copy
#+ of the original script.
CHUNKSIZE=4 # Size of first chunk of split files.
OUTPREFIX=xx # csplit prefixes, by default,
#+ files with "xx" ...
csplit "$0" "$CHUNKSIZE"
# Some comment lines for padding . . .
# Line 15
# Line 16
# Line 17
# Line 18
# Line 19
# Line 20
cat "$OUTPREFIX"* &gt; "$0.copy" # Concatenate the chunks.
rm "$OUTPREFIX"* # Get rid of the chunks.
exit $?
#!/bin/bash
# file-integrity.sh: Checking whether files in a given directory
# have been tampered with.
E_DIR_NOMATCH=80
E_BAD_DBFILE=81
dbfile=File_record.md5
# Filename for storing records (database file).
set_up_database ()
{
echo ""$directory"" &gt; "$dbfile"
# Write directory name to first line of file.
md5sum "$directory"/* &gt;&gt; "$dbfile"
# Append md5 checksums and filenames.
}
check_database ()
{
local n=0
local filename
local checksum
# ------------------------------------------- #
# This file check should be unnecessary,
#+ but better safe than sorry.
if [ ! -r "$dbfile" ]
then
echo "Unable to read checksum database file!"
exit $E_BAD_DBFILE
fi
# ------------------------------------------- #
while read record[n]
do
directory_checked="${record[0]}"
if [ "$directory_checked" != "$directory" ]
then
echo "Directories do not match up!"
# Tried to use file for a different directory.
exit $E_DIR_NOMATCH
fi
if [ "$n" -gt 0 ] # Not directory name.
then
filename[n]=$( echo ${record[$n]} | awk '{ print $2 }' )
# md5sum writes records backwards,
#+ checksum first, then filename.
checksum[n]=$( md5sum "${filename[n]}" )
if [ "${record[n]}" = "${checksum[n]}" ]
then
echo "${filename[n]} unchanged."
elif [ "`basename ${filename[n]}`" != "$dbfile" ]
# Skip over checksum database file,
#+ as it will change with each invocation of script.
# ---
# This unfortunately means that when running
#+ this script on $PWD, tampering with the
#+ checksum database file will not be detected.
# Exercise: Fix this.
then
echo "${filename[n]} : CHECKSUM ERROR!"
# File has been changed since last checked.
fi
fi
let "n+=1"
done <"$dbfile" # Read from checksum database file.
}
# =================================================== #
# main ()
if [ -z "$1" ]
then
directory="$PWD" # If not specified,
else #+ use current working directory.
directory="$1"
fi
clear # Clear screen.
echo " Running file integrity check on $directory"
echo
# ------------------------------------------------------------------ #
if [ ! -r "$dbfile" ] # Need to create database file?
then
echo "Setting up database file, \""$directory"/"$dbfile"\"."; echo
set_up_database
fi
# ------------------------------------------------------------------ #
check_database # Do the actual work.
echo
# You may wish to redirect the stdout of this script to a file,
#+ especially if the directory checked has many files in it.
exit 0
# For a much more thorough file integrity check,
#+ consider the "Tripwire" package,
#+ http://sourceforge.net/projects/tripwire/.
#!/bin/bash
# Uudecodes all uuencoded files in current working directory.
lines=35 # Allow 35 lines for the header (very generous).
for File in * # Test all the files in $PWD.
do
search1=`head -n $lines $File | grep begin | wc -w`
search2=`tail -n $lines $File | grep end | wc -w`
# Uuencoded files have a "begin" near the beginning,
#+ and an "end" near the end.
if [ "$search1" -gt 0 ]
then
if [ "$search2" -gt 0 ]
then
echo "uudecoding - $File -"
uudecode $File
fi
fi
done
# Note that running this script upon itself fools it
#+ into thinking it is a uuencoded file,
#+ because it contains both "begin" and "end".
# Exercise:
# --------
# Modify this script to check each file for a newsgroup header,
#+ and skip to next if not found.
exit 0
# To encrypt a file:
openssl aes-128-ecb -salt -in file.txt -out file.encrypted \
-pass pass:my_password
# ^^^^^^^^^^^ User-selected password.
# aes-128-ecb is the encryption method chosen.
# To decrypt an openssl-encrypted file:
openssl aes-128-ecb -d -salt -in file.encrypted -out file.txt \
-pass pass:my_password
# ^^^^^^^^^^^ User-selected password.
# To encrypt a directory:
sourcedir="/home/bozo/testfiles"
encrfile="encr-dir.tar.gz"
password=my_secret_password
tar czvf - "$sourcedir" |
openssl des3 -salt -out "$encrfile" -pass pass:"$password"
# ^^^^ Uses des3 encryption.
# Writes encrypted file "encr-dir.tar.gz" in current working directory.
# To decrypt the resulting tarball:
openssl des3 -d -salt -in "$encrfile" -pass pass:"$password" |
tar -xzv
# Decrypts and unpacks into current working directory.
PREFIX=filename
tempfile=`mktemp $PREFIX.XXXXXX`
# ^^^^^^ Need at least 6 placeholders
#+ in the filename template.
# If no filename template supplied,
#+ "tmp.XXXXXXXXXX" is the default.
echo "tempfile name = $tempfile"
# tempfile name = filename.QA2ZpY
# or something similar...
# Creates a file of that name in the current working directory
#+ with 600 file permissions.
# A "umask 177" is therefore unnecessary,
#+ but it's good programming practice nevertheless.
ls /home/bozo | awk '{print "rm -rf " $1}' | more
# ^^^^
# Testing the effect of the following (disastrous) command-line:
# ls /home/bozo | awk '{print "rm -rf " $1}' | sh
# Hand off to the shell to execute . . . ^^</pre>]
#!/bin/bash
# ex40.sh (burn-cd.sh)
# Script to automate burning a CDR.
SPEED=10 # May use higher speed if your hardware supports it.
IMAGEFILE=cdimage.iso
CONTENTSFILE=contents
# DEVICE=/dev/cdrom For older versions of cdrecord
DEVICE="1,0,0"
DEFAULTDIR=/opt # This is the directory containing the data to be burned.
# Make sure it exists.
# Exercise: Add a test for this.
# Uses Joerg Schilling's "cdrecord" package:
# http://www.fokus.fhg.de/usr/schilling/cdrecord.html
# If this script invoked as an ordinary user, may need to suid cdrecord
#+ chmod u+s /usr/bin/cdrecord, as root.
# Of course, this creates a security hole, though a relatively minor one.
if [ -z "$1" ]
then
IMAGE_DIRECTORY=$DEFAULTDIR
# Default directory, if not specified on command-line.
else
IMAGE_DIRECTORY=$1
fi
# Create a "table of contents" file.
ls -lRF $IMAGE_DIRECTORY &gt; $IMAGE_DIRECTORY/$CONTENTSFILE
# The "l" option gives a "long" file listing.
# The "R" option makes the listing recursive.
# The "F" option marks the file types (directories get a trailing /).
echo "Creating table of contents."
# Create an image file preparatory to burning it onto the CDR.
mkisofs -r -o $IMAGEFILE $IMAGE_DIRECTORY
echo "Creating ISO9660 file system image ($IMAGEFILE)."
# Burn the CDR.
echo "Burning the disk."
echo "Please be patient, this will take a while."
wodim -v -isosize dev=$DEVICE $IMAGEFILE
# In newer Linux distros, the "wodim" utility assumes the
#+ functionality of "cdrecord."
exitcode=$?
echo "Exit code = $exitcode"
exit $exitcode
# Uses of 'cat'
cat filename # Lists the file.
cat file.1 file.2 file.3 &gt; file.123 # Combines three files into one.
cat filename | tr a-z A-Z
tr a-z A-Z < filename # Same effect, but starts one less process,
#+ and also dispenses with the pipe.
cp -u source_dir/* dest_dir
# "Synchronize" dest_dir to source_dir
#+ by copying over all newer and not previously existing files.
chmod +x filename
# Makes "filename" executable for all users.
chmod u+s filename
# Sets "suid" bit on "filename" permissions.
# An ordinary user may execute "filename" with same privileges as the file's owner.
# (This does not apply to shell scripts.)
chmod 644 filename
# Makes "filename" readable/writable to owner, readable to others
#+ (octal mode).
chmod 444 filename
# Makes "filename" read-only for all.
# Modifying the file (for example, with a text editor)
#+ not allowed for a user who does not own the file (except for root),
#+ and even the file owner must force a file-save
#+ if she modifies the file.
# Same restrictions apply for deleting the file.
chmod 1777 directory-name
# Gives everyone read, write, and execute permission in directory,
#+ however also sets the "sticky bit".
# This means that only the owner of the directory,
#+ owner of the file, and, of course, root
#+ can delete any particular file in that directory.
chmod 111 directory-name
# Gives everyone execute-only permission in a directory.
# This means that you can execute and READ the files in that directory
#+ (execute permission necessarily includes read permission
#+ because you can't execute a file without being able to read it).
# But you can't list the files or search for them with the "find" command.
# These restrictions do not apply to root.
chmod 000 directory-name
# No permissions at all for that directory.
# Can't read, write, or execute files in it.
# Can't even list files in it or "cd" to it.
# But, you can rename (mv) the directory
#+ or delete it (rmdir) if it is empty.
# You can even symlink to files in the directory,
#+ but you can't read, write, or execute the symlinks.
# These restrictions do not apply to root.
#!/bin/bash
# hello.sh: Saying "hello" or "goodbye"
#+ depending on how script is invoked.
# Make a link in current working directory ($PWD) to this script:
# ln -s hello.sh goodbye
# Now, try invoking this script both ways:
# ./hello.sh
# ./goodbye
HELLO_CALL=65
GOODBYE_CALL=66
if [ $0 = "./goodbye" ]
then
echo "Good-bye!"
# Some other goodbye-type commands, as appropriate.
exit $GOODBYE_CALL
fi
echo "Hello!"
# Some other hello-type commands, as appropriate.
exit $HELLO_CALL</pre>]
#!/bin/bash
# ex74.sh
# This is a buggy script.
# Where, oh where is the error?
a=37
if [$a -gt 27 ]
then
echo $a
fi
exit $? # 0! Why?
#!/bin/bash
# missing-keyword.sh
# What error message will this script generate? And why?
for a in 1 2 3
do
echo "$a"
# done # Required keyword 'done' commented out in line 8.
exit 0 # Will not exit here!
# === #
# From command line, after script terminates:
echo $? # 2
#!/bin/bash
# This script is supposed to delete all filenames in current directory
#+ containing embedded spaces.
# It doesn't work.
# Why not?
badname=`ls | grep ' '`
# Try this:
# echo "$badname"
rm "$badname"
exit 0
# Correct methods of deleting filenames containing spaces.
rm *\ *
rm *" "*
rm *' '*
# Thank you. S.C.
### debecho (debug-echo), by Stefano Falsetto ###
### Will echo passed parameters only if DEBUG is set to a value. ###
debecho () {
if [ ! -z "$DEBUG" ]; then
echo "$1" &gt;&2
# ^^^ to stderr
fi
}
DEBUG=on
Whatever=whatnot
debecho $Whatever # whatnot
DEBUG=
Whatever=notwhat
debecho $Whatever # (Will not echo.)
set -u # Or set -o nounset
# Setting a variable to null will not trigger the error/abort.
# unset_var=
echo $unset_var # Unset (and undeclared) variable.
echo "Should not echo!"
# sh t2.sh
# t2.sh: line 6: unset_var: unbound variable
#!/bin/bash
# assert.sh
#######################################################################
assert () # If condition false,
{ #+ exit from script
#+ with appropriate error message.
E_PARAM_ERR=98
E_ASSERT_FAILED=99
if [ -z "$2" ] # Not enough parameters passed
then #+ to assert() function.
return $E_PARAM_ERR # No damage done.
fi
lineno=$2
if [ ! $1 ]
then
echo "Assertion failed: \"$1\""
echo "File \"$0\", line $lineno" # Give name of file and line number.
exit $E_ASSERT_FAILED
# else
# return
# and continue executing the script.
fi
} # Insert a similar assert() function into a script you need to debug.
#######################################################################
a=5
b=4
condition="$a -lt $b" # Error message and exit from script.
# Try setting "condition" to something else
#+ and see what happens.
assert "$condition" $LINENO
# The remainder of the script executes only if the "assert" does not fail.
# Some commands.
# Some more commands . . .
echo "This statement echoes only if the \"assert\" does not fail."
# . . .
# More commands . . .
exit $?
trap '' 2
# Ignore interrupt 2 (Control-C), with no action specified.
trap 'echo "Control-C disabled."' 2
# Message when Control-C pressed.
#!/bin/bash
# Hunting variables with a trap.
trap 'echo Variable Listing --- a = $a b = $b' EXIT
# EXIT is the name of the signal generated upon exit from a script.
#
# The command specified by the "trap" doesn't execute until
#+ the appropriate signal is sent.
echo "This prints before the \"trap\" --"
echo "even though the script sees the \"trap\" first."
echo
a=39
b=36
exit 0
# Note that commenting out the 'exit' command makes no difference,
#+ since the script exits in any case after running out of commands.
#!/bin/bash
# logon.sh: A quick 'n dirty script to check whether you are on-line yet.
umask 177 # Make sure temp files are not world readable.
TRUE=1
LOGFILE=/var/log/messages
# Note that $LOGFILE must be readable
#+ (as root, chmod 644 /var/log/messages).
TEMPFILE=temp.$$
# Create a "unique" temp file name, using process id of the script.
# Using 'mktemp' is an alternative.
# For example:
# TEMPFILE=`mktemp temp.XXXXXX`
KEYWORD=address
# At logon, the line "remote IP address xxx.xxx.xxx.xxx"
# appended to /var/log/messages.
ONLINE=22
USER_INTERRUPT=13
CHECK_LINES=100
# How many lines in log file to check.
trap 'rm -f $TEMPFILE; exit $USER_INTERRUPT' TERM INT
# Cleans up the temp file if script interrupted by control-c.
echo
while [ $TRUE ] #Endless loop.
do
tail -n $CHECK_LINES $LOGFILE&gt; $TEMPFILE
# Saves last 100 lines of system log file as temp file.
# Necessary, since newer kernels generate many log messages at log on.
search=`grep $KEYWORD $TEMPFILE`
# Checks for presence of the "IP address" phrase,
#+ indicating a successful logon.
if [ ! -z "$search" ] # Quotes necessary because of possible spaces.
then
echo "On-line"
rm -f $TEMPFILE # Clean up temp file.
exit $ONLINE
else
echo -n "." # The -n option to echo suppresses newline,
#+ so you get continuous rows of dots.
fi
sleep 1
done
# Note: if you change the KEYWORD variable to "Exit",
#+ this script can be used while on-line
#+ to check for an unexpected logoff.
# Exercise: Change the script, per the above note,
# and prettify it.
exit 0
# Nick Drage suggests an alternate method:
while true
do ifconfig ppp0 | grep UP 1&gt; /dev/null && echo "connected" && exit 0
echo -n "." # Prints dots (.....) until connected.
sleep 2
done
# Problem: Hitting Control-C to terminate this process may be insufficient.
#+ (Dots may keep on echoing.)
# Exercise: Fix this.
# Stephane Chazelas has yet another alternative:
CHECK_INTERVAL=1
while ! tail -n 1 "$LOGFILE" | grep -q "$KEYWORD"
do echo -n .
sleep $CHECK_INTERVAL
done
echo "On-line"
# Exercise: Discuss the relative strengths and weaknesses
# of each of these various approaches.
#! /bin/bash
# progress-bar2.sh
# Author: Graham Ewart (with reformatting by ABS Guide author).
# Used in ABS Guide with permission (thanks!).
# Invoke this script with bash. It doesn't work with sh.
interval=1
long_interval=10
{
trap "exit" SIGUSR1
sleep $interval; sleep $interval
while true
do
echo -n '.' # Use dots.
sleep $interval
done; } & # Start a progress bar as a background process.
pid=$!
trap "echo !; kill -USR1 $pid; wait $pid" EXIT # To handle ^C.
echo -n 'Long-running process '
sleep $long_interval
echo ' Finished!'
kill -USR1 $pid
wait $pid # Stop the progress bar.
trap EXIT
exit $?
#!/bin/bash
trap 'echo "VARIABLE-TRACE&gt; \$variable = \"$variable\""' DEBUG
# Echoes the value of $variable after every command.
variable=29; line=$LINENO
echo " Just initialized \$variable to $variable in line number $line."
let "variable *= 3"; line=$LINENO
echo " Just multiplied \$variable by 3 in line number $line."
exit 0
# The "trap 'command1 . . . command2 . . .' DEBUG" construct is
#+ more appropriate in the context of a complex script,
#+ where inserting multiple "echo $variable" statements might be
#+ awkward and time-consuming.
# Thanks, Stephane Chazelas for the pointer.
Output of script:
VARIABLE-TRACE&gt; $variable = ""
VARIABLE-TRACE&gt; $variable = "29"
Just initialized $variable to 29.
VARIABLE-TRACE&gt; $variable = "29"
VARIABLE-TRACE&gt; $variable = "87"
Just multiplied $variable by 3.
VARIABLE-TRACE&gt; $variable = "87"
#!/bin/bash
# parent.sh
# Running multiple processes on an SMP box.
# Author: Tedman Eng
# This is the first of two scripts,
#+ both of which must be present in the current working directory.
LIMIT=$1 # Total number of process to start
NUMPROC=4 # Number of concurrent threads (forks?)
PROCID=1 # Starting Process ID
echo "My PID is $$"
function start_thread() {
if [ $PROCID -le $LIMIT ] ; then
./child.sh $PROCID&
let "PROCID++"
else
echo "Limit reached."
wait
exit
fi
}
while [ "$NUMPROC" -gt 0 ]; do
start_thread;
let "NUMPROC--"
done
while true
do
trap "start_thread" SIGRTMIN
done
exit 0
# ======== Second script follows ========
#!/bin/bash
# child.sh
# Running multiple processes on an SMP box.
# This script is called by parent.sh.
# Author: Tedman Eng
temp=$RANDOM
index=$1
shift
let "temp %= 5"
let "temp += 4"
echo "Starting $index Time:$temp" "$@"
sleep ${temp}
echo "Ending $index"
kill -s SIGRTMIN $PPID
exit 0
# ======================= SCRIPT AUTHOR'S NOTES ======================= #
# It's not completely bug free.
# I ran it with limit = 500 and after the first few hundred iterations,
#+ one of the concurrent threads disappeared!
# Not sure if this is collisions from trap signals or something else.
# Once the trap is received, there's a brief moment while executing the
#+ trap handler but before the next trap is set. During this time, it may
#+ be possible to miss a trap signal, thus miss spawning a child process.
# No doubt someone may spot the bug and will be writing
#+ . . . in the future.
# ===================================================================== #
# ----------------------------------------------------------------------#
#################################################################
# The following is the original script written by Vernia Damiano.
# Unfortunately, it doesn't work properly.
#################################################################
#!/bin/bash
# Must call script with at least one integer parameter
#+ (number of concurrent processes).
# All other parameters are passed through to the processes started.
INDICE=8 # Total number of process to start
TEMPO=5 # Maximum sleep time per process
E_BADARGS=65 # No arg(s) passed to script.
if [ $# -eq 0 ] # Check for at least one argument passed to script.
then
echo "Usage: `basename $0` number_of_processes [passed params]"
exit $E_BADARGS
fi
NUMPROC=$1 # Number of concurrent process
shift
PARAMETRI=( "$@" ) # Parameters of each process
function avvia() {
local temp
local index
temp=$RANDOM
index=$1
shift
let "temp %= $TEMPO"
let "temp += 1"
echo "Starting $index Time:$temp" "$@"
sleep ${temp}
echo "Ending $index"
kill -s SIGRTMIN $$
}
function parti() {
if [ $INDICE -gt 0 ] ; then
avvia $INDICE "${PARAMETRI[@]}" &
let "INDICE--"
else
trap : SIGRTMIN
fi
}
trap parti SIGRTMIN
while [ "$NUMPROC" -gt 0 ]; do
parti;
let "NUMPROC--"
done
wait
trap - SIGRTMIN
exit $?
: <<SCRIPT_AUTHOR_COMMENTS
I had the need to run a program, with specified options, on a number of
different files, using a SMP machine. So I thought [I'd] keep running
a specified number of processes and start a new one each time . . . one
of these terminates.
The "wait" instruction does not help, since it waits for a given process
or *all* process started in background. So I wrote [this] bash script
that can do the job, using the "trap" instruction.
--Vernia Damiano
SCRIPT_AUTHOR_COMMENTS
trap '' 2 # Signal 2 is Control-C, now disabled.
command
command
command
trap 2 # Reenables Control-C
</pre>]
#!/bin/bash
# logevents.sh
# Author: Stephane Chazelas.
# Used in ABS Guide with permission.
# Event logging to a file.
# Must be run as root (for write access in /var/log).
ROOT_UID=0 # Only users with $UID 0 have root privileges.
E_NOTROOT=67 # Non-root exit error.
if [ "$UID" -ne "$ROOT_UID" ]
then
echo "Must be root to run this script."
exit $E_NOTROOT
fi
FD_DEBUG1=3
FD_DEBUG2=4
FD_DEBUG3=5
# === Uncomment one of the two lines below to activate script. ===
# LOG_EVENTS=1
# LOG_VARS=1
log() # Writes time and date to log file.
{
echo "$(date) $*" &gt;&7 # This *appends* the date to the file.
# ^^^^^^^ command substitution
# See below.
}
case $LOG_LEVEL in
1) exec 3&gt;&2 4&gt; /dev/null 5&gt; /dev/null;;
2) exec 3&gt;&2 4&gt;&2 5&gt; /dev/null;;
3) exec 3&gt;&2 4&gt;&2 5&gt;&2;;
*) exec 3&gt; /dev/null 4&gt; /dev/null 5&gt; /dev/null;;
esac
FD_LOGVARS=6
if [[ $LOG_VARS ]]
then exec 6&gt;&gt; /var/log/vars.log
else exec 6&gt; /dev/null # Bury output.
fi
FD_LOGEVENTS=7
if [[ $LOG_EVENTS ]]
then
# exec 7 &gt;(exec gawk '{print strftime(), $0}' &gt;&gt; /var/log/event.log)
# Above line fails in versions of Bash more recent than 2.04. Why?
exec 7&gt;&gt; /var/log/event.log # Append to "event.log".
log # Write time and date.
else exec 7&gt; /dev/null # Bury output.
fi
echo "DEBUG3: beginning" &gt;&${FD_DEBUG3}
ls -l &gt;&5 2&gt;&4 # command1 &gt;&5 2&gt;&4
echo "Done" # command2
echo "sending mail" &gt;&${FD_LOGEVENTS}
# Writes "sending mail" to file descriptor #7.
exit 0</pre>]
#!/bin/bash
# ex30a.sh: "Colorized" version of ex30.sh.
# Crude address database
clear # Clear the screen.
echo -n " "
echo -e '\E[37;44m'"\033[1mContact List\033[0m"
# White on blue background
echo; echo
echo -e "\033[1mChoose one of the following persons:\033[0m"
# Bold
tput sgr0 # Reset attributes.
echo "(Enter only the first letter of name.)"
echo
echo -en '\E[47;34m'"\033[1mE\033[0m" # Blue
tput sgr0 # Reset colors to "normal."
echo "vans, Roland" # "[E]vans, Roland"
echo -en '\E[47;35m'"\033[1mJ\033[0m" # Magenta
tput sgr0
echo "ambalaya, Mildred"
echo -en '\E[47;32m'"\033[1mS\033[0m" # Green
tput sgr0
echo "mith, Julie"
echo -en '\E[47;31m'"\033[1mZ\033[0m" # Red
tput sgr0
echo "ane, Morris"
echo
read person
case "$person" in
# Note variable is quoted.
"E" | "e" )
# Accept upper or lowercase input.
echo
echo "Roland Evans"
echo "4321 Flash Dr."
echo "Hardscrabble, CO 80753"
echo "(303) 734-9874"
echo "(303) 734-9892 fax"
echo "revans@zzy.net"
echo "Business partner & old friend"
;;
"J" | "j" )
echo
echo "Mildred Jambalaya"
echo "249 E. 7th St., Apt. 19"
echo "New York, NY 10009"
echo "(212) 533-2814"
echo "(212) 533-9972 fax"
echo "milliej@loisaida.com"
echo "Girlfriend"
echo "Birthday: Feb. 11"
;;
# Add info for Smith & Zane later.
* )
# Default option.
# Empty input (hitting RETURN) fits here, too.
echo
echo "Not yet in database."
;;
esac
tput sgr0 # Reset colors to "normal."
echo
exit 0
#!/bin/bash
# Draw-box.sh: Drawing a box using ASCII characters.
# Script by Stefano Palmeri, with minor editing by document author.
# Minor edits suggested by Jim Angstadt.
# Used in the ABS Guide with permission.
######################################################################
### draw_box function doc ###
# The "draw_box" function lets the user
#+ draw a box in a terminal.
#
# Usage: draw_box ROW COLUMN HEIGHT WIDTH [COLOR]
# ROW and COLUMN represent the position
#+ of the upper left angle of the box you're going to draw.
# ROW and COLUMN must be greater than 0
#+ and less than current terminal dimension.
# HEIGHT is the number of rows of the box, and must be &gt; 0.
# HEIGHT + ROW must be <= than current terminal height.
# WIDTH is the number of columns of the box and must be &gt; 0.
# WIDTH + COLUMN must be <= than current terminal width.
#
# E.g.: If your terminal dimension is 20x80,
# draw_box 2 3 10 45 is good
# draw_box 2 3 19 45 has bad HEIGHT value (19+2 &gt; 20)
# draw_box 2 3 18 78 has bad WIDTH value (78+3 &gt; 80)
#
# COLOR is the color of the box frame.
# This is the 5th argument and is optional.
# 0=black 1=red 2=green 3=tan 4=blue 5=purple 6=cyan 7=white.
# If you pass the function bad arguments,
#+ it will just exit with code 65,
#+ and no messages will be printed on stderr.
#
# Clear the terminal before you start to draw a box.
# The clear command is not contained within the function.
# This allows the user to draw multiple boxes, even overlapping ones.
### end of draw_box function doc ###
######################################################################
draw_box(){
#=============#
HORZ="-"
VERT="|"
CORNER_CHAR="+"
MINARGS=4
E_BADARGS=65
#=============#
if [ $# -lt "$MINARGS" ]; then # If args are less than 4, exit.
exit $E_BADARGS
fi
# Looking for non digit chars in arguments.
# Probably it could be done better (exercise for the reader?).
if echo $@ | tr -d [:blank:] | tr -d [:digit:] | grep . &&gt; /dev/null; then
exit $E_BADARGS
fi
BOX_HEIGHT=`expr $3 - 1` # -1 correction needed because angle char "+"
BOX_WIDTH=`expr $4 - 1` #+ is a part of both box height and width.
T_ROWS=`tput lines` # Define current terminal dimension
T_COLS=`tput cols` #+ in rows and columns.
if [ $1 -lt 1 ] || [ $1 -gt $T_ROWS ]; then # Start checking if arguments
exit $E_BADARGS #+ are correct.
fi
if [ $2 -lt 1 ] || [ $2 -gt $T_COLS ]; then
exit $E_BADARGS
fi
if [ `expr $1 + $BOX_HEIGHT + 1` -gt $T_ROWS ]; then
exit $E_BADARGS
fi
if [ `expr $2 + $BOX_WIDTH + 1` -gt $T_COLS ]; then
exit $E_BADARGS
fi
if [ $3 -lt 1 ] || [ $4 -lt 1 ]; then
exit $E_BADARGS
fi # End checking arguments.
plot_char(){ # Function within a function.
echo -e "\E[${1};${2}H"$3
}
echo -ne "\E[3${5}m" # Set box frame color, if defined.
# start drawing the box
count=1 # Draw vertical lines using
for (( r=$1; count<=$BOX_HEIGHT; r++)); do #+ plot_char function.
plot_char $r $2 $VERT
let count=count+1
done
count=1
c=`expr $2 + $BOX_WIDTH`
for (( r=$1; count<=$BOX_HEIGHT; r++)); do
plot_char $r $c $VERT
let count=count+1
done
count=1 # Draw horizontal lines using
for (( c=$2; count<=$BOX_WIDTH; c++)); do #+ plot_char function.
plot_char $1 $c $HORZ
let count=count+1
done
count=1
r=`expr $1 + $BOX_HEIGHT`
for (( c=$2; count<=$BOX_WIDTH; c++)); do
plot_char $r $c $HORZ
let count=count+1
done
plot_char $1 $2 $CORNER_CHAR # Draw box angles.
plot_char $1 `expr $2 + $BOX_WIDTH` $CORNER_CHAR
plot_char `expr $1 + $BOX_HEIGHT` $2 $CORNER_CHAR
plot_char `expr $1 + $BOX_HEIGHT` `expr $2 + $BOX_WIDTH` $CORNER_CHAR
echo -ne "\E[0m" # Restore old colors.
P_ROWS=`expr $T_ROWS - 1` # Put the prompt at bottom of the terminal.
echo -e "\E[${P_ROWS};1H"
}
# Now, let's try drawing a box.
clear # Clear the terminal.
R=2 # Row
C=3 # Column
H=10 # Height
W=45 # Width
col=1 # Color (red)
draw_box $R $C $H $W $col # Draw the box.
exit 0
# Exercise:
# --------
# Add the option of printing text within the drawn box.
#!/bin/bash
# color-echo.sh: Echoing text messages in color.
# Modify this script for your own purposes.
# It's easier than hand-coding color.
black='\E[30;47m'
red='\E[31;47m'
green='\E[32;47m'
yellow='\E[33;47m'
blue='\E[34;47m'
magenta='\E[35;47m'
cyan='\E[36;47m'
white='\E[37;47m'
alias Reset="tput sgr0" # Reset text attributes to normal
#+ without clearing screen.
cecho () # Color-echo.
# Argument $1 = message
# Argument $2 = color
{
local default_msg="No message passed."
# Doesn't really need to be a local variable.
message=${1:-$default_msg} # Defaults to default message.
color=${2:-$black} # Defaults to black, if not specified.
echo -e "$color"
echo "$message"
Reset # Reset to normal.
return
}
# Now, let's try it out.
# ----------------------------------------------------
cecho "Feeling blue..." $blue
cecho "Magenta looks more like purple." $magenta
cecho "Green with envy." $green
cecho "Seeing red?" $red
cecho "Cyan, more familiarly known as aqua." $cyan
cecho "No color passed (defaults to black)."
# Missing $color argument.
cecho "\"Empty\" color passed (defaults to black)." ""
# Empty $color argument.
cecho
# Missing $message and $color arguments.
cecho "" ""
# Empty $message and $color arguments.
# ----------------------------------------------------
echo
exit 0
# Exercises:
# ---------
# 1) Add the "bold" attribute to the 'cecho ()' function.
# 2) Add options for colored backgrounds.
#!/bin/bash
# horserace.sh: Very simple horserace simulation.
# Author: Stefano Palmeri
# Used with permission.
################################################################
# Goals of the script:
# playing with escape sequences and terminal colors.
#
# Exercise:
# Edit the script to make it run less randomly,
#+ set up a fake betting shop . . .
# Um . . . um . . . it's starting to remind me of a movie . . .
#
# The script gives each horse a random handicap.
# The odds are calculated upon horse handicap
#+ and are expressed in European(?) style.
# E.g., odds=3.75 means that if you bet $1 and win,
#+ you receive $3.75.
#
# The script has been tested with a GNU/Linux OS,
#+ using xterm and rxvt, and konsole.
# On a machine with an AMD 900 MHz processor,
#+ the average race time is 75 seconds.
# On faster computers the race time would be lower.
# So, if you want more suspense, reset the USLEEP_ARG variable.
#
# Script by Stefano Palmeri.
################################################################
E_RUNERR=65
# Check if md5sum and bc are installed.
if ! which bc &&gt; /dev/null; then
echo bc is not installed.
echo "Can\'t run . . . "
exit $E_RUNERR
fi
if ! which md5sum &&gt; /dev/null; then
echo md5sum is not installed.
echo "Can\'t run . . . "
exit $E_RUNERR
fi
# Set the following variable to slow down script execution.
# It will be passed as the argument for usleep (man usleep)
#+ and is expressed in microseconds (500000 = half a second).
USLEEP_ARG=0
# Clean up the temp directory, restore terminal cursor and
#+ terminal colors -- if script interrupted by Ctl-C.
trap 'echo -en "\E[?25h"; echo -en "\E[0m"; stty echo;\
tput cup 20 0; rm -fr $HORSE_RACE_TMP_DIR' TERM EXIT
# See the chapter on debugging for an explanation of 'trap.'
# Set a unique (paranoid) name for the temp directory the script needs.
HORSE_RACE_TMP_DIR=$HOME/.horserace-`date +%s`-`head -c10 /dev/urandom \
| md5sum | head -c30`
# Create the temp directory and move right in.
mkdir $HORSE_RACE_TMP_DIR
cd $HORSE_RACE_TMP_DIR
# This function moves the cursor to line $1 column $2 and then prints $3.
# E.g.: "move_and_echo 5 10 linux" is equivalent to
#+ "tput cup 4 9; echo linux", but with one command instead of two.
# Note: "tput cup" defines 0 0 the upper left angle of the terminal,
#+ echo defines 1 1 the upper left angle of the terminal.
move_and_echo() {
echo -ne "\E[${1};${2}H""$3"
}
# Function to generate a pseudo-random number between 1 and 9.
random_1_9 ()
{
head -c10 /dev/urandom | md5sum | tr -d [a-z] | tr -d 0 | cut -c1
}
# Two functions that simulate "movement," when drawing the horses.
draw_horse_one() {
echo -n " "//$MOVE_HORSE//
}
draw_horse_two(){
echo -n " "\\\\$MOVE_HORSE\\\\
}
# Define current terminal dimension.
N_COLS=`tput cols`
N_LINES=`tput lines`
# Need at least a 20-LINES X 80-COLUMNS terminal. Check it.
if [ $N_COLS -lt 80 ] || [ $N_LINES -lt 20 ]; then
echo "`basename $0` needs a 80-cols X 20-lines terminal."
echo "Your terminal is ${N_COLS}-cols X ${N_LINES}-lines."
exit $E_RUNERR
fi
# Start drawing the race field.
# Need a string of 80 chars. See below.
BLANK80=`seq -s "" 100 | head -c80`
clear
# Set foreground and background colors to white.
echo -ne '\E[37;47m'
# Move the cursor on the upper left angle of the terminal.
tput cup 0 0
# Draw six white lines.
for n in `seq 5`; do
echo $BLANK80 # Use the 80 chars string to colorize the terminal.
done
# Sets foreground color to black.
echo -ne '\E[30m'
move_and_echo 3 1 "START 1"
move_and_echo 3 75 FINISH
move_and_echo 1 5 "|"
move_and_echo 1 80 "|"
move_and_echo 2 5 "|"
move_and_echo 2 80 "|"
move_and_echo 4 5 "| 2"
move_and_echo 4 80 "|"
move_and_echo 5 5 "V 3"
move_and_echo 5 80 "V"
# Set foreground color to red.
echo -ne '\E[31m'
# Some ASCII art.
move_and_echo 1 8 "..@@@..@@@@@...@@@@@.@...@..@@@@..."
move_and_echo 2 8 ".@...@...@.......@...@...@.@......."
move_and_echo 3 8 ".@@@@@...@.......@...@@@@@.@@@@...."
move_and_echo 4 8 ".@...@...@.......@...@...@.@......."
move_and_echo 5 8 ".@...@...@.......@...@...@..@@@@..."
move_and_echo 1 43 "@@@@...@@@...@@@@..@@@@..@@@@."
move_and_echo 2 43 "@...@.@...@.@.....@.....@....."
move_and_echo 3 43 "@@@@..@@@@@.@.....@@@@...@@@.."
move_and_echo 4 43 "@..@..@...@.@.....@.........@."
move_and_echo 5 43 "@...@.@...@..@@@@..@@@@.@@@@.."
# Set foreground and background colors to green.
echo -ne '\E[32;42m'
# Draw eleven green lines.
tput cup 5 0
for n in `seq 11`; do
echo $BLANK80
done
# Set foreground color to black.
echo -ne '\E[30m'
tput cup 5 0
# Draw the fences.
echo "++++++++++++++++++++++++++++++++++++++\
++++++++++++++++++++++++++++++++++++++++++"
tput cup 15 0
echo "++++++++++++++++++++++++++++++++++++++\
++++++++++++++++++++++++++++++++++++++++++"
# Set foreground and background colors to white.
echo -ne '\E[37;47m'
# Draw three white lines.
for n in `seq 3`; do
echo $BLANK80
done
# Set foreground color to black.
echo -ne '\E[30m'
# Create 9 files to stores handicaps.
for n in `seq 10 7 68`; do
touch $n
done
# Set the first type of "horse" the script will draw.
HORSE_TYPE=2
# Create position-file and odds-file for every "horse".
#+ In these files, store the current position of the horse,
#+ the type and the odds.
for HN in `seq 9`; do
touch horse_${HN}_position
touch odds_${HN}
echo \-1 &gt; horse_${HN}_position
echo $HORSE_TYPE &gt;&gt; horse_${HN}_position
# Define a random handicap for horse.
HANDICAP=`random_1_9`
# Check if the random_1_9 function returned a good value.
while ! echo $HANDICAP | grep [1-9] &&gt; /dev/null; do
HANDICAP=`random_1_9`
done
# Define last handicap position for horse.
LHP=`expr $HANDICAP \* 7 + 3`
for FILE in `seq 10 7 $LHP`; do
echo $HN &gt;&gt; $FILE
done
# Calculate odds.
case $HANDICAP in
1) ODDS=`echo $HANDICAP \* 0.25 + 1.25 | bc`
echo $ODDS &gt; odds_${HN}
;;
2 | 3) ODDS=`echo $HANDICAP \* 0.40 + 1.25 | bc`
echo $ODDS &gt; odds_${HN}
;;
4 | 5 | 6) ODDS=`echo $HANDICAP \* 0.55 + 1.25 | bc`
echo $ODDS &gt; odds_${HN}
;;
7 | 8) ODDS=`echo $HANDICAP \* 0.75 + 1.25 | bc`
echo $ODDS &gt; odds_${HN}
;;
9) ODDS=`echo $HANDICAP \* 0.90 + 1.25 | bc`
echo $ODDS &gt; odds_${HN}
esac
done
# Print odds.
print_odds() {
tput cup 6 0
echo -ne '\E[30;42m'
for HN in `seq 9`; do
echo "#$HN odds-&gt;" `cat odds_${HN}`
done
}
# Draw the horses at starting line.
draw_horses() {
tput cup 6 0
echo -ne '\E[30;42m'
for HN in `seq 9`; do
echo /\\$HN/\\" "
done
}
print_odds
echo -ne '\E[47m'
# Wait for a enter key press to start the race.
# The escape sequence '\E[?25l' disables the cursor.
tput cup 17 0
echo -e '\E[?25l'Press [enter] key to start the race...
read -s
# Disable normal echoing in the terminal.
# This avoids key presses that might "contaminate" the screen
#+ during the race.
stty -echo
# --------------------------------------------------------
# Start the race.
draw_horses
echo -ne '\E[37;47m'
move_and_echo 18 1 $BLANK80
echo -ne '\E[30m'
move_and_echo 18 1 Starting...
sleep 1
# Set the column of the finish line.
WINNING_POS=74
# Define the time the race started.
START_TIME=`date +%s`
# COL variable needed by following "while" construct.
COL=0
while [ $COL -lt $WINNING_POS ]; do
MOVE_HORSE=0
# Check if the random_1_9 function has returned a good value.
while ! echo $MOVE_HORSE | grep [1-9] &&gt; /dev/null; do
MOVE_HORSE=`random_1_9`
done
# Define old type and position of the "randomized horse".
HORSE_TYPE=`cat horse_${MOVE_HORSE}_position | tail -n 1`
COL=$(expr `cat horse_${MOVE_HORSE}_position | head -n 1`)
ADD_POS=1
# Check if the current position is an handicap position.
if seq 10 7 68 | grep -w $COL &&gt; /dev/null; then
if grep -w $MOVE_HORSE $COL &&gt; /dev/null; then
ADD_POS=0
grep -v -w $MOVE_HORSE $COL &gt; ${COL}_new
rm -f $COL
mv -f ${COL}_new $COL
else ADD_POS=1
fi
else ADD_POS=1
fi
COL=`expr $COL + $ADD_POS`
echo $COL &gt; horse_${MOVE_HORSE}_position # Store new position.
# Choose the type of horse to draw.
case $HORSE_TYPE in
1) HORSE_TYPE=2; DRAW_HORSE=draw_horse_two
;;
2) HORSE_TYPE=1; DRAW_HORSE=draw_horse_one
esac
echo $HORSE_TYPE &gt;&gt; horse_${MOVE_HORSE}_position
# Store current type.
# Set foreground color to black and background to green.
echo -ne '\E[30;42m'
# Move the cursor to new horse position.
tput cup `expr $MOVE_HORSE + 5` \
`cat horse_${MOVE_HORSE}_position | head -n 1`
# Draw the horse.
$DRAW_HORSE
usleep $USLEEP_ARG
# When all horses have gone beyond field line 15, reprint odds.
touch fieldline15
if [ $COL = 15 ]; then
echo $MOVE_HORSE &gt;&gt; fieldline15
fi
if [ `wc -l fieldline15 | cut -f1 -d " "` = 9 ]; then
print_odds
: &gt; fieldline15
fi
# Define the leading horse.
HIGHEST_POS=`cat *position | sort -n | tail -1`
# Set background color to white.
echo -ne '\E[47m'
tput cup 17 0
echo -n Current leader: `grep -w $HIGHEST_POS *position | cut -c7`\
" "
done
# Define the time the race finished.
FINISH_TIME=`date +%s`
# Set background color to green and enable blinking text.
echo -ne '\E[30;42m'
echo -en '\E[5m'
# Make the winning horse blink.
tput cup `expr $MOVE_HORSE + 5` \
`cat horse_${MOVE_HORSE}_position | head -n 1`
$DRAW_HORSE
# Disable blinking text.
echo -en '\E[25m'
# Set foreground and background color to white.
echo -ne '\E[37;47m'
move_and_echo 18 1 $BLANK80
# Set foreground color to black.
echo -ne '\E[30m'
# Make winner blink.
tput cup 17 0
echo -e "\E[5mWINNER: $MOVE_HORSE\E[25m"" Odds: `cat odds_${MOVE_HORSE}`"\
" Race time: `expr $FINISH_TIME - $START_TIME` secs"
# Restore cursor and old colors.
echo -en "\E[?25h"
echo -en "\E[0m"
# Restore echoing.
stty echo
# Remove race temp directory.
rm -rf $HORSE_RACE_TMP_DIR
tput cup 19 0
exit 0</pre>]
#!/bin/bash
# int-or-string.sh
a=2334 # Integer.
let "a += 1"
echo "a = $a " # a = 2335
echo # Integer, still.
b=${a/23/BB} # Substitute "BB" for "23".
# This transforms $b into a string.
echo "b = $b" # b = BB35
declare -i b # Declaring it an integer doesn't help.
echo "b = $b" # b = BB35
let "b += 1" # BB35 + 1
echo "b = $b" # b = 1
echo # Bash sets the "integer value" of a string to 0.
c=BB34
echo "c = $c" # c = BB34
d=${c/BB/23} # Substitute "23" for "BB".
# This makes $d an integer.
echo "d = $d" # d = 2334
let "d += 1" # 2334 + 1
echo "d = $d" # d = 2335
echo
# What about null variables?
e='' # ... Or e="" ... Or e=
echo "e = $e" # e =
let "e += 1" # Arithmetic operations allowed on a null variable?
echo "e = $e" # e = 1
echo # Null variable transformed into an integer.
# What about undeclared variables?
echo "f = $f" # f =
let "f += 1" # Arithmetic operations allowed?
echo "f = $f" # f = 1
echo # Undeclared variable transformed into an integer.
#
# However ...
let "f /= $undecl_var" # Divide by zero?
# let: f /= : syntax error: operand expected (error token is " ")
# Syntax error! Variable $undecl_var is not set to zero here!
#
# But still ...
let "f /= 0"
# let: f /= 0: division by 0 (error token is "0")
# Expected behavior.
# Bash (usually) sets the "integer value" of null to zero
#+ when performing an arithmetic operation.
# But, don't try this at home, folks!
# It's undocumented and probably non-portable behavior.
# Conclusion: Variables in Bash are untyped,
#+ with all attendant consequences.
exit $?</pre>]
a=8
# All of the comparisons below are equivalent.
test "$a" -lt 16 && echo "yes, $a < 16" # "and list"
/bin/test "$a" -lt 16 && echo "yes, $a < 16"
[ "$a" -lt 16 ] && echo "yes, $a < 16"
[[ $a -lt 16 ]] && echo "yes, $a < 16" # Quoting variables within
(( a < 16 )) && echo "yes, $a < 16" # [[ ]] and (( )) not necessary.
city="New York"
# Again, all of the comparisons below are equivalent.
test "$city" \< Paris && echo "Yes, Paris is greater than $city"
# Greater ASCII order.
/bin/test "$city" \< Paris && echo "Yes, Paris is greater than $city"
[ "$city" \< Paris ] && echo "Yes, Paris is greater than $city"
[[ $city < Paris ]] && echo "Yes, Paris is greater than $city"
# Need not quote $city.
# Thank you, S.C.</pre>]
[[ $a == z* ]] # True if $a starts with an "z" (pattern matching).
[[ $a == "z*" ]] # True if $a is equal to z* (literal matching).
[ $a == z* ] # File globbing and word splitting take place.
[ "$a" == "z*" ] # True if $a is equal to z* (literal matching).
# Thanks, Stéphane Chazelas
String='' # Zero-length ("null") string variable.
if [ -z "$String" ]
then
echo "\$String is null."
else
echo "\$String is NOT null."
fi # $String is null.
#!/bin/bash
a=4
b=5
# Here "a" and "b" can be treated either as integers or strings.
# There is some blurring between the arithmetic and string comparisons,
#+ since Bash variables are not strongly typed.
# Bash permits integer operations and comparisons on variables
#+ whose value consists of all-integer characters.
# Caution advised, however.
echo
if [ "$a" -ne "$b" ]
then
echo "$a is not equal to $b"
echo "(arithmetic comparison)"
fi
echo
if [ "$a" != "$b" ]
then
echo "$a is not equal to $b."
echo "(string comparison)"
# "4" != "5"
# ASCII 52 != ASCII 53
fi
# In this particular instance, both "-ne" and "!=" work.
echo
exit 0
#!/bin/bash
# str-test.sh: Testing null strings and unquoted strings,
#+ but not strings and sealing wax, not to mention cabbages and kings . . .
# Using if [ ... ]
# If a string has not been initialized, it has no defined value.
# This state is called "null" (not the same as zero!).
if [ -n $string1 ] # string1 has not been declared or initialized.
then
echo "String \"string1\" is not null."
else
echo "String \"string1\" is null."
fi # Wrong result.
# Shows $string1 as not null, although it was not initialized.
echo
# Let's try it again.
if [ -n "$string1" ] # This time, $string1 is quoted.
then
echo "String \"string1\" is not null."
else
echo "String \"string1\" is null."
fi # Quote strings within test brackets!
echo
if [ $string1 ] # This time, $string1 stands naked.
then
echo "String \"string1\" is not null."
else
echo "String \"string1\" is null."
fi # This works fine.
# The [ ... ] test operator alone detects whether the string is null.
# However it is good practice to quote it (if [ "$string1" ]).
#
# As Stephane Chazelas points out,
# if [ $string1 ] has one argument, "]"
# if [ "$string1" ] has two arguments, the empty "$string1" and "]"
echo
string1=initialized
if [ $string1 ] # Again, $string1 stands unquoted.
then
echo "String \"string1\" is not null."
else
echo "String \"string1\" is null."
fi # Again, gives correct result.
# Still, it is better to quote it ("$string1"), because . . .
string1="a = b"
if [ $string1 ] # Again, $string1 stands unquoted.
then
echo "String \"string1\" is not null."
else
echo "String \"string1\" is null."
fi # Not quoting "$string1" now gives wrong result!
exit 0 # Thank you, also, Florian Wisser, for the "heads-up".
#!/bin/bash
# zmore
# View gzipped files with 'more' filter.
E_NOARGS=85
E_NOTFOUND=86
E_NOTGZIP=87
if [ $# -eq 0 ] # same effect as: if [ -z "$1" ]
# $1 can exist, but be empty: zmore "" arg2 arg3
then
echo "Usage: `basename $0` filename" &gt;&2
# Error message to stderr.
exit $E_NOARGS
# Returns 85 as exit status of script (error code).
fi
filename=$1
if [ ! -f "$filename" ] # Quoting $filename allows for possible spaces.
then
echo "File $filename not found!" &gt;&2 # Error message to stderr.
exit $E_NOTFOUND
fi
if [ ${filename##*.} != "gz" ]
# Using bracket in variable substitution.
then
echo "File $1 is not a gzipped file!"
exit $E_NOTGZIP
fi
zcat $1 | more
# Uses the 'more' filter.
# May substitute 'less' if desired.
exit $? # Script returns exit status of pipe.
# Actually "exit $?" is unnecessary, as the script will, in any case,
#+ return the exit status of the last command executed.
[[ condition1 && condition2 ]]
if [ "$expr1" -a "$expr2" ]
then
echo "Both expr1 and expr2 are true."
else
echo "Either expr1 or expr2 is false."
fi
[ 1 -eq 1 ] && [ -n "`echo true 1&gt;&2`" ] # true
[ 1 -eq 2 ] && [ -n "`echo true 1&gt;&2`" ] # (no output)
# ^^^^^^^ False condition. So far, everything as expected.
# However ...
[ 1 -eq 2 -a -n "`echo true 1&gt;&2`" ] # true
# ^^^^^^^ False condition. So, why "true" output?
# Is it because both condition clauses within brackets evaluate?
[[ 1 -eq 2 && -n "`echo true 1&gt;&2`" ]] # (no output)
# No, that's not it.
# Apparently && and || "short-circuit" while -a and -o do not.</pre>]
[]
#!/bin/bash
# spam-lookup.sh: Look up abuse contact to report a spammer.
# Thanks, Michael Zick.
# Check for command-line arg.
ARGCOUNT=1
E_WRONGARGS=85
if [ $# -ne "$ARGCOUNT" ]
then
echo "Usage: `basename $0` domain-name"
exit $E_WRONGARGS
fi
dig +short $1.contacts.abuse.net -c in -t txt
# Also try:
# dig +nssearch $1
# Tries to find "authoritative name servers" and display SOA records.
# The following also works:
# whois -h whois.abuse.net $1
# ^^ ^^^^^^^^^^^^^^^ Specify host.
# Can even lookup multiple spammers with this, i.e."
# whois -h whois.abuse.net $spamdomain1 $spamdomain2 . . .
# Exercise:
# --------
# Expand the functionality of this script
#+ so that it automatically e-mails a notification
#+ to the responsible ISP's contact address(es).
# Hint: use the "mail" command.
exit $?
# spam-lookup.sh chinatietong.com
# A known spam domain.
# "crnet_mgr@chinatietong.com"
# "crnet_tec@chinatietong.com"
# "postmaster@chinatietong.com"
# For a more elaborate version of this script,
#+ see the SpamViz home page, http://www.spamviz.net/index.html.
#! /bin/bash
# is-spammer.sh: Identifying spam domains
# $Id: is-spammer, v 1.4 2004/09/01 19:37:52 mszick Exp $
# Above line is RCS ID info.
#
# This is a simplified version of the "is_spammer.bash
#+ script in the Contributed Scripts appendix.
# is-spammer <domain.name&gt;
# Uses an external program: 'dig'
# Tested with version: 9.2.4rc5
# Uses functions.
# Uses IFS to parse strings by assignment into arrays.
# And even does something useful: checks e-mail blacklists.
# Use the domain.name(s) from the text body:
# http://www.good_stuff.spammer.biz/just_ignore_everything_else
# ^^^^^^^^^^^
# Or the domain.name(s) from any e-mail address:
# Really_Good_Offer@spammer.biz
#
# as the only argument to this script.
#(PS: have your Inet connection running)
#
# So, to invoke this script in the above two instances:
# is-spammer.sh spammer.biz
# Whitespace == :Space:Tab:Line Feed:Carriage Return:
WSP_IFS=$'\x20'$'\x09'$'\x0A'$'\x0D'
# No Whitespace == Line Feed:Carriage Return
No_WSP=$'\x0A'$'\x0D'
# Field separator for dotted decimal ip addresses
ADR_IFS=${No_WSP}'.'
# Get the dns text resource record.
# get_txt <error_code&gt; <list_query&gt;
get_txt() {
# Parse $1 by assignment at the dots.
local -a dns
IFS=$ADR_IFS
dns=( $1 )
IFS=$WSP_IFS
if [ "${dns[0]}" == '127' ]
then
# See if there is a reason.
echo $(dig +short $2 -t txt)
fi
}
# Get the dns address resource record.
# chk_adr <rev_dns&gt; <list_server&gt;
chk_adr() {
local reply
local server
local reason
server=${1}${2}
reply=$( dig +short ${server} )
# If reply might be an error code . . .
if [ ${#reply} -gt 6 ]
then
reason=$(get_txt ${reply} ${server} )
reason=${reason:-${reply}}
fi
echo ${reason:-' not blacklisted.'}
}
# Need to get the IP address from the name.
echo 'Get address of: '$1
ip_adr=$(dig +short $1)
dns_reply=${ip_adr:-' no answer '}
echo ' Found address: '${dns_reply}
# A valid reply is at least 4 digits plus 3 dots.
if [ ${#ip_adr} -gt 6 ]
then
echo
declare query
# Parse by assignment at the dots.
declare -a dns
IFS=$ADR_IFS
dns=( ${ip_adr} )
IFS=$WSP_IFS
# Reorder octets into dns query order.
rev_dns="${dns[3]}"'.'"${dns[2]}"'.'"${dns[1]}"'.'"${dns[0]}"'.'
# See: http://www.spamhaus.org (Conservative, well maintained)
echo -n 'spamhaus.org says: '
echo $(chk_adr ${rev_dns} 'sbl-xbl.spamhaus.org')
# See: http://ordb.org (Open mail relays)
echo -n ' ordb.org says: '
echo $(chk_adr ${rev_dns} 'relays.ordb.org')
# See: http://www.spamcop.net/ (You can report spammers here)
echo -n ' spamcop.net says: '
echo $(chk_adr ${rev_dns} 'bl.spamcop.net')
# # # other blacklist operations # # #
# See: http://cbl.abuseat.org.
echo -n ' abuseat.org says: '
echo $(chk_adr ${rev_dns} 'cbl.abuseat.org')
# See: http://dsbl.org/usage (Various mail relays)
echo
echo 'Distributed Server Listings'
echo -n ' list.dsbl.org says: '
echo $(chk_adr ${rev_dns} 'list.dsbl.org')
echo -n ' multihop.dsbl.org says: '
echo $(chk_adr ${rev_dns} 'multihop.dsbl.org')
echo -n 'unconfirmed.dsbl.org says: '
echo $(chk_adr ${rev_dns} 'unconfirmed.dsbl.org')
else
echo
echo 'Could not use that address.'
fi
exit 0
# Exercises:
# --------
# 1) Check arguments to script,
# and exit with appropriate error message if necessary.
# 2) Check if on-line at invocation of script,
# and exit with appropriate error message if necessary.
# 3) Substitute generic variables for "hard-coded" BHL domains.
# 4) Set a time-out for the script using the "+time=" option
to the 'dig' command.
HNAME=news-15.net # Notorious spammer.
# HNAME=$HOST # Debug: test for localhost.
count=2 # Send only two pings.
if [[ `ping -c $count "$HNAME"` ]]
then
echo ""$HNAME" still up and broadcasting spam your way."
else
echo ""$HNAME" seems to be down. Pity."
fi
wget -p http://www.xyz23.com/file01.html
# The -p or --page-requisite option causes wget to fetch all files
#+ required to display the specified page.
wget -r ftp://ftp.xyz24.net/~bozo/project_files/ -O $SAVEFILE
# The -r option recursively follows and retrieves all links
#+ on the specified site.
wget -c ftp://ftp.xyz25.net/bozofiles/filename.tar.bz2
# The -c option lets wget resume an interrupted download.
# This works with ftp servers and many HTTP sites.
#!/bin/bash
# quote-fetch.sh: Download a stock quote.
E_NOPARAMS=86
if [ -z "$1" ] # Must specify a stock (symbol) to fetch.
then echo "Usage: `basename $0` stock-symbol"
exit $E_NOPARAMS
fi
stock_symbol=$1
file_suffix=.html
# Fetches an HTML file, so name it appropriately.
URL='http://finance.yahoo.com/q?s='
# Yahoo finance board, with stock query suffix.
# -----------------------------------------------------------
wget -O ${stock_symbol}${file_suffix} "${URL}${stock_symbol}"
# -----------------------------------------------------------
# To look up stuff on http://search.yahoo.com:
# -----------------------------------------------------------
# URL="http://search.yahoo.com/search?fr=ush-news&p=${query}"
# wget -O "$savefilename" "${URL}"
# -----------------------------------------------------------
# Saves a list of relevant URLs.
exit $?
# Exercises:
# ---------
#
# 1) Add a test to ensure the user running the script is on-line.
# (Hint: parse the output of 'ps -ax' for "ppp" or "connect."
#
# 2) Modify this script to fetch the local weather report,
#+ taking the user's zip code as an argument.
lynx -dump http://www.xyz23.com/file01.html &gt;$SAVEFILE
#!/bin/bash
# fc4upd.sh
# Script author: Frank Wang.
# Slight stylistic modifications by ABS Guide author.
# Used in ABS Guide with permission.
# Download Fedora Core 4 update from mirror site using rsync.
# Should also work for newer Fedora Cores -- 5, 6, . . .
# Only download latest package if multiple versions exist,
#+ to save space.
URL=rsync://distro.ibiblio.org/fedora-linux-core/updates/
# URL=rsync://ftp.kddilabs.jp/fedora/core/updates/
# URL=rsync://rsync.planetmirror.com/fedora-linux-core/updates/
DEST=${1:-/var/www/html/fedora/updates/}
LOG=/tmp/repo-update-$(/bin/date +%Y-%m-%d).txt
PID_FILE=/var/run/${0##*/}.pid
E_RETURN=85 # Something unexpected happened.
# General rsync options
# -r: recursive download
# -t: reserve time
# -v: verbose
OPTS="-rtv --delete-excluded --delete-after --partial"
# rsync include pattern
# Leading slash causes absolute path name match.
INCLUDE=(
"/4/i386/kde-i18n-Chinese*"
# ^ ^
# Quoting is necessary to prevent globbing.
)
# rsync exclude pattern
# Temporarily comment out unwanted pkgs using "#" . . .
EXCLUDE=(
/1
/2
/3
/testing
/4/SRPMS
/4/ppc
/4/x86_64
/4/i386/debug
"/4/i386/kde-i18n-*"
"/4/i386/openoffice.org-langpack-*"
"/4/i386/*i586.rpm"
"/4/i386/GFS-*"
"/4/i386/cman-*"
"/4/i386/dlm-*"
"/4/i386/gnbd-*"
"/4/i386/kernel-smp*"
# "/4/i386/kernel-xen*"
# "/4/i386/xen-*"
)
init () {
# Let pipe command return possible rsync error, e.g., stalled network.
set -o pipefail # Newly introduced in Bash, version 3.
TMP=${TMPDIR:-/tmp}/${0##*/}.$$ # Store refined download list.
trap "{
rm -f $TMP 2&gt;/dev/null
}" EXIT # Clear temporary file on exit.
}
check_pid () {
# Check if process exists.
if [ -s "$PID_FILE" ]; then
echo "PID file exists. Checking ..."
PID=$(/bin/egrep -o "^[[:digit:]]+" $PID_FILE)
if /bin/ps --pid $PID &&gt;/dev/null; then
echo "Process $PID found. ${0##*/} seems to be running!"
/usr/bin/logger -t ${0##*/} \
"Process $PID found. ${0##*/} seems to be running!"
exit $E_RETURN
fi
echo "Process $PID not found. Start new process . . ."
fi
}
# Set overall file update range starting from root or $URL,
#+ according to above patterns.
set_range () {
include=
exclude=
for p in "${INCLUDE[@]}"; do
include="$include --include \"$p\""
done
for p in "${EXCLUDE[@]}"; do
exclude="$exclude --exclude \"$p\""
done
}
# Retrieve and refine rsync update list.
get_list () {
echo $$ &gt; $PID_FILE || {
echo "Can't write to pid file $PID_FILE"
exit $E_RETURN
}
echo -n "Retrieving and refining update list . . ."
# Retrieve list -- 'eval' is needed to run rsync as a single command.
# $3 and $4 is the date and time of file creation.
# $5 is the full package name.
previous=
pre_file=
pre_date=0
eval /bin/nice /usr/bin/rsync \
-r $include $exclude $URL | \
egrep '^dr.x|^-r' | \
awk '{print $3, $4, $5}' | \
sort -k3 | \
{ while read line; do
# Get seconds since epoch, to filter out obsolete pkgs.
cur_date=$(date -d "$(echo $line | awk '{print $1, $2}')" +%s)
# echo $cur_date
# Get file name.
cur_file=$(echo $line | awk '{print $3}')
# echo $cur_file
# Get rpm pkg name from file name, if possible.
if [[ $cur_file == *rpm ]]; then
pkg_name=$(echo $cur_file | sed -r -e \
's/(^([^_-]+[_-])+)[[:digit:]]+\..*[_-].*$/\1/')
else
pkg_name=
fi
# echo $pkg_name
if [ -z "$pkg_name" ]; then # If not a rpm file,
echo $cur_file &gt;&gt; $TMP #+ then append to download list.
elif [ "$pkg_name" != "$previous" ]; then # A new pkg found.
echo $pre_file &gt;&gt; $TMP # Output latest file.
previous=$pkg_name # Save current.
pre_date=$cur_date
pre_file=$cur_file
elif [ "$cur_date" -gt "$pre_date" ]; then
# If same pkg, but newer,
pre_date=$cur_date #+ then update latest pointer.
pre_file=$cur_file
fi
done
echo $pre_file &gt;&gt; $TMP # TMP contains ALL
#+ of refined list now.
# echo "subshell=$BASH_SUBSHELL"
} # Bracket required here to let final "echo $pre_file &gt;&gt; $TMP"
# Remained in the same subshell ( 1 ) with the entire loop.
RET=$? # Get return code of the pipe command.
[ "$RET" -ne 0 ] && {
echo "List retrieving failed with code $RET"
exit $E_RETURN
}
echo "done"; echo
}
# Real rsync download part.
get_file () {
echo "Downloading..."
/bin/nice /usr/bin/rsync \
$OPTS \
--filter "merge,+/ $TMP" \
--exclude '*' \
$URL $DEST \
| /usr/bin/tee $LOG
RET=$?
# --filter merge,+/ is crucial for the intention.
# + modifier means include and / means absolute path.
# Then sorted list in $TMP will contain ascending dir name and
#+ prevent the following --exclude '*' from "shortcutting the circuit."
echo "Done"
rm -f $PID_FILE 2&gt;/dev/null
return $RET
}
# -------
# Main
init
check_pid
set_range
get_list
get_file
RET=$?
# -------
if [ "$RET" -eq 0 ]; then
/usr/bin/logger -t ${0##*/} "Fedora update mirrored successfully."
else
/usr/bin/logger -t ${0##*/} \
"Fedora update mirrored with failure code: $RET"
fi
exit $RET
#!/bin/bash
# remote.bash: Using ssh.
# This example by Michael Zick.
# Used with permission.
# Presumptions:
# ------------
# fd-2 isn't being captured ( '2&gt;/dev/null' ).
# ssh/sshd presumes stderr ('2') will display to user.
#
# sshd is running on your machine.
# For any 'standard' distribution, it probably is,
#+ and without any funky ssh-keygen having been done.
# Try ssh to your machine from the command-line:
#
# $ ssh $HOSTNAME
# Without extra set-up you'll be asked for your password.
# enter password
# when done, $ exit
#
# Did that work? If so, you're ready for more fun.
# Try ssh to your machine as 'root':
#
# $ ssh -l root $HOSTNAME
# When asked for password, enter root's, not yours.
# Last login: Tue Aug 10 20:25:49 2004 from localhost.localdomain
# Enter 'exit' when done.
# The above gives you an interactive shell.
# It is possible for sshd to be set up in a 'single command' mode,
#+ but that is beyond the scope of this example.
# The only thing to note is that the following will work in
#+ 'single command' mode.
# A basic, write stdout (local) command.
ls -l
# Now the same basic command on a remote machine.
# Pass a different 'USERNAME' 'HOSTNAME' if desired:
USER=${USERNAME:-$(whoami)}
HOST=${HOSTNAME:-$(hostname)}
# Now excute the above command-line on the remote host,
#+ with all transmissions encrypted.
ssh -l ${USER} ${HOST} " ls -l "
# The expected result is a listing of your username's home
#+ directory on the remote machine.
# To see any difference, run this script from somewhere
#+ other than your home directory.
# In other words, the Bash command is passed as a quoted line
#+ to the remote shell, which executes it on the remote machine.
# In this case, sshd does ' bash -c "ls -l" ' on your behalf.
# For information on topics such as not having to enter a
#+ password/passphrase for every command-line, see
#+ man ssh
#+ man ssh-keygen
#+ man sshd_config.
exit 0
#!/bin/sh
# self-mailer.sh: Self-mailing script
adr=${1:-`whoami`} # Default to current user, if not specified.
# Typing 'self-mailer.sh wiseguy@superdupergenius.com'
#+ sends this script to that addressee.
# Just 'self-mailer.sh' (no argument) sends the script
#+ to the person invoking it, for example, bozo@localhost.localdomain.
#
# For more on the ${parameter:-default} construct,
#+ see the "Parameter Substitution" section
#+ of the "Variables Revisited" chapter.
# ============================================================================
cat $0 | mail -s "Script \"`basename $0`\" has mailed itself to you." "$adr"
# ============================================================================
# --------------------------------------------
# Greetings from the self-mailing script.
# A mischievous person has run this script,
#+ which has caused it to mail itself to you.
# Apparently, some people have nothing better
#+ to do with their time.
# --------------------------------------------
echo "At `date`, script \"`basename $0`\" mailed to "$adr"."
exit 0
# Note that the "mailx" command (in "send" mode) may be substituted
#+ for "mail" ... but with somewhat different options.</pre>]
/dev/sda1 /mnt/flashdrive auto noauto,user,noatime 0 0
head -1 /dev/hdc
# head: cannot open '/dev/hdc' for reading: No medium found
# (No disc in the drive.)
# head: error reading '/dev/hdc': Input/output error
# (There is a disk in the drive, but it can't be read;
#+ possibly it's an unrecorded CDR blank.)
# Stream of characters and assorted gibberish
# (There is a pre-recorded disk in the drive,
#+ and this is raw output -- a stream of ASCII and binary data.)
# Here we see the wisdom of using 'head' to limit the output
#+ to manageable proportions, rather than 'cat' or something similar.
# Now, it's just a matter of checking/parsing the output and taking
#+ appropriate action.
#!/bin/bash
# This script must run with root permissions.
URL="time.nist.gov/13"
Time=$(cat </dev/tcp/"$URL")
UTC=$(echo "$Time" | awk '{print$3}') # Third field is UTC (GMT) time.
# Exercise: modify this for different time zones.
echo "UTC Time = "$UTC""
#!/bin/bash
# dev-tcp.sh: /dev/tcp redirection to check Internet connection.
# Script by Troy Engel.
# Used with permission.
TCP_HOST=news-15.net # A known spam-friendly ISP.
TCP_PORT=80 # Port 80 is http.
# Try to connect. (Somewhat similar to a 'ping' . . .)
echo "HEAD / HTTP/1.0" &gt;/dev/tcp/${TCP_HOST}/${TCP_PORT}
MYEXIT=$?
: <<EXPLANATION
If bash was compiled with --enable-net-redirections, it has the capability of
using a special character device for both TCP and UDP redirections. These
redirections are used identically as STDIN/STDOUT/STDERR. The device entries
are 30,36 for /dev/tcp:
mknod /dev/tcp c 30 36
&gt;From the bash reference:
/dev/tcp/host/port
If host is a valid hostname or Internet address, and port is an integer
port number or service name, Bash attempts to open a TCP connection to the
corresponding socket.
EXPLANATION
if [ "X$MYEXIT" = "X0" ]; then
echo "Connection successful. Exit code: $MYEXIT"
else
echo "Connection unsuccessful. Exit code: $MYEXIT"
fi
exit $MYEXIT
#!/bin/bash
# music.sh
# Music without external files
# Author: Antonio Macchi
# Used in ABS Guide with permission.
# /dev/dsp default = 8000 frames per second, 8 bits per frame (1 byte),
#+ 1 channel (mono)
duration=2000 # If 8000 bytes = 1 second, then 2000 = 1/4 second.
volume=$'\xc0' # Max volume = \xff (or \x00).
mute=$'\x80' # No volume = \x80 (the middle).
function mknote () # $1=Note Hz in bytes (e.g. A = 440Hz ::
{ #+ 8000 fps / 440 = 16 :: A = 16 bytes per second)
for t in `seq 0 $duration`
do
test $(( $t % $1 )) = 0 && echo -n $volume || echo -n $mute
done
}
e=`mknote 49`
g=`mknote 41`
a=`mknote 36`
b=`mknote 32`
c=`mknote 30`
cis=`mknote 29`
d=`mknote 27`
e2=`mknote 24`
n=`mknote 32767`
# European notation.
echo -n "$g$e2$d$c$d$c$a$g$n$g$e$n$g$e2$d$c$c$b$c$cis$n$cis$d \
$n$g$e2$d$c$d$c$a$g$n$g$e$n$g$a$d$c$b$a$b$c" &gt; /dev/dsp
# dsp = Digital Signal Processor
exit # A "bonny" example of an elegant shell script!</pre>]
[]
find ~/ -name 'core*' -exec rm {} \;
# Removes all core dump files from user's home directory.
find /home/bozo/projects -mtime -1
# ^ Note minus sign!
# Lists all files in /home/bozo/projects directory tree
#+ that were modified within the last day (current_day - 1).
#
find /home/bozo/projects -mtime 1
# Same as above, but modified *exactly* one day ago.
#
# mtime = last modification time of the target file
# ctime = last status change time (via 'chmod' or otherwise)
# atime = last access time
DIR=/home/bozo/junk_files
find "$DIR" -type f -atime +5 -exec rm {} \;
# ^ ^^
# Curly brackets are placeholder for the path name output by "find."
#
# Deletes all files in "/home/bozo/junk_files"
#+ that have not been accessed in *at least* 5 days (plus sign ... +5).
#
# "-type filetype", where
# f = regular file
# d = directory
# l = symbolic link, etc.
#
# (The 'find' manpage and info page have complete option listings.)
find /etc -exec grep '[0-9][0-9]*[.][0-9][0-9]*[.][0-9][0-9]*[.][0-9][0-9]*' {} \;
# Finds all IP addresses (xxx.xxx.xxx.xxx) in /etc directory files.
# There a few extraneous hits. Can they be filtered out?
# Possibly by:
find /etc -type f -exec cat '{}' \; | tr -c '.[:digit:]' '\n' \
| grep '^[^.][^.]*\.[^.][^.]*\.[^.][^.]*\.[^.][^.]*$'
#
# [:digit:] is one of the character classes
#+ introduced with the POSIX 1003.2 standard.
# Thanks, Stéphane Chazelas.
#!/bin/bash
# badname.sh
# Delete filenames in current directory containing bad characters.
for filename in *
do
badname=`echo "$filename" | sed -n /[\+\{\;\"\\\=\?~\(\)\<\&gt;\&\*\|\$]/p`
# badname=`echo "$filename" | sed -n '/[+{;"\=?~()<&gt;&*|$]/p'` also works.
# Deletes files containing these nasties: + { ; " \ = ? ~ ( ) < &gt; & * | $
#
rm $badname 2&gt;/dev/null
# ^^^^^^^^^^^ Error messages deep-sixed.
done
# Now, take care of files containing all manner of whitespace.
find . -name "* *" -exec rm -f {} \;
# The path name of the file that _find_ finds replaces the "{}".
# The '\' ensures that the ';' is interpreted literally, as end of command.
exit 0
#---------------------------------------------------------------------
# Commands below this line will not execute because of _exit_ command.
# An alternative to the above script:
find . -name '*[+{;"\\=?~()<&gt;&*|$ ]*' -maxdepth 0 \
-exec rm -f '{}' \;
# The "-maxdepth 0" option ensures that _find_ will not search
#+ subdirectories below $PWD.
# (Thanks, S.C.)
#!/bin/bash
# idelete.sh: Deleting a file by its inode number.
# This is useful when a filename starts with an illegal character,
#+ such as ? or -.
ARGCOUNT=1 # Filename arg must be passed to script.
E_WRONGARGS=70
E_FILE_NOT_EXIST=71
E_CHANGED_MIND=72
if [ $# -ne "$ARGCOUNT" ]
then
echo "Usage: `basename $0` filename"
exit $E_WRONGARGS
fi
if [ ! -e "$1" ]
then
echo "File \""$1"\" does not exist."
exit $E_FILE_NOT_EXIST
fi
inum=`ls -i | grep "$1" | awk '{print $1}'`
# inum = inode (index node) number of file
# -----------------------------------------------------------------------
# Every file has an inode, a record that holds its physical address info.
# -----------------------------------------------------------------------
echo; echo -n "Are you absolutely sure you want to delete \"$1\" (y/n)? "
# The '-v' option to 'rm' also asks this.
read answer
case "$answer" in
[nN]) echo "Changed your mind, huh?"
exit $E_CHANGED_MIND
;;
*) echo "Deleting file \"$1\".";;
esac
find . -inum $inum -exec rm {} \;
# ^^
# Curly brackets are placeholder
#+ for text output by "find."
echo "File "\"$1"\" deleted!"
exit 0
#!/bin/bash
# Find suid root files.
# A strange suid file might indicate a security hole,
#+ or even a system intrusion.
directory="/usr/sbin"
# Might also try /sbin, /bin, /usr/bin, /usr/local/bin, etc.
permissions="+4000" # suid root (dangerous!)
for file in $( find "$directory" -perm "$permissions" )
do
ls -ltF --author "$file"
done
cat /proc/"$pid"/"$OPTION" | xargs -0 echo
# Formats output: ^^^^^^^^^^^^^^^
# From Han Holl's fixup of "get-commandline.sh"
#+ script in "/dev and /proc" chapter.
#!/bin/bash
ls *gif | xargs -t -n1 -P2 gif2png
# Converts all the gif images in current directory to png.
# Options:
# =======
# -t Print command to stderr.
# -n1 At most 1 argument per command line.
# -P2 Run up to 2 processes simultaneously.
# Thank you, Roberto Polli, for the inspiration.
#!/bin/bash
# Generates a log file in current directory
# from the tail end of /var/log/messages.
# Note: /var/log/messages must be world readable
# if this script invoked by an ordinary user.
# #root chmod 644 /var/log/messages
LINES=5
( date; uname -a ) &gt;&gt;logfile
# Time and machine name
echo ---------------------------------------------------------- &gt;&gt;logfile
tail -n $LINES /var/log/messages | xargs | fmt -s &gt;&gt;logfile
echo &gt;&gt;logfile
echo &gt;&gt;logfile
exit 0
# Note:
# ----
# As Frank Wang points out,
#+ unmatched quotes (either single or double quotes) in the source file
#+ may give xargs indigestion.
#
# He suggests the following substitution for line 15:
# tail -n $LINES /var/log/messages | tr -d "\"'" | xargs | fmt -s &gt;&gt;logfile
# Exercise:
# --------
# Modify this script to track changes in /var/log/messages at intervals
#+ of 20 minutes.
# Hint: Use the "watch" command.
#!/bin/bash
# copydir.sh
# Copy (verbose) all files in current directory ($PWD)
#+ to directory specified on command-line.
E_NOARGS=85
if [ -z "$1" ] # Exit if no argument given.
then
echo "Usage: `basename $0` directory-to-copy-to"
exit $E_NOARGS
fi
ls . | xargs -i -t cp ./{} $1
# ^^ ^^ ^^
# -t is "verbose" (output command-line to stderr) option.
# -i is "replace strings" option.
# {} is a placeholder for output text.
# This is similar to the use of a curly-bracket pair in "find."
#
# List the files in current directory (ls .),
#+ pass the output of "ls" as arguments to "xargs" (-i -t options),
#+ then copy (cp) these arguments ({}) to new directory ($1).
#
# The net result is the exact equivalent of
#+ cp * $1
#+ unless any of the filenames has embedded "whitespace" characters.
exit 0
#!/bin/bash
# kill-byname.sh: Killing processes by name.
# Compare this script with kill-process.sh.
# For instance,
#+ try "./kill-byname.sh xterm" --
#+ and watch all the xterms on your desktop disappear.
# Warning:
# -------
# This is a fairly dangerous script.
# Running it carelessly (especially as root)
#+ can cause data loss and other undesirable effects.
E_BADARGS=66
if test -z "$1" # No command-line arg supplied?
then
echo "Usage: `basename $0` Process(es)_to_kill"
exit $E_BADARGS
fi
PROCESS_NAME="$1"
ps ax | grep "$PROCESS_NAME" | awk '{print $1}' | xargs -i kill {} 2&&gt;/dev/null
# ^^ ^^
# ---------------------------------------------------------------
# Notes:
# -i is the "replace strings" option to xargs.
# The curly brackets are the placeholder for the replacement.
# 2&&gt;/dev/null suppresses unwanted error messages.
#
# Can grep "$PROCESS_NAME" be replaced by pidof "$PROCESS_NAME"?
# ---------------------------------------------------------------
exit $?
# The "killall" command has the same effect as this script,
#+ but using it is not quite as educational.
#!/bin/bash
# wf2.sh: Crude word frequency analysis on a text file.
# Uses 'xargs' to decompose lines of text into single words.
# Compare this example to the "wf.sh" script later on.
# Check for input file on command-line.
ARGS=1
E_BADARGS=85
E_NOFILE=86
if [ $# -ne "$ARGS" ]
# Correct number of arguments passed to script?
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS
fi
if [ ! -f "$1" ] # Does file exist?
then
echo "File \"$1\" does not exist."
exit $E_NOFILE
fi
#####################################################
cat "$1" | xargs -n1 | \
# List the file, one word per line.
tr A-Z a-z | \
# Shift characters to lowercase.
sed -e 's/\.//g' -e 's/\,//g' -e 's/ /\
/g' | \
# Filter out periods and commas, and
#+ change space between words to linefeed,
sort | uniq -c | sort -nr
# Finally remove duplicates, prefix occurrence count
#+ and sort numerically.
#####################################################
# This does the same job as the "wf.sh" example,
#+ but a bit more ponderously, and it runs more slowly (why?).
exit $?
#!/bin/bash
# Demonstrating some of the uses of 'expr'
# =======================================
echo
# Arithmetic Operators
# ---------- ---------
echo "Arithmetic Operators"
echo
a=`expr 5 + 3`
echo "5 + 3 = $a"
a=`expr $a + 1`
echo
echo "a + 1 = $a"
echo "(incrementing a variable)"
a=`expr 5 % 3`
# modulo
echo
echo "5 mod 3 = $a"
echo
echo
# Logical Operators
# ------- ---------
# Returns 1 if true, 0 if false,
#+ opposite of normal Bash convention.
echo "Logical Operators"
echo
x=24
y=25
b=`expr $x = $y` # Test equality.
echo "b = $b" # 0 ( $x -ne $y )
echo
a=3
b=`expr $a \&gt; 10`
echo 'b=`expr $a \&gt; 10`, therefore...'
echo "If a &gt; 10, b = 0 (false)"
echo "b = $b" # 0 ( 3 ! -gt 10 )
echo
b=`expr $a \< 10`
echo "If a < 10, b = 1 (true)"
echo "b = $b" # 1 ( 3 -lt 10 )
echo
# Note escaping of operators.
b=`expr $a \<= 3`
echo "If a <= 3, b = 1 (true)"
echo "b = $b" # 1 ( 3 -le 3 )
# There is also a "\&gt;=" operator (greater than or equal to).
echo
echo
# String Operators
# ------ ---------
echo "String Operators"
echo
a=1234zipper43231
echo "The string being operated upon is \"$a\"."
# length: length of string
b=`expr length $a`
echo "Length of \"$a\" is $b."
# index: position of first character in substring
# that matches a character in string
b=`expr index $a 23`
echo "Numerical position of first \"2\" in \"$a\" is \"$b\"."
# substr: extract substring, starting position & length specified
b=`expr substr $a 2 6`
echo "Substring of \"$a\", starting at position 2,\
and 6 chars long is \"$b\"."
# The default behavior of the 'match' operations is to
#+ search for the specified match at the BEGINNING of the string.
#
# Using Regular Expressions ...
b=`expr match "$a" '[0-9]*'` # Numerical count.
echo Number of digits at the beginning of \"$a\" is $b.
b=`expr match "$a" '\([0-9]*\)'` # Note that escaped parentheses
# == == #+ trigger substring match.
echo "The digits at the beginning of \"$a\" are \"$b\"."
echo
exit 0
#!/bin/bash
echo
echo "String operations using \"expr \$string : \" construct"
echo "==================================================="
echo
a=1234zipper5FLIPPER43231
echo "The string being operated upon is \"`expr "$a" : '\(.*\)'`\"."
# Escaped parentheses grouping operator. == ==
# ***************************
#+ Escaped parentheses
#+ match a substring
# ***************************
# If no escaped parentheses ...
#+ then 'expr' converts the string operand to an integer.
echo "Length of \"$a\" is `expr "$a" : '.*'`." # Length of string
echo "Number of digits at the beginning of \"$a\" is `expr "$a" : '[0-9]*'`."
# ------------------------------------------------------------------------- #
echo
echo "The digits at the beginning of \"$a\" are `expr "$a" : '\([0-9]*\)'`."
# == ==
echo "The first 7 characters of \"$a\" are `expr "$a" : '\(.......\)'`."
# ===== == ==
# Again, escaped parentheses force a substring match.
#
echo "The last 7 characters of \"$a\" are `expr "$a" : '.*\(.......\)'`."
# ==== end of string operator ^^
# (In fact, means skip over one or more of any characters until specified
#+ substring found.)
echo
exit 0
# Strip the whitespace from the beginning and end.
LRFDATE=`expr "$LRFDATE" : '[[:space:]]*\(.*\)[[:space:]]*$'`
# From Peter Knowles' "booklistgen.sh" script
#+ for converting files to Sony Librie/PRS-50X format.
# (http://booklistgensh.peterknowles.com)</pre>]
while [ -n "$remaining" -a "$retry" -gt 0 ]; do
# This looks rather daunting at first glance.
# Separate the conditions:
while [ -n "$remaining" -a "$retry" -gt 0 ]; do
# --condition 1-- ^^ --condition 2-
# If variable "$remaining" is not zero length
#+ AND (-a)
#+ variable "$retry" is greater-than zero
#+ then
#+ the [ expresion-within-condition-brackets ] returns success (0)
#+ and the while-loop executes an iteration.
# ==============================================================
# Evaluate "condition 1" and "condition 2" ***before***
#+ ANDing them. Why? Because the AND (-a) has a lower precedence
#+ than the -n and -gt operators,
#+ and therefore gets evaluated *last*.
#################################################################
if [ -f /etc/sysconfig/i18n -a -z "${NOLOCALE:-}" ] ; then
# Again, separate the conditions:
if [ -f /etc/sysconfig/i18n -a -z "${NOLOCALE:-}" ] ; then
# --condition 1--------- ^^ --condition 2-----
# If file "/etc/sysconfig/i18n" exists
#+ AND (-a)
#+ variable $NOLOCALE is zero length
#+ then
#+ the [ test-expresion-within-condition-brackets ] returns success (0)
#+ and the commands following execute.
#
# As before, the AND (-a) gets evaluated *last*
#+ because it has the lowest precedence of the operators within
#+ the test brackets.
# ==============================================================
# Note:
# ${NOLOCALE:-} is a parameter expansion that seems redundant.
# But, if $NOLOCALE has not been declared, it gets set to *null*,
#+ in effect declaring it.
# This makes a difference in some contexts.
if [ "$v1" -gt "$v2" -o "$v1" -lt "$v2" -a -e "$filename" ]
# Unclear what's going on here...
if [[ "$v1" -gt "$v2" ]] || [[ "$v1" -lt "$v2" ]] && [[ -e "$filename" ]]
# Much better -- the condition tests are grouped in logical sections.</pre>]
TEST FILE: tstfile # No match.
# No match.
Run grep "1133*" on this file. # Match.
# No match.
# No match.
This line contains the number 113. # Match.
This line contains the number 13. # No match.
This line contains the number 133. # No match.
This line contains the number 1133. # Match.
This line contains the number 113312. # Match.
This line contains the number 1112. # No match.
This line contains the number 113312312. # Match.
This line contains no numbers at all. # No match.
# GNU versions of sed and awk can use "+",
# but it needs to be escaped.
echo a111b | sed -ne '/a1\+b/p'
echo a111b | grep 'a1\+b'
echo a111b | gawk '/a1+b/'
# All of above are equivalent.
# Thanks, S.C.
# ...
if [[ $arow =~ [[:digit:]] ]] # Numerical input?
then # POSIX char class
if [[ $acol =~ [[:alpha:]] ]] # Number followed by a letter? Illegal!
# ...
# From ktour.sh example script.
#!/bin/bash
sed -e 'N;s/.*/[&]/' << EOF # Here Document
line1
line2
EOF
# OUTPUT:
# [line1
# line2]
echo
awk '{ $0=$1 "\n" $2; if (/line.1/) {print}}' << EOF
line 1
line 2
EOF
# OUTPUT:
# line
# 1
# Thanks, S.C.
exit 0</pre>]
IFS="$(printf '\n\t')" # Remove space.
# Correct glob use:
# Always use for-loop, prefix glob, check if exists file.
for file in ./* ; do # Use ./* ... NEVER bare *
if [ -e "$file" ] ; then # Check whether file exists.
COMMAND ... "$file" ...
fi
done
# This example taken from David Wheeler's site, with permission.
~/[.]bashrc # Will not expand to ~/.bashrc
~/?bashrc # Neither will this.
# Wild cards and metacharacters will NOT
#+ expand to a dot in globbing.
~/.[b]ashrc # Will expand to ~/.bashrc
~/.ba?hrc # Likewise.
~/.bashr* # Likewise.
# Setting the "dotglob" option turns this off.
# Thanks, S.C.</pre>]
List="one two three"
for a in $List # Splits the variable in parts at whitespace.
do
echo "$a"
done
# one
# two
# three
echo "---"
for a in "$List" # Preserves whitespace in a single variable.
do # ^ ^
echo "$a"
done
# one two three
variable1="a variable containing five words"
COMMAND This is $variable1 # Executes COMMAND with 7 arguments:
# "This" "is" "a" "variable" "containing" "five" "words"
COMMAND "This is $variable1" # Executes COMMAND with 1 argument:
# "This is a variable containing five words"
variable2="" # Empty.
COMMAND $variable2 $variable2 $variable2
# Executes COMMAND with no arguments.
COMMAND "$variable2" "$variable2" "$variable2"
# Executes COMMAND with 3 empty arguments.
COMMAND "$variable2 $variable2 $variable2"
# Executes COMMAND with 1 argument (2 spaces).
# Thanks, Stéphane Chazelas.
#!/bin/bash
# weirdvars.sh: Echoing weird variables.
echo
var="'(]\\{}\$\""
echo $var # '(]\{}$"
echo "$var" # '(]\{}$" Doesn't make a difference.
echo
IFS='\'
echo $var # '(] {}$" \ converted to space. Why?
echo "$var" # '(]\{}$"
# Examples above supplied by Stephane Chazelas.
echo
var2="\\\\\""
echo $var2 # "
echo "$var2" # \\"
echo
# But ... var2="\\\\"" is illegal. Why?
var3='\\\\'
echo "$var3" # \\\\
# Strong quoting works, though.
# ************************************************************ #
# As the first example above shows, nesting quotes is permitted.
echo "$(echo '"')" # "
# ^ ^
# At times this comes in useful.
var1="Two bits"
echo "\$var1 = "$var1"" # $var1 = Two bits
# ^ ^
# Or, as Chris Hiestand points out ...
if [[ "$(du "$My_File1")" -gt "$(du "$My_File2")" ]]
# ^ ^ ^ ^ ^ ^ ^ ^
then
...
fi
# ************************************************************ #
echo "Why can't I write 's between single quotes"
echo
# The roundabout method.
echo 'Why can'\''t I write '"'"'s between single quotes'
# |-------| |----------| |-----------------------|
# Three single-quoted strings, with escaped and quoted single quotes between.
# This example courtesy of Stéphane Chazelas.</pre>]
[]
#!/bin/bash
# alias.sh
shopt -s expand_aliases
# Must set this option, else script will not expand aliases.
# First, some fun.
alias Jesse_James='echo "\"Alias Jesse James\" was a 1959 comedy starring Bob Hope."'
Jesse_James
echo; echo; echo;
alias ll="ls -l"
# May use either single (') or double (") quotes to define an alias.
echo "Trying aliased \"ll\":"
ll /usr/X11R6/bin/mk* #* Alias works.
echo
directory=/usr/X11R6/bin/
prefix=mk* # See if wild card causes problems.
echo "Variables \"directory\" + \"prefix\" = $directory$prefix"
echo
alias lll="ls -l $directory$prefix"
echo "Trying aliased \"lll\":"
lll # Long listing of all files in /usr/X11R6/bin stating with mk.
# An alias can handle concatenated variables -- including wild card -- o.k.
TRUE=1
echo
if [ TRUE ]
then
alias rr="ls -l"
echo "Trying aliased \"rr\" within if/then statement:"
rr /usr/X11R6/bin/mk* #* Error message results!
# Aliases not expanded within compound statements.
echo "However, previously expanded alias still recognized:"
ll /usr/X11R6/bin/mk*
fi
echo
count=0
while [ $count -lt 3 ]
do
alias rrr="ls -l"
echo "Trying aliased \"rrr\" within \"while\" loop:"
rrr /usr/X11R6/bin/mk* #* Alias will not expand here either.
# alias.sh: line 57: rrr: command not found
let count+=1
done
echo; echo
alias xyz='cat $0' # Script lists itself.
# Note strong quotes.
xyz
# This seems to work,
#+ although the Bash documentation suggests that it shouldn't.
#
# However, as Steve Jacobson points out,
#+ the "$0" parameter expands immediately upon declaration of the alias.
exit 0
#!/bin/bash
# unalias.sh
shopt -s expand_aliases # Enables alias expansion.
alias llm='ls -al | more'
llm
echo
unalias llm # Unset alias.
llm
# Error message results, since 'llm' no longer recognized.
exit 0</pre>]
[]
z=`expr $z + 3` # The 'expr' command performs the expansion.
z=$(($z+3))
z=$((z+3)) # Also correct.
# Within double parentheses,
#+ parameter dereferencing
#+ is optional.
# $((EXPRESSION)) is arithmetic expansion. # Not to be confused with
#+ command substitution.
# You may also use operations within double parentheses without assignment.
n=0
echo "n = $n" # n = 0
(( n += 1 )) # Increment.
# (( $n += 1 )) is incorrect!
echo "n = $n" # n = 1
let z=z+3
let "z += 3" # Quotes permit the use of spaces in variable assignment.
# The 'let' operator actually performs arithmetic evaluation,
#+ rather than expansion.</pre>]
#!/bin/bash
# ex9.sh
# Variables: assignment and substitution
a=375
hello=$a
# ^ ^
#-------------------------------------------------------------------------
# No space permitted on either side of = sign when initializing variables.
# What happens if there is a space?
# "VARIABLE =value"
# ^
#% Script tries to run "VARIABLE" command with one argument, "=value".
# "VARIABLE= value"
# ^
#% Script tries to run "value" command with
#+ the environmental variable "VARIABLE" set to "".
#-------------------------------------------------------------------------
echo hello # hello
# Not a variable reference, just the string "hello" ...
echo $hello # 375
# ^ This *is* a variable reference.
echo ${hello} # 375
# Likewise a variable reference, as above.
# Quoting . . .
echo "$hello" # 375
echo "${hello}" # 375
echo
hello="A B C D"
echo $hello # A B C D
echo "$hello" # A B C D
# As we see, echo $hello and echo "$hello" give different results.
# =======================================
# Quoting a variable preserves whitespace.
# =======================================
echo
echo '$hello' # $hello
# ^ ^
# Variable referencing disabled (escaped) by single quotes,
#+ which causes the "$" to be interpreted literally.
# Notice the effect of different types of quoting.
hello= # Setting it to a null value.
echo "\$hello (null value) = $hello" # $hello (null value) =
# Note that setting a variable to a null value is not the same as
#+ unsetting it, although the end result is the same (see below).
# --------------------------------------------------------------
# It is permissible to set multiple variables on the same line,
#+ if separated by white space.
# Caution, this may reduce legibility, and may not be portable.
var1=21 var2=22 var3=$V3
echo
echo "var1=$var1 var2=$var2 var3=$var3"
# May cause problems with legacy versions of "sh" . . .
# --------------------------------------------------------------
echo; echo
numbers="one two three"
# ^ ^
other_numbers="1 2 3"
# ^ ^
# If there is whitespace embedded within a variable,
#+ then quotes are necessary.
# other_numbers=1 2 3 # Gives an error message.
echo "numbers = $numbers"
echo "other_numbers = $other_numbers" # other_numbers = 1 2 3
# Escaping the whitespace also works.
mixed_bag=2\ ---\ Whatever
# ^ ^ Space after escape (\).
echo "$mixed_bag" # 2 --- Whatever
echo; echo
echo "uninitialized_variable = $uninitialized_variable"
# Uninitialized variable has null value (no value at all!).
uninitialized_variable= # Declaring, but not initializing it --
#+ same as setting it to a null value, as above.
echo "uninitialized_variable = $uninitialized_variable"
# It still has a null value.
uninitialized_variable=23 # Set it.
unset uninitialized_variable # Unset it.
echo "uninitialized_variable = $uninitialized_variable"
# uninitialized_variable =
# It still has a null value.
echo
exit 0
if [ -z "$unassigned" ]
then
echo "\$unassigned is NULL."
fi # $unassigned is NULL.
echo "$uninitialized" # (blank line)
let "uninitialized += 5" # Add 5 to it.
echo "$uninitialized" # 5
# Conclusion:
# An uninitialized variable has no value,
#+ however it evaluates as 0 in an arithmetic operation.</pre>]
# Cleanup
# Run as root, of course.
cd /var/log
cat /dev/null &gt; messages
cat /dev/null &gt; wtmp
echo "Log files cleaned up."
#!/bin/bash
# Proper header for a Bash script.
# Cleanup, version 2
# Run as root, of course.
# Insert code here to print error message and exit if not root.
LOG_DIR=/var/log
# Variables are better than hard-coded values.
cd $LOG_DIR
cat /dev/null &gt; messages
cat /dev/null &gt; wtmp
echo "Logs cleaned up."
exit # The right and proper method of "exiting" from a script.
# A bare "exit" (no parameter) returns the exit status
#+ of the preceding command.
#!/bin/bash
# Cleanup, version 3
# Warning:
# -------
# This script uses quite a number of features that will be explained
#+ later on.
# By the time you've finished the first half of the book,
#+ there should be nothing mysterious about it.
LOG_DIR=/var/log
ROOT_UID=0 # Only users with $UID 0 have root privileges.
LINES=50 # Default number of lines saved.
E_XCD=86 # Can't change directory?
E_NOTROOT=87 # Non-root exit error.
# Run as root, of course.
if [ "$UID" -ne "$ROOT_UID" ]
then
echo "Must be root to run this script."
exit $E_NOTROOT
fi
if [ -n "$1" ]
# Test whether command-line argument is present (non-empty).
then
lines=$1
else
lines=$LINES # Default, if not specified on command-line.
fi
# Stephane Chazelas suggests the following,
#+ as a better way of checking command-line arguments,
#+ but this is still a bit advanced for this stage of the tutorial.
#
# E_WRONGARGS=85 # Non-numerical argument (bad argument format).
#
# case "$1" in
# "" ) lines=50;;
# *[!0-9]*) echo "Usage: `basename $0` lines-to-cleanup";
# exit $E_WRONGARGS;;
# * ) lines=$1;;
# esac
#
#* Skip ahead to "Loops" chapter to decipher all this.
cd $LOG_DIR
if [ `pwd` != "$LOG_DIR" ] # or if [ "$PWD" != "$LOG_DIR" ]
# Not in /var/log?
then
echo "Can't change to $LOG_DIR."
exit $E_XCD
fi # Doublecheck if in right directory before messing with log file.
# Far more efficient is:
#
# cd /var/log || {
# echo "Cannot change to necessary directory." &gt;&2
# exit $E_XCD;
# }
tail -n $lines messages &gt; mesg.temp # Save last section of message log file.
mv mesg.temp messages # Rename it as system log file.
# cat /dev/null &gt; messages
#* No longer needed, as the above method is safer.
cat /dev/null &gt; wtmp # ': &gt; wtmp' and '&gt; wtmp' have the same effect.
echo "Log files cleaned up."
# Note that there are other log files in /var/log not affected
#+ by this script.
exit 0
# A zero return value from the script upon exit indicates success
#+ to the shell.
#!/bin/sh
#!/bin/bash
#!/usr/bin/perl
#!/usr/bin/tcl
#!/bin/sed -f
#!/bin/awk -f
E_WRONG_ARGS=85
script_parameters="-a -h -m -z"
# -a = all, -h = help, etc.
if [ $# -ne $Number_of_expected_args ]
then
echo "Usage: `basename $0` $script_parameters"
# `basename $0` is the script's filename.
exit $E_WRONG_ARGS
fi
#!/bin/bash
echo "Part 1 of script."
a=1
#!/bin/bash
# This does *not* launch a new script.
echo "Part 2 of script."
echo $a # Value of $a stays at 1.
#!/bin/rm
# Self-deleting script.
# Nothing much seems to happen when you run this... except that the file disappears.
WHATEVER=85
echo "This line will never print (betcha!)."
exit $WHATEVER # Doesn't matter. The script will not exit here.
# Try an echo $? after script termination.
# You'll get a 0, not a 85.</pre>]
[]
[]
[]
cat "$file" | grep "$word"
grep "$word" "$file"
# The above command-lines have an identical effect,
#+ but the second runs faster since it launches one fewer subprocess.
export LC_ALL=C
[specifies the locale as ANSI C,
thereby disabling Unicode support]
[In an example script ...]
Without [Unicode support]:
erik@erik-desktop:~/capture$ time ./cap-ngrep.sh
live2.pcap &gt; out.txt
real 0m20.483s
user 1m34.470s
sys 0m12.869s
With [Unicode support]:
erik@erik-desktop:~/capture$ time ./cap-ngrep.sh
live2.pcap &gt; out.txt
real 0m50.232s
user 3m51.118s
sys 0m11.221s
A large part of the overhead that is optimized is, I believe,
regex match using [[ string =~ REGEX ]],
but it may help with other portions of the code as well.
I hadn't [seen it] mentioned that this optimization helped
with Bash, but I had seen it helped with "grep,"
so why not try?
Math tests
math via $(( ))
real 0m0.294s
user 0m0.288s
sys 0m0.008s
math via expr:
real 1m17.879s # Much slower!
user 0m3.600s
sys 0m8.765s
math via let:
real 0m0.364s
user 0m0.372s
sys 0m0.000s
Test using "case" construct:
real 0m0.329s
user 0m0.320s
sys 0m0.000s
Test with if [], no quotes:
real 0m0.438s
user 0m0.432s
sys 0m0.008s
Test with if [], quotes:
real 0m0.476s
user 0m0.452s
sys 0m0.024s
Test with if [], using -eq:
real 0m0.457s
user 0m0.456s
sys 0m0.000s
Assignment tests
Assigning a simple variable
real 0m0.418s
user 0m0.416s
sys 0m0.004s
Assigning a numeric index array entry
real 0m0.582s
user 0m0.564s
sys 0m0.016s
Overwriting a numeric index array entry
real 0m21.931s
user 0m21.913s
sys 0m0.016s
Linear reading of numeric index array
real 0m0.422s
user 0m0.416s
sys 0m0.004s
Assigning an associative array entry
real 0m1.800s
user 0m1.796s
sys 0m0.004s
Overwriting an associative array entry
real 0m1.798s
user 0m1.784s
sys 0m0.012s
Linear reading an associative array entry
real 0m0.420s
user 0m0.420s
sys 0m0.000s
Assigning a random number to a simple variable
real 0m0.402s
user 0m0.388s
sys 0m0.016s
Assigning a sparse numeric index array entry randomly into 64k cells
real 0m12.678s
user 0m12.649s
sys 0m0.028s
Reading sparse numeric index array entry
real 0m0.087s
user 0m0.084s
sys 0m0.000s
Assigning a sparse associative array entry randomly into 64k cells
real 0m0.698s
user 0m0.696s
sys 0m0.004s
Reading sparse associative index array entry
real 0m0.083s
user 0m0.084s
sys 0m0.000s</pre>]
#!/usr/bin/env bash
#-----------------------------------------------------------
# Management of PATH, LD_LIBRARY_PATH, MANPATH variables...
# By Emmanuel Rouat <no-email&gt;
# (Inspired by the bash documentation 'pathfuncs' and on
# discussions found on stackoverflow:
# http://stackoverflow.com/questions/370047/
# http://stackoverflow.com/questions/273909/#346860 )
# Last modified: Sat Sep 22 12:01:55 CEST 2012
#
# The following functions handle spaces correctly.
# These functions belong in .bash_profile rather than in
# .bashrc, I guess.
#
# The modular aspect of these functions should make it easy
# to expand them to handle path substitutions instead
# of path removal etc....
#
# See http://www.catonmat.net/blog/awk-one-liners-explained-part-two/
# (item 43) for an explanation of the 'duplicate-entries' removal
# (it's a nice trick!)
#-----------------------------------------------------------
# Show $@ (usually PATH) as list.
function p_show() { local p="$@" && for p; do [[ ${!p} ]] &&
echo -e ${!p//:/\\n}; done }
# Filter out empty lines, multiple/trailing slashes, and duplicate entries.
function p_filter()
{ awk '/^[ \t]*$/ {next} {sub(/\/+$/, "");gsub(/\/+/, "/")}!x[$0]++' ;}
# Rebuild list of items into ':' separated word (PATH-like).
function p_build() { paste -sd: ;}
# Clean $1 (typically PATH) and rebuild it
function p_clean()
{ local p=${1} && eval ${p}='$(p_show ${p} | p_filter | p_build)' ;}
# Remove $1 from $2 (found on stackoverflow, with modifications).
function p_rm()
{ local d=$(echo $1 | p_filter) p=${2} &&
eval ${p}='$(p_show ${p} | p_filter | grep -xv "${d}" | p_build)' ;}
# Same as previous, but filters on a pattern (dangerous...
#+ don't use 'bin' or '/' as pattern!).
function p_rmpat()
{ local d=$(echo $1 | p_filter) p=${2} && eval ${p}='$(p_show ${p} |
p_filter | grep -v "${d}" | p_build)' ;}
# Delete $1 from $2 and append it cleanly.
function p_append()
{ local d=$(echo $1 | p_filter) p=${2} && p_rm "${d}" ${p} &&
eval ${p}='$(p_show ${p} d | p_build)' ;}
# Delete $1 from $2 and prepend it cleanly.
function p_prepend()
{ local d=$(echo $1 | p_filter) p=${2} && p_rm "${d}" ${p} &&
eval ${p}='$(p_show d ${p} | p_build)' ;}
# Some tests:
echo
MYPATH="/bin:/usr/bin/:/bin://bin/"
p_append "/project//my project/bin" MYPATH
echo "Append '/project//my project/bin' to '/bin:/usr/bin/:/bin://bin/'"
echo "(result should be: /bin:/usr/bin:/project/my project/bin)"
echo $MYPATH
echo
MYOTHERPATH="/bin:/usr/bin/:/bin:/project//my project/bin"
p_prepend "/project//my project/bin" MYOTHERPATH
echo "Prepend '/project//my project/bin' \
to '/bin:/usr/bin/:/bin:/project//my project/bin/'"
echo "(result should be: /project/my project/bin:/bin:/usr/bin)"
echo $MYOTHERPATH
echo
p_prepend "/project//my project/bin" FOOPATH # FOOPATH doesn't exist.
echo "Prepend '/project//my project/bin' to an unset variable"
echo "(result should be: /project/my project/bin)"
echo $FOOPATH
echo
BARPATH="/a:/b/://b c://a:/my local pub"
p_clean BARPATH
echo "Clean BARPATH='/a:/b/://b c://a:/my local pub'"
echo "(result should be: /a:/b:/b c:/my local pub)"
echo $BARPATH
Doing it correctly: A quick summary
by David Wheeler
http://www.dwheeler.com/essays/filenames-in-shell.html
So, how can you process filenames correctly in shell? Here's a quick
summary about how to do it correctly, for the impatient who "just want the
answer". In short: Double-quote to use "$variable" instead of $variable,
set IFS to just newline and tab, prefix all globs/filenames so they cannot
begin with "-" when expanded, and use one of a few templates that work
correctly. Here are some of those templates that work correctly:
IFS="$(printf '\n\t')"
# Remove SPACE, so filenames with spaces work well.
# Correct glob use:
#+ always use "for" loop, prefix glob, check for existence:
for file in ./* ; do # Use "./*" ... NEVER bare "*" ...
if [ -e "$file" ] ; then # Make sure it isn't an empty match.
COMMAND ... "$file" ...
fi
done
# Correct glob use, but requires nonstandard bash extension.
shopt -s nullglob # Bash extension,
#+ so that empty glob matches will work.
for file in ./* ; do # Use "./*", NEVER bare "*"
COMMAND ... "$file" ...
done
# These handle all filenames correctly;
#+ can be unwieldy if COMMAND is large:
find ... -exec COMMAND... {} \;
find ... -exec COMMAND... {} \+ # If multiple files are okay for COMMAND.
# This skips filenames with control characters
#+ (including tab and newline).
IFS="$(printf '\n\t')"
controlchars="$(printf '*[\001-\037\177]*')"
for file in $(find . ! -name "$controlchars"') ; do
COMMAND "$file" ...
done
# Okay if filenames can't contain tabs or newlines --
#+ beware the assumption.
IFS="$(printf '\n\t')"
for file in $(find .) ; do
COMMAND "$file" ...
done
# Requires nonstandard but common extensions in find and xargs:
find . -print0 | xargs -0 COMMAND
# Requires nonstandard extensions to find and to shell (bash works).
# variables might not stay set once the loop ends:
find . -print0 | while IFS="" read -r -d "" file ; do ...
COMMAND "$file" # Use quoted "$file", not $file, everywhere.
done
# Requires nonstandard extensions to find and to shell (bash works).
# Underlying system must include named pipes (FIFOs)
#+ or the /dev/fd mechanism.
# In this version, variables *do* stay set after the loop ends,
# and you can read from stdin.
#+ (Change the 4 to another number if fd 4 is needed.)
while IFS="" read -r -d "" file <&4 ; do
COMMAND "$file" # Use quoted "$file" -- not $file, everywhere.
done 4< <(find . -print0)
# Named pipe version.
# Requires nonstandard extensions to find and to shell's read (bash ok).
# Underlying system must include named pipes (FIFOs).
# Again, in this version, variables *do* stay set after the loop ends,
# and you can read from stdin.
# (Change the 4 to something else if fd 4 needed).
mkfifo mypipe
find . -print0 &gt; mypipe &
while IFS="" read -r -d "" file <&4 ; do
COMMAND "$file" # Use quoted "$file", not $file, everywhere.
done 4< mypipe</pre>]
stringZ=abcABC123ABCabc
echo ${#stringZ} # 15
echo `expr length $stringZ` # 15
echo `expr "$stringZ" : '.*'` # 15
#!/bin/bash
# paragraph-space.sh
# Ver. 2.1, Reldate 29Jul12 [fixup]
# Inserts a blank line between paragraphs of a single-spaced text file.
# Usage: $0 <FILENAME
MINLEN=60 # Change this value? It's a judgment call.
# Assume lines shorter than $MINLEN characters ending in a period
#+ terminate a paragraph. See exercises below.
while read line # For as many lines as the input file has ...
do
echo "$line" # Output the line itself.
len=${#line}
if [[ "$len" -lt "$MINLEN" && "$line" =~ [*{\.}]$ ]]
# if [[ "$len" -lt "$MINLEN" && "$line" =~ \[*\.\] ]]
# An update to Bash broke the previous version of this script. Ouch!
# Thank you, Halim Srama, for pointing this out and suggesting a fix.
then echo # Add a blank line immediately
fi #+ after a short line terminated by a period.
done
exit
# Exercises:
# ---------
# 1) The script usually inserts a blank line at the end
#+ of the target file. Fix this.
# 2) Line 17 only considers periods as sentence terminators.
# Modify this to include other common end-of-sentence characters,
#+ such as ?, !, and ".
stringZ=abcABC123ABCabc
# |------|
# 12345678
echo `expr match "$stringZ" 'abc[A-Z]*.2'` # 8
echo `expr "$stringZ" : 'abc[A-Z]*.2'` # 8
stringZ=abcABC123ABCabc
# 123456 ...
echo `expr index "$stringZ" C12` # 6
# C position.
echo `expr index "$stringZ" 1c` # 3
# 'c' (in #3 position) matches before '1'.
stringZ=abcABC123ABCabc
# 0123456789.....
# 0-based indexing.
echo ${stringZ:0} # abcABC123ABCabc
echo ${stringZ:1} # bcABC123ABCabc
echo ${stringZ:7} # 23ABCabc
echo ${stringZ:7:3} # 23A
# Three characters of substring.
# Is it possible to index from the right end of the string?
echo ${stringZ:-4} # abcABC123ABCabc
# Defaults to full string, as in ${parameter:-default}.
# However . . .
echo ${stringZ:(-4)} # Cabc
echo ${stringZ: -4} # Cabc
# Now, it works.
# Parentheses or added space "escape" the position parameter.
# Thank you, Dan Jacobson, for pointing this out.
#!/bin/bash
# rand-string.sh
# Generating an 8-character "random" string.
if [ -n "$1" ] # If command-line argument present,
then #+ then set start-string to it.
str0="$1"
else # Else use PID of script as start-string.
str0="$$"
fi
POS=2 # Starting from position 2 in the string.
LEN=8 # Extract eight characters.
str1=$( echo "$str0" | md5sum | md5sum )
# Doubly scramble ^^^^^^ ^^^^^^
#+ by piping and repiping to md5sum.
randstring="${str1:$POS:$LEN}"
# Can parameterize ^^^^ ^^^^
echo "$randstring"
exit $?
# bozo$ ./rand-string.sh my-password
# 1bdd88c4
# No, this is is not recommended
#+ as a method of generating hack-proof passwords.
echo ${*:2} # Echoes second and following positional parameters.
echo ${@:2} # Same as above.
echo ${*:2:3} # Echoes three positional parameters, starting at second.
stringZ=abcABC123ABCabc
# 123456789......
# 1-based indexing.
echo `expr substr $stringZ 1 2` # ab
echo `expr substr $stringZ 4 3` # ABC
stringZ=abcABC123ABCabc
# =======
echo `expr match "$stringZ" '\(.[b-c]*[A-Z]..[0-9]\)'` # abcABC1
echo `expr "$stringZ" : '\(.[b-c]*[A-Z]..[0-9]\)'` # abcABC1
echo `expr "$stringZ" : '\(.......\)'` # abcABC1
# All of the above forms give an identical result.
stringZ=abcABC123ABCabc
# ======
echo `expr match "$stringZ" '.*\([A-C][A-C][A-C][a-c]*\)'` # ABCabc
echo `expr "$stringZ" : '.*\(......\)'` # ABCabc
stringZ=abcABC123ABCabc
# |----| shortest
# |----------| longest
echo ${stringZ#a*C} # 123ABCabc
# Strip out shortest match between 'a' and 'C'.
echo ${stringZ##a*C} # abc
# Strip out longest match between 'a' and 'C'.
# You can parameterize the substrings.
X='a*C'
echo ${stringZ#$X} # 123ABCabc
echo ${stringZ##$X} # abc
# As above.
# Rename all filenames in $PWD with "TXT" suffix to a "txt" suffix.
# For example, "file1.TXT" becomes "file1.txt" . . .
SUFF=TXT
suff=txt
for i in $(ls *.$SUFF)
do
mv -f $i ${i%.$SUFF}.$suff
# Leave unchanged everything *except* the shortest pattern match
#+ starting from the right-hand-side of the variable $i . . .
done ### This could be condensed into a "one-liner" if desired.
# Thank you, Rory Winston.
stringZ=abcABC123ABCabc
# || shortest
# |------------| longest
echo ${stringZ%b*c} # abcABC123ABCa
# Strip out shortest match between 'b' and 'c', from back of $stringZ.
echo ${stringZ%%b*c} # a
# Strip out longest match between 'b' and 'c', from back of $stringZ.
#!/bin/bash
# cvt.sh:
# Converts all the MacPaint image files in a directory to "pbm" format.
# Uses the "macptopbm" binary from the "netpbm" package,
#+ which is maintained by Brian Henderson (bryanh@giraffe-data.com).
# Netpbm is a standard part of most Linux distros.
OPERATION=macptopbm
SUFFIX=pbm # New filename suffix.
if [ -n "$1" ]
then
directory=$1 # If directory name given as a script argument...
else
directory=$PWD # Otherwise use current working directory.
fi
# Assumes all files in the target directory are MacPaint image files,
#+ with a ".mac" filename suffix.
for file in $directory/* # Filename globbing.
do
filename=${file%.*c} # Strip ".mac" suffix off filename
#+ ('.*c' matches everything
#+ between '.' and 'c', inclusive).
$OPERATION $file &gt; "$filename.$SUFFIX"
# Redirect conversion to new filename.
rm -f $file # Delete original files after converting.
echo "$filename.$SUFFIX" # Log what is happening to stdout.
done
exit 0
# Exercise:
# --------
# As it stands, this script converts *all* the files in the current
#+ working directory.
# Modify it to work *only* on files with a ".mac" suffix.
# *** And here's another way to do it. *** #
#!/bin/bash
# Batch convert into different graphic formats.
# Assumes imagemagick installed (standard in most Linux distros).
INFMT=png # Can be tif, jpg, gif, etc.
OUTFMT=pdf # Can be tif, jpg, gif, pdf, etc.
for pic in *"$INFMT"
do
p2=$(ls "$pic" | sed -e s/\.$INFMT//)
# echo $p2
convert "$pic" $p2.$OUTFMT
done
exit $?
#!/bin/bash
# ra2ogg.sh: Convert streaming audio files (*.ra) to ogg.
# Uses the "mplayer" media player program:
# http://www.mplayerhq.hu/homepage
# Uses the "ogg" library and "oggenc":
# http://www.xiph.org/
#
# This script may need appropriate codecs installed, such as sipr.so ...
# Possibly also the compat-libstdc++ package.
OFILEPREF=${1%%ra} # Strip off the "ra" suffix.
OFILESUFF=wav # Suffix for wav file.
OUTFILE="$OFILEPREF""$OFILESUFF"
E_NOARGS=85
if [ -z "$1" ] # Must specify a filename to convert.
then
echo "Usage: `basename $0` [filename]"
exit $E_NOARGS
fi
##########################################################################
mplayer "$1" -ao pcm:file=$OUTFILE
oggenc "$OUTFILE" # Correct file extension automatically added by oggenc.
##########################################################################
rm "$OUTFILE" # Delete intermediate *.wav file.
# If you want to keep it, comment out above line.
exit $?
# Note:
# ----
# On a Website, simply clicking on a *.ram streaming audio file
#+ usually only downloads the URL of the actual *.ra audio file.
# You can then use "wget" or something similar
#+ to download the *.ra file itself.
# Exercises:
# ---------
# As is, this script converts only *.ra filenames.
# Add flexibility by permitting use of *.ram and other filenames.
#
# If you're really ambitious, expand the script
#+ to do automatic downloads and conversions of streaming audio files.
# Given a URL, batch download streaming audio files (using "wget")
#+ and convert them on the fly.
#!/bin/bash
# getopt-simple.sh
# Author: Chris Morgan
# Used in the ABS Guide with permission.
getopt_simple()
{
echo "getopt_simple()"
echo "Parameters are '$*'"
until [ -z "$1" ]
do
echo "Processing parameter of: '$1'"
if [ ${1:0:1} = '/' ]
then
tmp=${1:1} # Strip off leading '/' . . .
parameter=${tmp%%=*} # Extract name.
value=${tmp##*=} # Extract value.
echo "Parameter: '$parameter', value: '$value'"
eval $parameter=$value
fi
shift
done
}
# Pass all options to getopt_simple().
getopt_simple $*
echo "test is '$test'"
echo "test2 is '$test2'"
exit 0 # See also, UseGetOpt.sh, a modified version of this script.
---
sh getopt_example.sh /test=value1 /test2=value2
Parameters are '/test=value1 /test2=value2'
Processing parameter of: '/test=value1'
Parameter: 'test', value: 'value1'
Processing parameter of: '/test2=value2'
Parameter: 'test2', value: 'value2'
test is 'value1'
test2 is 'value2'
stringZ=abcABC123ABCabc
echo ${stringZ/abc/xyz} # xyzABC123ABCabc
# Replaces first match of 'abc' with 'xyz'.
echo ${stringZ//abc/xyz} # xyzABC123ABCxyz
# Replaces all matches of 'abc' with # 'xyz'.
echo ---------------
echo "$stringZ" # abcABC123ABCabc
echo ---------------
# The string itself is not altered!
# Can the match and replacement strings be parameterized?
match=abc
repl=000
echo ${stringZ/$match/$repl} # 000ABC123ABCabc
# ^ ^ ^^^
echo ${stringZ//$match/$repl} # 000ABC123ABC000
# Yes! ^ ^ ^^^ ^^^
echo
# What happens if no $replacement string is supplied?
echo ${stringZ/abc} # ABC123ABCabc
echo ${stringZ//abc} # ABC123ABC
# A simple deletion takes place.
stringZ=abcABC123ABCabc
echo ${stringZ/#abc/XYZ} # XYZABC123ABCabc
# Replaces front-end match of 'abc' with 'XYZ'.
echo ${stringZ/%abc/XYZ} # abcABC123ABCXYZ
# Replaces back-end match of 'abc' with 'XYZ'.
#!/bin/bash
# substring-extraction.sh
String=23skidoo1
# 012345678 Bash
# 123456789 awk
# Note different string indexing system:
# Bash numbers first character of string as 0.
# Awk numbers first character of string as 1.
echo ${String:2:4} # position 3 (0-1-2), 4 characters long
# skid
# The awk equivalent of ${string:pos:length} is substr(string,pos,length).
echo | awk '
{ print substr("'"${String}"'",3,4) # skid
}
'
# Piping an empty "echo" to awk gives it dummy input,
#+ and thus makes it unnecessary to supply a filename.
echo "----"
# And likewise:
echo | awk '
{ print index("'"${String}"'", "skid") # 3
} # (skid starts at position 3)
' # The awk equivalent of "expr index" ...
exit 0</pre>]
[]
for arg in "$var1" "$var2" "$var3" ... "$varN"
# In pass 1 of the loop, arg = $var1
# In pass 2 of the loop, arg = $var2
# In pass 3 of the loop, arg = $var3
# ...
# In pass N of the loop, arg = $varN
# Arguments in [list] quoted to prevent possible word splitting.
#!/bin/bash
# Listing the planets.
for planet in Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
do
echo $planet # Each planet on a separate line.
done
echo; echo
for planet in "Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto"
# All planets on same line.
# Entire 'list' enclosed in quotes creates a single variable.
# Why? Whitespace incorporated into the variable.
do
echo $planet
done
echo; echo "Whoops! Pluto is no longer a planet!"
exit 0
#!/bin/bash
# Planets revisited.
# Associate the name of each planet with its distance from the sun.
for planet in "Mercury 36" "Venus 67" "Earth 93" "Mars 142" "Jupiter 483"
do
set -- $planet # Parses variable "planet"
#+ and sets positional parameters.
# The "--" prevents nasty surprises if $planet is null or
#+ begins with a dash.
# May need to save original positional parameters,
#+ since they get overwritten.
# One way of doing this is to use an array,
# original_params=("$@")
echo "$1 $2,000,000 miles from the sun"
#-------two tabs---concatenate zeroes onto parameter $2
done
# (Thanks, S.C., for additional clarification.)
exit 0
#!/bin/bash
# fileinfo.sh
FILES="/usr/sbin/accept
/usr/sbin/pwck
/usr/sbin/chroot
/usr/bin/fakefile
/sbin/badblocks
/sbin/ypbind" # List of files you are curious about.
# Threw in a dummy file, /usr/bin/fakefile.
echo
for file in $FILES
do
if [ ! -e "$file" ] # Check if file exists.
then
echo "$file does not exist."; echo
continue # On to next.
fi
ls -l $file | awk '{ print $8 " file size: " $5 }' # Print 2 fields.
whatis `basename $file` # File info.
# Note that the whatis database needs to have been set up for this to work.
# To do this, as root run /usr/bin/makewhatis.
echo
done
exit 0
#!/bin/bash
filename="*txt"
for file in $filename
do
echo "Contents of $file"
echo "---"
cat "$file"
echo
done
#!/bin/bash
# list-glob.sh: Generating [list] in a for-loop, using "globbing" ...
# Globbing = filename expansion.
echo
for file in *
# ^ Bash performs filename expansion
#+ on expressions that globbing recognizes.
do
ls -l "$file" # Lists all files in $PWD (current directory).
# Recall that the wild card character "*" matches every filename,
#+ however, in "globbing," it doesn't match dot-files.
# If the pattern matches no file, it is expanded to itself.
# To prevent this, set the nullglob option
#+ (shopt -s nullglob).
# Thanks, S.C.
done
echo; echo
for file in [jx]*
do
rm -f $file # Removes only files beginning with "j" or "x" in $PWD.
echo "Removed file \"$file\"".
done
echo
exit 0
#!/bin/bash
# Invoke this script both with and without arguments,
#+ and see what happens.
for a
do
echo -n "$a "
done
# The 'in list' missing, therefore the loop operates on '$@'
#+ (command-line argument list, including whitespace).
echo
exit 0
#!/bin/bash
# for-loopcmd.sh: for-loop with [list]
#+ generated by command substitution.
NUMBERS="9 7 3 8 37.53"
for number in `echo $NUMBERS` # for number in 9 7 3 8 37.53
do
echo -n "$number "
done
echo
exit 0
#!/bin/bash
# bin-grep.sh: Locates matching strings in a binary file.
# A "grep" replacement for binary files.
# Similar effect to "grep -a"
E_BADARGS=65
E_NOFILE=66
if [ $# -ne 2 ]
then
echo "Usage: `basename $0` search_string filename"
exit $E_BADARGS
fi
if [ ! -f "$2" ]
then
echo "File \"$2\" does not exist."
exit $E_NOFILE
fi
IFS=$'\012' # Per suggestion of Anton Filippov.
# was: IFS="\n"
for word in $( strings "$2" | grep "$1" )
# The "strings" command lists strings in binary files.
# Output then piped to "grep", which tests for desired string.
do
echo $word
done
# As S.C. points out, lines 23 - 30 could be replaced with the simpler
# strings "$2" | grep "$1" | tr -s "$IFS" '[\n*]'
# Try something like "./bin-grep.sh mem /bin/ls"
#+ to exercise this script.
exit 0
#!/bin/bash
# userlist.sh
PASSWORD_FILE=/etc/passwd
n=1 # User number
for name in $(awk 'BEGIN{FS=":"}{print $1}' < "$PASSWORD_FILE" )
# Field separator = : ^^^^^^
# Print first field ^^^^^^^^
# Get input from password file /etc/passwd ^^^^^^^^^^^^^^^^^
do
echo "USER #$n = $name"
let "n += 1"
done
# USER #1 = root
# USER #2 = bin
# USER #3 = daemon
# ...
# USER #33 = bozo
exit $?
# Discussion:
# ----------
# How is it that an ordinary user, or a script run by same,
#+ can read /etc/passwd? (Hint: Check the /etc/passwd file permissions.)
# Is this a security hole? Why or why not?
#!/bin/bash
# findstring.sh:
# Find a particular string in the binaries in a specified directory.
directory=/usr/bin/
fstring="Free Software Foundation" # See which files come from the FSF.
for file in $( find $directory -type f -name '*' | sort )
do
strings -f $file | grep "$fstring" | sed -e "s%$directory%%"
# In the "sed" expression,
#+ it is necessary to substitute for the normal "/" delimiter
#+ because "/" happens to be one of the characters filtered out.
# Failure to do so gives an error message. (Try it.)
done
exit $?
# Exercise (easy):
# ---------------
# Convert this script to take command-line parameters
#+ for $directory and $fstring.
generate_list ()
{
echo "one two three"
}
for word in $(generate_list) # Let "word" grab output of function.
do
echo "$word"
done
# one
# two
# three
#!/bin/bash
# symlinks.sh: Lists symbolic links in a directory.
directory=${1-`pwd`}
# Defaults to current working directory,
#+ if not otherwise specified.
# Equivalent to code block below.
# ----------------------------------------------------------
# ARGS=1 # Expect one command-line argument.
#
# if [ $# -ne "$ARGS" ] # If not 1 arg...
# then
# directory=`pwd` # current working directory
# else
# directory=$1
# fi
# ----------------------------------------------------------
echo "symbolic links in directory \"$directory\""
for file in "$( find $directory -type l )" # -type l = symbolic links
do
echo "$file"
done | sort # Otherwise file list is unsorted.
# Strictly speaking, a loop isn't really necessary here,
#+ since the output of the "find" command is expanded into a single word.
# However, it's easy to understand and illustrative this way.
# As Dominik 'Aeneas' Schnitzer points out,
#+ failing to quote $( find $directory -type l )
#+ will choke on filenames with embedded whitespace.
# containing whitespace.
exit 0
# --------------------------------------------------------
# Jean Helou proposes the following alternative:
echo "symbolic links in directory \"$directory\""
# Backup of the current IFS. One can never be too cautious.
OLDIFS=$IFS
IFS=:
for file in $(find $directory -type l -printf "%p$IFS")
do # ^^^^^^^^^^^^^^^^
echo "$file"
done|sort
# And, James "Mike" Conley suggests modifying Helou's code thusly:
OLDIFS=$IFS
IFS='' # Null IFS means no word breaks
for file in $( find $directory -type l )
do
echo $file
done | sort
# This works in the "pathological" case of a directory name having
#+ an embedded colon.
# "This also fixes the pathological case of the directory name having
#+ a colon (or space in earlier example) as well."
#!/bin/bash
# symlinks.sh: Lists symbolic links in a directory.
OUTFILE=symlinks.list # save-file
directory=${1-`pwd`}
# Defaults to current working directory,
#+ if not otherwise specified.
echo "symbolic links in directory \"$directory\"" &gt; "$OUTFILE"
echo "---------------------------" &gt;&gt; "$OUTFILE"
for file in "$( find $directory -type l )" # -type l = symbolic links
do
echo "$file"
done | sort &gt;&gt; "$OUTFILE" # stdout of loop
# ^^^^^^^^^^^^^ redirected to save file.
# echo "Output file = $OUTFILE"
exit $?
#!/bin/bash
# Multiple ways to count up to 10.
echo
# Standard syntax.
for a in 1 2 3 4 5 6 7 8 9 10
do
echo -n "$a "
done
echo; echo
# +==========================================+
# Using "seq" ...
for a in `seq 10`
do
echo -n "$a "
done
echo; echo
# +==========================================+
# Using brace expansion ...
# Bash, version 3+.
for a in {1..10}
do
echo -n "$a "
done
echo; echo
# +==========================================+
# Now, let's do the same, using C-like syntax.
LIMIT=10
for ((a=1; a <= LIMIT ; a++)) # Double parentheses, and naked "LIMIT"
do
echo -n "$a "
done # A construct borrowed from ksh93.
echo; echo
# +=========================================================================+
# Let's use the C "comma operator" to increment two variables simultaneously.
for ((a=1, b=1; a <= LIMIT ; a++, b++))
do # The comma concatenates operations.
echo -n "$a-$b "
done
echo; echo
exit 0
#!/bin/bash
# Faxing (must have 'efax' package installed).
EXPECTED_ARGS=2
E_BADARGS=85
MODEM_PORT="/dev/ttyS2" # May be different on your machine.
# ^^^^^ PCMCIA modem card default port.
if [ $# -ne $EXPECTED_ARGS ]
# Check for proper number of command-line args.
then
echo "Usage: `basename $0` phone# text-file"
exit $E_BADARGS
fi
if [ ! -f "$2" ]
then
echo "File $2 is not a text file."
# File is not a regular file, or does not exist.
exit $E_BADARGS
fi
fax make $2 # Create fax-formatted files from text files.
for file in $(ls $2.0*) # Concatenate the converted files.
# Uses wild card (filename "globbing")
#+ in variable list.
do
fil="$fil $file"
done
efax -d "$MODEM_PORT" -t "T$1" $fil # Finally, do the work.
# Trying adding -o1 if above line fails.
# As S.C. points out, the for-loop can be eliminated with
# efax -d /dev/ttyS2 -o1 -t "T$1" $2.0*
#+ but it's not quite as instructive [grin].
exit $? # Also, efax sends diagnostic messages to stdout.
for((n=1; n<=10; n++))
# No do!
{
echo -n "* $n *"
}
# No done!
# Outputs:
# * 1 ** 2 ** 3 ** 4 ** 5 ** 6 ** 7 ** 8 ** 9 ** 10 *
# And, echo $? returns 0, so Bash does not register an error.
echo
# But, note that in a classic for-loop: for n in [list] ...
#+ a terminal semicolon is required.
for n in 1 2 3
{ echo -n "$n "; }
# ^
# Thank you, YongYe, for pointing this out.
#!/bin/bash
var0=0
LIMIT=10
while [ "$var0" -lt "$LIMIT" ]
# ^ ^
# Spaces, because these are "test-brackets" . . .
do
echo -n "$var0 " # -n suppresses newline.
# ^ Space, to separate printed out numbers.
var0=`expr $var0 + 1` # var0=$(($var0+1)) also works.
# var0=$((var0 + 1)) also works.
# let "var0 += 1" also works.
done # Various other methods also work.
echo
exit 0
#!/bin/bash
echo
# Equivalent to:
while [ "$var1" != "end" ] # while test "$var1" != "end"
do
echo "Input variable #1 (end to exit) "
read var1 # Not 'read $var1' (why?).
echo "variable #1 = $var1" # Need quotes because of "#" . . .
# If input is 'end', echoes it here.
# Does not test for termination condition until top of loop.
echo
done
exit 0
#!/bin/bash
var1=unset
previous=$var1
while echo "previous-variable = $previous"
echo
previous=$var1
[ "$var1" != end ] # Keeps track of what $var1 was previously.
# Four conditions on *while*, but only the final one controls loop.
# The *last* exit status is the one that counts.
do
echo "Input variable #1 (end to exit) "
read var1
echo "variable #1 = $var1"
done
# Try to figure out how this all works.
# It's a wee bit tricky.
exit 0
#!/bin/bash
# wh-loopc.sh: Count to 10 in a "while" loop.
LIMIT=10 # 10 iterations.
a=1
while [ "$a" -le $LIMIT ]
do
echo -n "$a "
let "a+=1"
done # No surprises, so far.
echo; echo
# +=================================================================+
# Now, we'll repeat with C-like syntax.
((a = 1)) # a=1
# Double parentheses permit space when setting a variable, as in C.
while (( a <= LIMIT )) # Double parentheses,
do #+ and no "$" preceding variables.
echo -n "$a "
((a += 1)) # let "a+=1"
# Yes, indeed.
# Double parentheses permit incrementing a variable with C-like syntax.
done
echo
# C and Java programmers can feel right at home in Bash.
exit 0
t=0
condition ()
{
((t++))
if [ $t -lt 5 ]
then
return 0 # true
else
return 1 # false
fi
}
while condition
# ^^^^^^^^^
# Function call -- four loop iterations.
do
echo "Still going: t = $t"
done
# Still going: t = 1
# Still going: t = 2
# Still going: t = 3
# Still going: t = 4
while condition
do
command(s) ...
done
cat $filename | # Supply input from a file.
while read line # As long as there is another line to read ...
do
...
done
# =========== Snippet from "sd.sh" example script ========== #
while read value # Read one data point at a time.
do
rt=$(echo "scale=$SC; $rt + $value" | bc)
(( ct++ ))
done
am=$(echo "scale=$SC; $rt / $ct" | bc)
echo $am; return $ct # This function "returns" TWO values!
# Caution: This little trick will not work if $ct &gt; 255!
# To handle a larger number of data points,
#+ simply comment out the "return $ct" above.
} <"$datafile" # Feed in data file.
#!/bin/bash
END_CONDITION=end
until [ "$var1" = "$END_CONDITION" ]
# Tests condition here, at top of loop.
do
echo "Input variable #1 "
echo "($END_CONDITION to exit)"
read var1
echo "variable #1 = $var1"
echo
done
# --- #
# As with "for" and "while" loops,
#+ an "until" loop permits C-like test constructs.
LIMIT=10
var=0
until (( var &gt; LIMIT ))
do # ^^ ^ ^ ^^ No brackets, no $ prefixing variables.
echo -n "$var "
(( var++ ))
done # 0 1 2 3 4 5 6 7 8 9 10
exit 0</pre>]
[]
# $1 is field #1, $2 is field #2, etc.
echo one two | awk '{print $1}'
# one
echo one two | awk '{print $2}'
# two
# But what is field #0 ($0)?
echo one two | awk '{print $0}'
# one two
# All the fields!
awk '{print $3}' $filename
# Prints field #3 of file $filename to stdout.
awk '{print $1 $5 $6}' $filename
# Prints fields #1, #5, and #6 of file $filename.
awk '{print $0}' $filename
# Prints the entire file!
# Same effect as: cat $filename . . . or . . . sed '' $filename
{ total += ${column_number} }
END { print total }
#! /bin/sh
# letter-count2.sh: Counting letter occurrences in a text file.
#
# Script by nyal [nyal@voila.fr].
# Used in ABS Guide with permission.
# Recommented and reformatted by ABS Guide author.
# Version 1.1: Modified to work with gawk 3.1.3.
# (Will still work with earlier versions.)
INIT_TAB_AWK=""
# Parameter to initialize awk script.
count_case=0
FILE_PARSE=$1
E_PARAMERR=85
usage()
{
echo "Usage: letter-count.sh file letters" 2&gt;&1
# For example: ./letter-count2.sh filename.txt a b c
exit $E_PARAMERR # Too few arguments passed to script.
}
if [ ! -f "$1" ] ; then
echo "$1: No such file." 2&gt;&1
usage # Print usage message and exit.
fi
if [ -z "$2" ] ; then
echo "$2: No letters specified." 2&gt;&1
usage
fi
shift # Letters specified.
for letter in `echo $@` # For each one . . .
do
INIT_TAB_AWK="$INIT_TAB_AWK tab_search[${count_case}] = \
\"$letter\"; final_tab[${count_case}] = 0; "
# Pass as parameter to awk script below.
count_case=`expr $count_case + 1`
done
# DEBUG:
# echo $INIT_TAB_AWK;
cat $FILE_PARSE |
# Pipe the target file to the following awk script.
# ---------------------------------------------------------------------
# Earlier version of script:
# awk -v tab_search=0 -v final_tab=0 -v tab=0 -v \
# nb_letter=0 -v chara=0 -v chara2=0 \
awk \
"BEGIN { $INIT_TAB_AWK } \
{ split(\$0, tab, \"\"); \
for (chara in tab) \
{ for (chara2 in tab_search) \
{ if (tab_search[chara2] == tab[chara]) { final_tab[chara2]++ } } } } \
END { for (chara in final_tab) \
{ print tab_search[chara] \" =&gt; \" final_tab[chara] } }"
# ---------------------------------------------------------------------
# Nothing all that complicated, just . . .
#+ for-loops, if-tests, and a couple of specialized functions.
exit $?
# Compare this script to letter-count.sh.</pre>]
command-1 && command-2 && command-3 && ... command-n
equation()
{ # core algorithm used for doubling and halving the coordinates
[[ ${cdx} ]] && ((y=cy+(ccy-cdy)${2}2))
eval ${1}+=\"${x} ${y} \"
}
#!/bin/bash
# and list
if [ ! -z "$1" ] && echo "Argument #1 = $1" && [ ! -z "$2" ] && \
# ^^ ^^ ^^
echo "Argument #2 = $2"
then
echo "At least 2 arguments passed to script."
# All the chained commands return true.
else
echo "Fewer than 2 arguments passed to script."
# At least one of the chained commands returns false.
fi
# Note that "if [ ! -z $1 ]" works, but its alleged equivalent,
# "if [ -n $1 ]" does not.
# However, quoting fixes this.
# if "[ -n "$1" ]" works.
# ^ ^ Careful!
# It is always best to QUOTE the variables being tested.
# This accomplishes the same thing, using "pure" if/then statements.
if [ ! -z "$1" ]
then
echo "Argument #1 = $1"
fi
if [ ! -z "$2" ]
then
echo "Argument #2 = $2"
echo "At least 2 arguments passed to script."
else
echo "Fewer than 2 arguments passed to script."
fi
# It's longer and more ponderous than using an "and list".
exit $?
#!/bin/bash
ARGS=1 # Number of arguments expected.
E_BADARGS=85 # Exit value if incorrect number of args passed.
test $# -ne $ARGS && \
# ^^^^^^^^^^^^ condition #1
echo "Usage: `basename $0` $ARGS argument(s)" && exit $E_BADARGS
# ^^
# If condition #1 tests true (wrong number of args passed to script),
#+ then the rest of the line executes, and script terminates.
# Line below executes only if the above test fails.
echo "Correct number of arguments passed to this script."
exit 0
# To check exit value, do a "echo $?" after script termination.
arg1=$@ && [ -z "$arg1" ] && arg1=DEFAULT
# Set $arg1 to command-line arguments, if any.
# But . . . set to DEFAULT if not specified on command-line.
command-1 || command-2 || command-3 || ... command-n
#!/bin/bash
# delete.sh, a not-so-cunning file deletion utility.
# Usage: delete filename
E_BADARGS=85
if [ -z "$1" ]
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS # No arg? Bail out.
else
file=$1 # Set filename.
fi
[ ! -f "$file" ] && echo "File \"$file\" not found. \
Cowardly refusing to delete a nonexistent file."
# AND LIST, to give error message if file not present.
# Note echo message continuing on to a second line after an escape.
[ ! -f "$file" ] || (rm -f $file; echo "File \"$file\" deleted.")
# OR LIST, to delete file if present.
# Note logic inversion above.
# AND LIST executes on true, OR LIST on false.
exit $?
# ==&gt; The following snippets from the /etc/rc.d/init.d/single
#+==&gt; script by Miquel van Smoorenburg
#+==&gt; illustrate use of "and" and "or" lists.
# ==&gt; "Arrowed" comments added by document author.
[ -x /usr/bin/clear ] && /usr/bin/clear
# ==&gt; If /usr/bin/clear exists, then invoke it.
# ==&gt; Checking for the existence of a command before calling it
#+==&gt; avoids error messages and other awkward consequences.
# ==&gt; . . .
# If they want to run something in single user mode, might as well run it...
for i in /etc/rc1.d/S[0-9][0-9]* ; do
# Check if the script is there.
[ -x "$i" ] || continue
# ==&gt; If corresponding file in $PWD *not* found,
#+==&gt; then "continue" by jumping to the top of the loop.
# Reject backup files and files generated by rpm.
case "$1" in
*.rpmsave|*.rpmorig|*.rpmnew|*~|*.orig)
continue;;
esac
[ "$i" = "/etc/rc1.d/S00single" ] && continue
# ==&gt; Set script name, but don't execute it yet.
$i start
done
# ==&gt; . . .
false && true || echo false # false
# Same result as
( false && true ) || echo false # false
# But NOT
false && ( true || echo false ) # (nothing echoed)
# Note left-to-right grouping and evaluation of statements.
# It's usually best to avoid such complexities.
# Thanks, S.C.</pre>]
[]
[]
#!/bin/bash
# localized.sh
# Script by Stéphane Chazelas,
#+ modified by Bruno Haible, bugfixed by Alfredo Pironti.
. gettext.sh
E_CDERROR=65
error()
{
printf "$@" &gt;&2
exit $E_CDERROR
}
cd $var || error "`eval_gettext \"Can\'t cd to \\\$var.\"`"
# The triple backslashes (escapes) in front of $var needed
#+ "because eval_gettext expects a string
#+ where the variable values have not yet been substituted."
# -- per Bruno Haible
read -p "`gettext \"Enter the value: \"`" var
# ...
# ------------------------------------------------------------------
# Alfredo Pironti comments:
# This script has been modified to not use the $"..." syntax in
#+ favor of the "`gettext \"...\"`" syntax.
# This is ok, but with the new localized.sh program, the commands
#+ "bash -D filename" and "bash --dump-po-string filename"
#+ will produce no output
#+ (because those command are only searching for the $"..." strings)!
# The ONLY way to extract strings from the new file is to use the
# 'xgettext' program. However, the xgettext program is buggy.
# Note that 'xgettext' has another bug.
#
# The shell fragment:
# gettext -s "I like Bash"
# will be correctly extracted, but . . .
# xgettext -s "I like Bash"
# . . . fails!
# 'xgettext' will extract "-s" because
#+ the command only extracts the
#+ very first argument after the 'gettext' word.
# Escape characters:
#
# To localize a sentence like
# echo -e "Hello\tworld!"
#+ you must use
# echo -e "`gettext \"Hello\\tworld\"`"
# The "double escape character" before the `t' is needed because
#+ 'gettext' will search for a string like: 'Hello\tworld'
# This is because gettext will read one literal `\')
#+ and will output a string like "Bonjour\tmonde",
#+ so the 'echo' command will display the message correctly.
#
# You may not use
# echo "`gettext -e \"Hello\tworld\"`"
#+ due to the xgettext bug explained above.
# Let's localize the following shell fragment:
# echo "-h display help and exit"
#
# First, one could do this:
# echo "`gettext \"-h display help and exit\"`"
# This way 'xgettext' will work ok,
#+ but the 'gettext' program will read "-h" as an option!
#
# One solution could be
# echo "`gettext -- \"-h display help and exit\"`"
# This way 'gettext' will work,
#+ but 'xgettext' will extract "--", as referred to above.
#
# The workaround you may use to get this string localized is
# echo -e "`gettext \"\\0-h display help and exit\"`"
# We have added a \0 (NULL) at the beginning of the sentence.
# This way 'gettext' works correctly, as does 'xgettext.'
# Moreover, the NULL character won't change the behavior
#+ of the 'echo' command.
# ------------------------------------------------------------------
#: a:6
msgid "Can't cd to $var."
msgstr "Impossible de se positionner dans le repertoire $var."
#: a:7
msgid "Enter the value: "
msgstr "Entrez la valeur : "
# The string are dumped with the variable names, not with the %s syntax,
#+ similar to C programs.
#+ This is a very cool feature if the programmer uses
#+ variable names that make sense!
TEXTDOMAINDIR=/usr/local/share/locale
TEXTDOMAIN=localized.sh
#!/bin/bash
# localized.sh
E_CDERROR=65
error() {
local format=$1
shift
printf "$(gettext -s "$format")" "$@" &gt;&2
exit $E_CDERROR
}
cd $var || error "Can't cd to %s." "$var"
read -p "$(gettext -s "Enter the value: ")" var
# ...</pre>]
#!/bin/bash
# Using "seq"
echo
for a in `seq 80` # or for a in $( seq 80 )
# Same as for a in 1 2 3 4 5 ... 80 (saves much typing!).
# May also use 'jot' (if present on system).
do
echo -n "$a "
done # 1 2 3 4 5 ... 80
# Example of using the output of a command to generate
# the [list] in a "for" loop.
echo; echo
COUNT=80 # Yes, 'seq' also accepts a replaceable parameter.
for a in `seq $COUNT` # or for a in $( seq $COUNT )
do
echo -n "$a "
done # 1 2 3 4 5 ... 80
echo; echo
BEGIN=75
END=80
for a in `seq $BEGIN $END`
# Giving "seq" two arguments starts the count at the first one,
#+ and continues until it reaches the second.
do
echo -n "$a "
done # 75 76 77 78 79 80
echo; echo
BEGIN=45
INTERVAL=5
END=80
for a in `seq $BEGIN $INTERVAL $END`
# Giving "seq" three arguments starts the count at the first one,
#+ uses the second for a step interval,
#+ and continues until it reaches the third.
do
echo -n "$a "
done # 45 50 55 60 65 70 75 80
echo; echo
exit 0
# Create a set of 10 files,
#+ named file.1, file.2 . . . file.10.
COUNT=10
PREFIX=file
for filename in `seq $COUNT`
do
touch $PREFIX.$filename
# Or, can do other operations,
#+ such as rm, grep, etc.
done
#!/bin/bash
# letter-count.sh: Counting letter occurrences in a text file.
# Written by Stefano Palmeri.
# Used in ABS Guide with permission.
# Slightly modified by document author.
MINARGS=2 # Script requires at least two arguments.
E_BADARGS=65
FILE=$1
let LETTERS=$#-1 # How many letters specified (as command-line args).
# (Subtract 1 from number of command-line args.)
show_help(){
echo
echo Usage: `basename $0` file letters
echo Note: `basename $0` arguments are case sensitive.
echo Example: `basename $0` foobar.txt G n U L i N U x.
echo
}
# Checks number of arguments.
if [ $# -lt $MINARGS ]; then
echo
echo "Not enough arguments."
echo
show_help
exit $E_BADARGS
fi
# Checks if file exists.
if [ ! -f $FILE ]; then
echo "File \"$FILE\" does not exist."
exit $E_BADARGS
fi
# Counts letter occurrences .
for n in `seq $LETTERS`; do
shift
if [[ `echo -n "$1" | wc -c` -eq 1 ]]; then # Checks arg.
echo "$1" -\&gt; `cat $FILE | tr -cd "$1" | wc -c` # Counting.
else
echo "$1 is not a single char."
fi
done
exit $?
# This script has exactly the same functionality as letter-count2.sh,
#+ but executes faster.
# Why?
#!/bin/bash
# Using getopt
# Try the following when invoking this script:
# sh ex33a.sh -a
# sh ex33a.sh -abc
# sh ex33a.sh -a -b -c
# sh ex33a.sh -d
# sh ex33a.sh -dXYZ
# sh ex33a.sh -d XYZ
# sh ex33a.sh -abcd
# sh ex33a.sh -abcdZ
# sh ex33a.sh -z
# sh ex33a.sh a
# Explain the results of each of the above.
E_OPTERR=65
if [ "$#" -eq 0 ]
then # Script needs at least one command-line argument.
echo "Usage $0 -[options a,b,c]"
exit $E_OPTERR
fi
set -- `getopt "abcd:" "$@"`
# Sets positional parameters to command-line arguments.
# What happens if you use "$*" instead of "$@"?
while [ ! -z "$1" ]
do
case "$1" in
-a) echo "Option \"a\"";;
-b) echo "Option \"b\"";;
-c) echo "Option \"c\"";;
-d) echo "Option \"d\" $2";;
*) break;;
esac
shift
done
# It is usually better to use the 'getopts' builtin in a script.
# See "ex33.sh."
exit 0
args=$(getopt -o a:bc:d -- "$@")
eval set -- "$args"
yes ()
{ # Trivial emulation of "yes" ...
local DEFAULT_TEXT="y"
while [ true ] # Endless loop.
do
if [ -z "$1" ]
then
echo "$DEFAULT_TEXT"
else # If argument ...
echo "$1" # ... expand and echo it.
fi
done # The only things missing are the
} #+ --help and --version options.
cat listfile* | sort | tee check.file | uniq &gt; result.file
# ^^^^^^^^^^^^^^ ^^^^
# The file "check.file" contains the concatenated sorted "listfiles,"
#+ before the duplicate lines are removed by 'uniq.'
#!/bin/bash
# This short script by Omair Eshkenazi.
# Used in ABS Guide with permission (thanks!).
mkfifo pipe1 # Yes, pipes can be given names.
mkfifo pipe2 # Hence the designation "named pipe."
(cut -d' ' -f1 | tr "a-z" "A-Z") &gt;pipe2 <pipe1 &
ls -l | tr -s ' ' | cut -d' ' -f3,9- | tee pipe1 |
cut -d' ' -f2 | paste - pipe2
rm -f pipe1
rm -f pipe2
# No need to kill background processes when script terminates (why not?).
exit $?
Now, invoke the script and explain the output:
sh mkfifo-example.sh
4830.tar.gz BOZO
pipe1 BOZO
pipe2 BOZO
mkfifo-example.sh BOZO
Mixed.msg BOZO
# Converting a file to all uppercase:
dd if=$filename conv=ucase &gt; $filename.uppercase
# lcase # For lower case conversion
#!/bin/bash
# self-copy.sh
# This script copies itself.
file_subscript=copy
dd if=$0 of=$0.$file_subscript 2&gt;/dev/null
# Suppress messages from dd: ^^^^^^^^^^^
exit $?
# A program whose only output is its own source code
#+ is called a "quine" per Willard Quine.
# Does this script qualify as a quine?
#!/bin/bash
# exercising-dd.sh
# Script by Stephane Chazelas.
# Somewhat modified by ABS Guide author.
infile=$0 # This script.
outfile=log.txt # Output file left behind.
n=8
p=11
dd if=$infile of=$outfile bs=1 skip=$((n-1)) count=$((p-n+1)) 2&gt; /dev/null
# Extracts characters n to p (8 to 11) from this script ("bash").
# ----------------------------------------------------------------
echo -n "hello vertical world" | dd cbs=1 conv=unblock 2&gt; /dev/null
# Echoes "hello vertical world" vertically downward.
# Why? A newline follows each character dd emits.
exit $?
#!/bin/bash
# dd-keypress.sh: Capture keystrokes without needing to press ENTER.
keypresses=4 # Number of keypresses to capture.
old_tty_setting=$(stty -g) # Save old terminal settings.
echo "Press $keypresses keys."
stty -icanon -echo # Disable canonical mode.
# Disable local echo.
keys=$(dd bs=1 count=$keypresses 2&gt; /dev/null)
# 'dd' uses stdin, if "if" (input file) not specified.
stty "$old_tty_setting" # Restore old terminal settings.
echo "You pressed the \"$keys\" keys."
# Thanks, Stephane Chazelas, for showing the way.
exit 0
echo -n . | dd bs=1 seek=4 of=file conv=notrunc
# The "conv=notrunc" option means that the output file
#+ will not be truncated.
# Thanks, S.C.
#!/bin/bash
# rp.sdcard.sh
# Preparing an SD card with a bootable image for the Raspberry Pi.
# $1 = imagefile name
# $2 = sdcard (device file)
# Otherwise defaults to the defaults, see below.
DEFAULTbs=4M # Block size, 4 mb default.
DEFAULTif="2013-07-26-wheezy-raspbian.img" # Commonly used distro.
DEFAULTsdcard="/dev/mmcblk0" # May be different. Check!
ROOTUSER_NAME=root # Must run as root!
E_NOTROOT=81
E_NOIMAGE=82
username=$(id -nu) # Who is running this script?
if [ "$username" != "$ROOTUSER_NAME" ]
then
echo "This script must run as root or with root privileges."
exit $E_NOTROOT
fi
if [ -n "$1" ]
then
imagefile="$1"
else
imagefile="$DEFAULTif"
fi
if [ -n "$2" ]
then
sdcard="$2"
else
sdcard="$DEFAULTsdcard"
fi
if [ ! -e $imagefile ]
then
echo "Image file \"$imagefile\" not found!"
exit $E_NOIMAGE
fi
echo "Last chance to change your mind!"; echo
read -s -n1 -p "Hit a key to write $imagefile to $sdcard [Ctl-c to exit]."
echo; echo
echo "Writing $imagefile to $sdcard ..."
dd bs=$DEFAULTbs if=$imagefile of=$sdcard
exit $?
# Exercises:
# ---------
# 1) Provide additional error checking.
# 2) Have script autodetect device file for SD card (difficult!).
# 3) Have script sutodetect image file (*img) in $PWD.
#!/bin/bash
# blot-out.sh: Erase "all" traces of a file.
# This script overwrites a target file alternately
#+ with random bytes, then zeros before finally deleting it.
# After that, even examining the raw disk sectors by conventional methods
#+ will not reveal the original file data.
PASSES=7 # Number of file-shredding passes.
# Increasing this slows script execution,
#+ especially on large target files.
BLOCKSIZE=1 # I/O with /dev/urandom requires unit block size,
#+ otherwise you get weird results.
E_BADARGS=70 # Various error exit codes.
E_NOT_FOUND=71
E_CHANGED_MIND=72
if [ -z "$1" ] # No filename specified.
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS
fi
file=$1
if [ ! -e "$file" ]
then
echo "File \"$file\" not found."
exit $E_NOT_FOUND
fi
echo; echo -n "Are you absolutely sure you want to blot out \"$file\" (y/n)? "
read answer
case "$answer" in
[nN]) echo "Changed your mind, huh?"
exit $E_CHANGED_MIND
;;
*) echo "Blotting out file \"$file\".";;
esac
flength=$(ls -l "$file" | awk '{print $5}') # Field 5 is file length.
pass_count=1
chmod u+w "$file" # Allow overwriting/deleting the file.
echo
while [ "$pass_count" -le "$PASSES" ]
do
echo "Pass #$pass_count"
sync # Flush buffers.
dd if=/dev/urandom of=$file bs=$BLOCKSIZE count=$flength
# Fill with random bytes.
sync # Flush buffers again.
dd if=/dev/zero of=$file bs=$BLOCKSIZE count=$flength
# Fill with zeros.
sync # Flush buffers yet again.
let "pass_count += 1"
echo
done
rm -f $file # Finally, delete scrambled and shredded file.
sync # Flush buffers a final time.
echo "File \"$file\" blotted out and deleted."; echo
exit 0
# This is a fairly secure, if inefficient and slow method
#+ of thoroughly "shredding" a file.
# The "shred" command, part of the GNU "fileutils" package,
#+ does the same thing, although more efficiently.
# The file cannot not be "undeleted" or retrieved by normal methods.
# However . . .
#+ this simple method would *not* likely withstand
#+ sophisticated forensic analysis.
# This script may not play well with a journaled file system.
# Exercise (difficult): Fix it so it does.
# Tom Vier's "wipe" file-deletion package does a much more thorough job
#+ of file shredding than this simple script.
# http://www.ibiblio.org/pub/Linux/utils/file/wipe-2.0.0.tar.bz2
# For an in-depth analysis on the topic of file deletion and security,
#+ see Peter Gutmann's paper,
#+ "Secure Deletion of Data From Magnetic and Solid-State Memory".
# http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html
head -c4 /dev/urandom | od -N4 -tu4 | sed -ne '1s/.* //p'
# Sample output: 1324725719, 3918166450, 2989231420, etc.
# From rnd.sh example script, by Stéphane Chazelas
dd if=/bin/ls | hexdump -C | less
# The -C option nicely formats the output in tabular form.
random000=$(mcookie)
# Generate md5 checksum on the script itself.
random001=`md5sum $0 | awk '{print $1}'`
# Uses 'awk' to strip off the filename.
#!/bin/bash
# tempfile-name.sh: temp filename generator
BASE_STR=`mcookie` # 32-character magic cookie.
POS=11 # Arbitrary position in magic cookie string.
LEN=5 # Get $LEN consecutive characters.
prefix=temp # This is, after all, a "temp" file.
# For more "uniqueness," generate the
#+ filename prefix using the same method
#+ as the suffix, below.
suffix=${BASE_STR:POS:LEN}
# Extract a 5-character string,
#+ starting at position 11.
temp_filename=$prefix.$suffix
# Construct the filename.
echo "Temp filename = "$temp_filename""
# sh tempfile-name.sh
# Temp filename = temp.e19ea
# Compare this method of generating "unique" filenames
#+ with the 'date' method in ex51.sh.
exit 0
#!/bin/bash
# unit-conversion.sh
# Must have 'units' utility installed.
convert_units () # Takes as arguments the units to convert.
{
cf=$(units "$1" "$2" | sed --silent -e '1p' | awk '{print $2}')
# Strip off everything except the actual conversion factor.
echo "$cf"
}
Unit1=miles
Unit2=meters
cfactor=`convert_units $Unit1 $Unit2`
quantity=3.73
result=$(echo $quantity*$cfactor | bc)
echo "There are $result $Unit2 in $quantity $Unit1."
# What happens if you pass incompatible units,
#+ such as "acres" and "miles" to the function?
exit 0
# Exercise: Edit this script to accept command-line parameters,
# with appropriate error checking, of course.
#!/bin/bash
# m4.sh: Using the m4 macro processor
# Strings
string=abcdA01
echo "len($string)" | m4 # 7
echo "substr($string,4)" | m4 # A01
echo "regexp($string,[0-1][0-1],\&Z)" | m4 # 01Z
# Arithmetic
var=99
echo "incr($var)" | m4 # 100
echo "eval($var / 3)" | m4 # 33
exit
xmessage Left click to continue -button okay
case `basename $0` in
"name1" ) do_something;;
"name2" ) do_something_else;;
"name3" ) do_yet_another_thing;;
* ) bail_out;;
esac
cat $file | dd conv=swab,ebcdic &gt; $file_encrypted
# Encode (looks like gibberish).
# Might as well switch bytes (swab), too, for a little extra obscurity.
cat $file_encrypted | dd conv=swab,ascii &gt; $file_plaintext
# Decode.</pre>]
[]
[]
cat $filename &gt;/dev/null
# Contents of the file will not list to stdout.
rm $badname 2&gt;/dev/null
# So error messages [stderr] deep-sixed.
cat $filename 2&gt;/dev/null &gt;/dev/null
# If "$filename" does not exist, there will be no error message output.
# If "$filename" does exist, the contents of the file will not list to stdout.
# Therefore, no output at all will result from the above line of code.
#
# This can be useful in situations where the return code from a command
#+ needs to be tested, but no output is desired.
#
# cat $filename &&gt;/dev/null
# also works, as Baris Cicek points out.
cat /dev/null &gt; /var/log/messages
# : &gt; /var/log/messages has same effect, but does not spawn a new process.
cat /dev/null &gt; /var/log/wtmp
# Obsolete Netscape browser.
# Same principle applies to newer browsers.
if [ -f ~/.netscape/cookies ] # Remove, if exists.
then
rm -f ~/.netscape/cookies
fi
ln -s /dev/null ~/.netscape/cookies
# All cookies now get sent to a black hole, rather than saved to disk.
#!/bin/bash
# Creating a swap file.
# A swap file provides a temporary storage cache
#+ which helps speed up certain filesystem operations.
ROOT_UID=0 # Root has $UID 0.
E_WRONG_USER=85 # Not root?
FILE=/swap
BLOCKSIZE=1024
MINBLOCKS=40
SUCCESS=0
# This script must be run as root.
if [ "$UID" -ne "$ROOT_UID" ]
then
echo; echo "You must be root to run this script."; echo
exit $E_WRONG_USER
fi
blocks=${1:-$MINBLOCKS} # Set to default of 40 blocks,
#+ if nothing specified on command-line.
# This is the equivalent of the command block below.
# --------------------------------------------------
# if [ -n "$1" ]
# then
# blocks=$1
# else
# blocks=$MINBLOCKS
# fi
# --------------------------------------------------
if [ "$blocks" -lt $MINBLOCKS ]
then
blocks=$MINBLOCKS # Must be at least 40 blocks long.
fi
######################################################################
echo "Creating swap file of size $blocks blocks (KB)."
dd if=/dev/zero of=$FILE bs=$BLOCKSIZE count=$blocks # Zero out file.
mkswap $FILE $blocks # Designate it a swap file.
swapon $FILE # Activate swap file.
retcode=$? # Everything worked?
# Note that if one or more of these commands fails,
#+ then it could cause nasty problems.
######################################################################
# Exercise:
# Rewrite the above block of code so that if it does not execute
#+ successfully, then:
# 1) an error message is echoed to stderr,
# 2) all temporary files are cleaned up, and
# 3) the script exits in an orderly fashion with an
#+ appropriate error code.
echo "Swap file created and activated."
exit $retcode
#!/bin/bash
# ramdisk.sh
# A "ramdisk" is a segment of system RAM memory
#+ which acts as if it were a filesystem.
# Its advantage is very fast access (read/write time).
# Disadvantages: volatility, loss of data on reboot or powerdown,
#+ less RAM available to system.
#
# Of what use is a ramdisk?
# Keeping a large dataset, such as a table or dictionary on ramdisk,
#+ speeds up data lookup, since memory access is much faster than disk access.
E_NON_ROOT_USER=70 # Must run as root.
ROOTUSER_NAME=root
MOUNTPT=/mnt/ramdisk # Create with mkdir /mnt/ramdisk.
SIZE=2000 # 2K blocks (change as appropriate)
BLOCKSIZE=1024 # 1K (1024 byte) block size
DEVICE=/dev/ram0 # First ram device
username=`id -nu`
if [ "$username" != "$ROOTUSER_NAME" ]
then
echo "Must be root to run \"`basename $0`\"."
exit $E_NON_ROOT_USER
fi
if [ ! -d "$MOUNTPT" ] # Test whether mount point already there,
then #+ so no error if this script is run
mkdir $MOUNTPT #+ multiple times.
fi
##############################################################################
dd if=/dev/zero of=$DEVICE count=$SIZE bs=$BLOCKSIZE # Zero out RAM device.
# Why is this necessary?
mke2fs $DEVICE # Create an ext2 filesystem on it.
mount $DEVICE $MOUNTPT # Mount it.
chmod 777 $MOUNTPT # Enables ordinary user to access ramdisk.
# However, must be root to unmount it.
##############################################################################
# Need to test whether above commands succeed. Could cause problems otherwise.
# Exercise: modify this script to make it safer.
echo "\"$MOUNTPT\" now available for use."
# The ramdisk is now accessible for storing files, even by an ordinary user.
# Caution, the ramdisk is volatile, and its contents will disappear
#+ on reboot or power loss.
# Copy anything you want saved to a regular directory.
# After reboot, run this script to again set up ramdisk.
# Remounting /mnt/ramdisk without the other steps will not work.
# Suitably modified, this script can by invoked in /etc/rc.d/rc.local,
#+ to set up ramdisk automatically at bootup.
# That may be appropriate on, for example, a database server.
exit 0</pre>]
fun () { echo "This is a function"; echo; }
# ^ ^
fun () { echo "This is a function"; echo } # Error!
# ^
fun2 () { echo "Even a single-command function? Yes!"; }
# ^
#!/bin/bash
# ex59.sh: Exercising functions (simple).
JUST_A_SECOND=1
funky ()
{ # This is about as simple as functions get.
echo "This is a funky function."
echo "Now exiting funky function."
} # Function declaration must precede call.
fun ()
{ # A somewhat more complex function.
i=0
REPEATS=30
echo
echo "And now the fun really begins."
echo
sleep $JUST_A_SECOND # Hey, wait a second!
while [ $i -lt $REPEATS ]
do
echo "----------FUNCTIONS----------&gt;"
echo "<------------ARE-------------"
echo "<------------FUN------------&gt;"
echo
let "i+=1"
done
}
# Now, call the functions.
funky
fun
exit $?
f1
# Will give an error message, since function "f1" not yet defined.
declare -f f1 # This doesn't help either.
f1 # Still an error message.
# However...
f1 ()
{
echo "Calling function \"f2\" from within function \"f1\"."
f2
}
f2 ()
{
echo "Function \"f2\"."
}
f1 # Function "f2" is not actually called until this point,
#+ although it is referenced before its definition.
# This is permissible.
# Thanks, S.C.
#!/bin/bash
# empty-function.sh
empty ()
{
}
exit 0 # Will not exit here!
# $ sh empty-function.sh
# empty-function.sh: line 6: syntax error near unexpected token `}'
# empty-function.sh: line 6: `}'
# $ echo $?
# 2
# Note that a function containing only comments is empty.
func ()
{
# Comment 1.
# Comment 2.
# This is still an empty function.
# Thank you, Mark Bova, for pointing this out.
}
# Results in same error message as above.
# However ...
not_quite_empty ()
{
illegal_command
} # A script containing this function will *not* bomb
#+ as long as the function is not called.
not_empty ()
{
:
} # Contains a : (null command), and this is okay.
# Thank you, Dominick Geyer and Thiemo Kellner.
f1 ()
{
f2 () # nested
{
echo "Function \"f2\", inside \"f1\"."
}
}
f2 # Gives an error message.
# Even a preceding "declare -f f2" wouldn't help.
echo
f1 # Does nothing, since calling "f1" does not automatically call "f2".
f2 # Now, it's all right to call "f2",
#+ since its definition has been made visible by calling "f1".
# Thanks, S.C.
ls -l | foo() { echo "foo"; } # Permissible, but useless.
if [ "$USER" = bozo ]
then
bozo_greet () # Function definition embedded in an if/then construct.
{
echo "Hello, Bozo."
}
fi
bozo_greet # Works only for Bozo, and other users get an error.
# Something like this might be useful in some contexts.
NO_EXIT=1 # Will enable function definition below.
[[ $NO_EXIT -eq 1 ]] && exit() { true; } # Function definition in an "and-list".
# If $NO_EXIT is 1, declares "exit ()".
# This disables the "exit" builtin by aliasing it to "true".
exit # Invokes "exit ()" function, not "exit" builtin.
# Or, similarly:
filename=file1
[ -f "$filename" ] &&
foo () { rm -f "$filename"; echo "File "$filename" deleted."; } ||
foo () { echo "File "$filename" not found."; touch bar; }
foo
# Thanks, S.C. and Christopher Head
_(){ for i in {1..10}; do echo -n "$FUNCNAME"; done; echo; }
# ^^^ No space between function name and parentheses.
# This doesn't always work. Why not?
# Now, let's invoke the function.
_ # __________
# ^^^^^^^^^^ 10 underscores (10 x function name)!
# A "naked" underscore is an acceptable function name.
# In fact, a colon is likewise an acceptable function name.
:(){ echo ":"; }; :
# Of what use is this?
# It's a devious way to obfuscate the code in a script.
# As Yan Chen points out,
# when a function is defined multiple times,
# the final version is what is invoked.
# This is not, however, particularly useful.
func ()
{
echo "First version of func ()."
}
func ()
{
echo "Second version of func ()."
}
func # Second version of func ().
exit $?
# It is even possible to use functions to override
#+ or preempt system commands.
# Of course, this is *not* advisable.</pre>]
o | x |
----------
| x |
----------
| o |
Your move, human (row, column)?
Jones,Bill,235 S. Williams St.,Denver,CO,80221,(303) 244-7989
Smith,Tom,404 Polk Ave.,Los Angeles,CA,90003,(213) 879-5612
...
# (Isaac) Newton's Method for speedy extraction
#+ of square roots.
guess = $argument
# $argument is the number to find the square root of.
# $guess is each successive calculated "guess" -- or trial solution --
#+ of the square root.
# Our first "guess" at a square root is the argument itself.
oldguess = 0
# $oldguess is the previous $guess.
tolerance = .000001
# To how close a tolerance we wish to calculate.
loopcnt = 0
# Let's keep track of how many times through the loop.
# Some arguments will require more loop iterations than others.
while [ ABS( $guess $oldguess ) -gt $tolerance ]
# ^^^^^^^^^^^^^^^^^^^^^^^ Fix up syntax, of course.
# "ABS" is a (floating point) function to find the absolute value
#+ of the difference between the two terms.
# So, as long as difference between current and previous
#+ trial solution (guess) exceeds the tolerance, keep looping.
do
oldguess = $guess # Update $oldguess to previous $guess.
# =======================================================
guess = ( $oldguess + ( $argument / $oldguess ) ) / 2.0
# = 1/2 ( ($oldguess **2 + $argument) / $oldguess )
# equivalent to:
# = 1/2 ( $oldguess + $argument / $oldguess )
# that is, "averaging out" the trial solution and
#+ the proportion of argument deviation
#+ (in effect, splitting the error in half).
# This converges on an accurate solution
#+ with surprisingly few loop iterations . . .
#+ for arguments &gt; $tolerance, of course.
# =======================================================
(( loopcnt++ )) # Update loop counter.
done
mark --&gt; park --&gt; part --&gt; past --&gt; vast --&gt; vase
^ ^ ^ ^ ^
C O D E S
A B F G H
I K L M N
P Q R T U
V W X Y Z
Each letter of the alphabet appears once, except "I" also represents
"J". The arbitrarily chosen key word, "CODES" comes first, then all
the rest of the alphabet, in order from left to right, skipping letters
already used.
To encrypt, separate the plaintext message into digrams (2-letter
groups). If a group has two identical letters, delete the second, and
form a new group. If there is a single letter left over at the end,
insert a "null" character, typically an "X."
THIS IS A TOP SECRET MESSAGE
TH IS IS AT OP SE CR ET ME SA GE
For each digram, there are three possibilities.
-----------------------------------------------
1) Both letters will be on the same row of the key square:
For each letter, substitute the one immediately to the right, in that
row. If necessary, wrap around left to the beginning of the row.
or
2) Both letters will be in the same column of the key square:
For each letter, substitute the one immediately below it, in that
row. If necessary, wrap around to the top of the column.
or
3) Both letters will form the corners of a rectangle within the key square:
For each letter, substitute the one on the other corner the rectangle
which lies on the same row.
The "TH" digram falls under case #3.
G H
M N
T U (Rectangle with "T" and "H" at corners)
T --&gt; U
H --&gt; G
The "SE" digram falls under case #1.
C O D E S (Row containing "S" and "E")
S --&gt; C (wraps around left to beginning of row)
E --&gt; S
=========================================================================
To decrypt encrypted text, reverse the above procedure under cases #1
and #2 (move in opposite direction for substitution). Under case #3,
just take the remaining two corners of the rectangle.
Helen Fouche Gaines' classic work, ELEMENTARY CRYPTANALYSIS (1939), gives a
fairly detailed description of the Playfair Cipher and its solution methods.
For the simple case of a 2 x 2 determinant:
|a b|
|b a|
The solution is a*a - b*b, where "a" and "b" represent numbers.</pre>]
# file: UseGetOpt-2
# UseGetOpt-2.sh parameter-completion
_UseGetOpt-2 () # By convention, the function name
{ #+ starts with an underscore.
local cur
# Pointer to current completion word.
# By convention, it's named "cur" but this isn't strictly necessary.
COMPREPLY=() # Array variable storing the possible completions.
cur=${COMP_WORDS[COMP_CWORD]}
case "$cur" in
-*)
COMPREPLY=( $( compgen -W '-a -d -f -l -t -h --aoption --debug \
--file --log --test --help --' -- $cur ) );;
# Generate the completion matches and load them into $COMPREPLY array.
# xx) May add more cases here.
# yy)
# zz)
esac
return 0
}
complete -F _UseGetOpt-2 -o filenames ./UseGetOpt-2.sh
# ^^ ^^^^^^^^^^^^ Invokes the function _UseGetOpt-2.</pre>]
[]
[]
#!/bin/bash
# nested-loop.sh: Nested "for" loops.
outer=1 # Set outer loop counter.
# Beginning of outer loop.
for a in 1 2 3 4 5
do
echo "Pass $outer in outer loop."
echo "---------------------"
inner=1 # Reset inner loop counter.
# ===============================================
# Beginning of inner loop.
for b in 1 2 3 4 5
do
echo "Pass $inner in inner loop."
let "inner+=1" # Increment inner loop counter.
done
# End of inner loop.
# ===============================================
let "outer+=1" # Increment outer loop counter.
echo # Space between output blocks in pass of outer loop.
done
# End of outer loop.
exit 0</pre>]
#!/bin/bash4
# fetch_address.sh
declare -A address
# -A option declares associative array.
address[Charles]="414 W. 10th Ave., Baltimore, MD 21236"
address[John]="202 E. 3rd St., New York, NY 10009"
address[Wilma]="1854 Vermont Ave, Los Angeles, CA 90023"
echo "Charles's address is ${address[Charles]}."
# Charles's address is 414 W. 10th Ave., Baltimore, MD 21236.
echo "Wilma's address is ${address[Wilma]}."
# Wilma's address is 1854 Vermont Ave, Los Angeles, CA 90023.
echo "John's address is ${address[John]}."
# John's address is 202 E. 3rd St., New York, NY 10009.
echo
echo "${!address[*]}" # The array indices ...
# Charles John Wilma
#!/bin/bash4
# fetch_address-2.sh
# A more elaborate version of fetch_address.sh.
SUCCESS=0
E_DB=99 # Error code for missing entry.
declare -A address
# -A option declares associative array.
store_address ()
{
address[$1]="$2"
return $?
}
fetch_address ()
{
if [[ -z "${address[$1]}" ]]
then
echo "$1's address is not in database."
return $E_DB
fi
echo "$1's address is ${address[$1]}."
return $?
}
store_address "Lucas Fayne" "414 W. 13th Ave., Baltimore, MD 21236"
store_address "Arvid Boyce" "202 E. 3rd St., New York, NY 10009"
store_address "Velma Winston" "1854 Vermont Ave, Los Angeles, CA 90023"
# Exercise:
# Rewrite the above store_address calls to read data from a file,
#+ then assign field 1 to name, field 2 to address in the array.
# Each line in the file would have a format corresponding to the above.
# Use a while-read loop to read from file, sed or awk to parse the fields.
fetch_address "Lucas Fayne"
# Lucas Fayne's address is 414 W. 13th Ave., Baltimore, MD 21236.
fetch_address "Velma Winston"
# Velma Winston's address is 1854 Vermont Ave, Los Angeles, CA 90023.
fetch_address "Arvid Boyce"
# Arvid Boyce's address is 202 E. 3rd St., New York, NY 10009.
fetch_address "Bozo Bozeman"
# Bozo Bozeman's address is not in database.
exit $? # In this case, exit code = 99, since that is function return.
address[ ]="Blank" # Error!
#!/bin/bash4
test_char ()
{
case "$1" in
[[:print:]] ) echo "$1 is a printable character.";;& # |
# The ;;& terminator continues to the next pattern test. |
[[:alnum:]] ) echo "$1 is an alpha/numeric character.";;& # v
[[:alpha:]] ) echo "$1 is an alphabetic character.";;& # v
[[:lower:]] ) echo "$1 is a lowercase alphabetic character.";;&
[[:digit:]] ) echo "$1 is an numeric character.";& # |
# The ;& terminator executes the next statement ... # |
%%%@@@@@ ) echo "********************************";; # v
# ^^^^^^^^ ... even with a dummy pattern.
esac
}
echo
test_char 3
# 3 is a printable character.
# 3 is an alpha/numeric character.
# 3 is an numeric character.
# ********************************
echo
test_char m
# m is a printable character.
# m is an alpha/numeric character.
# m is an alphabetic character.
# m is a lowercase alphabetic character.
echo
test_char /
# / is a printable character.
echo
# The ;;& terminator can save complex if/then conditions.
# The ;& is somewhat less useful.
#!/bin/bash4
# A coprocess communicates with a while-read loop.
coproc { cat mx_data.txt; sleep 2; }
# ^^^^^^^
# Try running this without "sleep 2" and see what happens.
while read -u ${COPROC[0]} line # ${COPROC[0]} is the
do #+ file descriptor of the coprocess.
echo "$line" | sed -e 's/line/NOT-ORIGINAL-TEXT/'
done
kill $COPROC_PID # No longer need the coprocess,
#+ so kill its PID.
#!/bin/bash4
echo; echo
a=aaa
b=bbb
c=ccc
coproc echo "one two three"
while read -u ${COPROC[0]} a b c; # Note that this loop
do #+ runs in a subshell.
echo "Inside while-read loop: ";
echo "a = $a"; echo "b = $b"; echo "c = $c"
echo "coproc file descriptor: ${COPROC[0]}"
done
# a = one
# b = two
# c = three
# So far, so good, but ...
echo "-----------------"
echo "Outside while-read loop: "
echo "a = $a" # a =
echo "b = $b" # b =
echo "c = $c" # c =
echo "coproc file descriptor: ${COPROC[0]}"
echo
# The coproc is still running, but ...
#+ it still doesn't enable the parent process
#+ to "inherit" variables from the child process, the while-read loop.
# Compare this to the "badread.sh" script.
#!/bin/bash4
coproc cpname { for i in {0..10}; do echo "index = $i"; done; }
# ^^^^^^ This is a *named* coprocess.
read -u ${cpname[0]}
echo $REPLY # index = 0
echo ${COPROC[0]} #+ No output ... the coprocess timed out
# after the first loop iteration.
# However, George Dimitriu has a partial fix.
coproc cpname { for i in {0..10}; do echo "index = $i"; done; sleep 1;
echo hi &gt; myo; cat - &gt;&gt; myo; }
# ^^^^^ This is a *named* coprocess.
echo "I am main"$'\04' &gt;&${cpname[1]}
myfd=${cpname[0]}
echo myfd=$myfd
### while read -u $myfd
### do
### echo $REPLY;
### done
echo $cpname_PID
# Run this with and without the commented-out while-loop, and it is
#+ apparent that each process, the executing shell and the coprocess,
#+ waits for the other to finish writing in its own write-enabled pipe.
#!/bin/bash4
mapfile Arr1 < $0
# Same result as Arr1=( $(cat $0) )
echo "${Arr1[@]}" # Copies this entire script out to stdout.
echo "--"; echo
# But, not the same as read -a !!!
read -a Arr2 < $0
echo "${Arr2[@]}" # Reads only first line of script into the array.
exit
#!/bin/bash4
var=veryMixedUpVariable
echo ${var} # veryMixedUpVariable
echo ${var^} # VeryMixedUpVariable
# * First char --&gt; uppercase.
echo ${var^^} # VERYMIXEDUPVARIABLE
# ** All chars --&gt; uppercase.
echo ${var,} # veryMixedUpVariable
# * First char --&gt; lowercase.
echo ${var,,} # verymixedupvariable
# ** All chars --&gt; lowercase.
#!/bin/bash4
declare -l var1 # Will change to lowercase
var1=MixedCaseVARIABLE
echo "$var1" # mixedcasevariable
# Same effect as echo $var1 | tr A-Z a-z
declare -c var2 # Changes only initial char to uppercase.
var2=originally_lowercase
echo "$var2" # Originally_lowercase
# NOT the same effect as echo $var2 | tr a-z A-Z
#!/bin/bash4
echo {40..60..2}
# 40 42 44 46 48 50 52 54 56 58 60
# All the even numbers, between 40 and 60.
echo {60..40..2}
# 60 58 56 54 52 50 48 46 44 42 40
# All the even numbers, between 40 and 60, counting backwards.
# In effect, a decrement.
echo {60..40..-2}
# The same output. The minus sign is not necessary.
# But, what about letters and symbols?
echo {X..d}
# X Y Z [ ] ^ _ ` a b c d
# Does not echo the \ which escapes a space.
#!/bin/bash
# show-params.bash
# Requires version 4+ of Bash.
# Invoke this scripts with at least one positional parameter.
E_BADPARAMS=99
if [ -z "$1" ]
then
echo "Usage $0 param1 ..."
exit $E_BADPARAMS
fi
echo ${@:0}
# bash3 show-params.bash4 one two three
# one two three
# bash4 show-params.bash4 one two three
# show-params.bash4 one two three
# $0 $1 $2 $3
#!/bin/bash4
# filelist.bash4
shopt -s globstar # Must enable globstar, otherwise ** doesn't work.
# The globstar shell option is new to version 4 of Bash.
echo "Using *"; echo
for filename in *
do
echo "$filename"
done # Lists only files in current directory ($PWD).
echo; echo "--------------"; echo
echo "Using **"
for filename in **
do
echo "$filename"
done # Lists complete file tree, recursively.
exit
Using *
allmyfiles
filelist.bash4
--------------
Using **
allmyfiles
allmyfiles/file.index.txt
allmyfiles/my_music
allmyfiles/my_music/me-singing-60s-folksongs.ogg
allmyfiles/my_music/me-singing-opera.ogg
allmyfiles/my_music/piano-lesson.1.ogg
allmyfiles/my_pictures
allmyfiles/my_pictures/at-beach-with-Jade.png
allmyfiles/my_pictures/picnic-with-Melissa.png
filelist.bash4
#!/bin/bash4
command_not_found_handle ()
{ # Accepts implicit parameters.
echo "The following command is not valid: \""$1\"""
echo "With the following argument(s): \""$2\"" \""$3\""" # $4, $5 ...
} # $1, $2, etc. are not explicitly passed to the function.
bad_command arg1 arg2
# The following command is not valid: "bad_command"
# With the following argument(s): "arg1" "arg2"
#!/bin/bash
# Requires Bash version -ge 4.1 ...
num_chars=61
read -N $num_chars var < $0 # Read first 61 characters of script!
echo "$var"
exit
####### Output of Script #######
#!/bin/bash
# Requires Bash version -ge 4.1 ...
num_chars=61
#!/bin/bash
# here-commsub.sh
# Requires Bash version -ge 4.1 ...
multi_line_var=$( cat <<ENDxxx
------------------------------
This is line 1 of the variable
This is line 2 of the variable
This is line 3 of the variable
------------------------------
ENDxxx)
# Rather than what Bash 4.0 requires:
#+ that the terminating limit string and
#+ the terminating close-parenthesis be on separate lines.
# ENDxxx
# )
echo "$multi_line_var"
# Bash still emits a warning, though.
# warning: here-document at line 10 delimited
#+ by end-of-file (wanted `ENDxxx')
echo -e '\u2630' # Horizontal triple bar character.
# Equivalent to the more roundabout:
echo -e "\xE2\x98\xB0"
# Recognized by earlier Bash versions.
echo -e '\u220F' # PI (Greek letter and mathematical symbol)
echo -e '\u0416' # Capital "ZHE" (Cyrillic letter)
echo -e '\u2708' # Airplane (Dingbat font) symbol
echo -e '\u2622' # Radioactivity trefoil
echo -e "The amplifier circuit requires a 100 \u2126 pull-up resistor."
unicode_var='\u2640'
echo -e $unicode_var # Female symbol
printf "$unicode_var \n" # Female symbol, with newline
# And for something a bit more elaborate . . .
# We can store Unicode symbols in an associative array,
#+ then retrieve them by name.
# Run this in a gnome-terminal or a terminal with a large, bold font
#+ for better legibility.
declare -A symbol # Associative array.
symbol[script_E]='\u2130'
symbol[script_F]='\u2131'
symbol[script_J]='\u2110'
symbol[script_M]='\u2133'
symbol[Rx]='\u211E'
symbol[TEL]='\u2121'
symbol[FAX]='\u213B'
symbol[care_of]='\u2105'
symbol[account]='\u2100'
symbol[trademark]='\u2122'
echo -ne "${symbol[script_E]} "
echo -ne "${symbol[script_F]} "
echo -ne "${symbol[script_J]} "
echo -ne "${symbol[script_M]} "
echo -ne "${symbol[Rx]} "
echo -ne "${symbol[TEL]} "
echo -ne "${symbol[FAX]} "
echo -ne "${symbol[care_of]} "
echo -ne "${symbol[account]} "
echo -ne "${symbol[trademark]} "
echo
#!/bin/bash
# lastpipe-option.sh
line='' # Null value.
echo "\$line = "$line"" # $line =
echo
shopt -s lastpipe # Error on Bash version -lt 4.2.
echo "Exit status of attempting to set \"lastpipe\" option is $?"
# 1 if Bash version -lt 4.2, 0 otherwise.
echo
head -1 $0 | read line # Pipe the first line of the script to read.
# ^^^^^^^^^ Not in a subshell!!!
echo "\$line = "$line""
# Older Bash releases $line =
# Bash version 4.2 $line = #!/bin/bash
#!/bin/bash
# neg-array.sh
# Requires Bash, version -ge 4.2.
array=( zero one two three four five ) # Six-element array.
# 0 1 2 3 4 5
# -6 -5 -4 -3 -2 -1
# Negative array indices now permitted.
echo ${array[-1]} # five
echo ${array[-2]} # four
# ...
echo ${array[-6]} # zero
# Negative array indices count backward from the last element+1.
# But, you cannot index past the beginning of the array.
echo ${array[-7]} # array: bad array subscript
# So, what is this new feature good for?
echo "The last element in the array is "${array[-1]}""
# Which is quite a bit more straightforward than:
echo "The last element in the array is "${array[${#array[*]}-1]}""
echo
# And ...
index=0
let "neg_element_count = 0 - ${#array[*]}"
# Number of elements, converted to a negative number.
while [ $index -gt $neg_element_count ]; do
((index--)); echo -n "${array[index]} "
done # Lists the elements in the array, backwards.
# We have just simulated the "tac" command on this array.
echo
# See also neg-offset.sh.
#!/bin/bash
# Bash, version -ge 4.2
# Negative length-index in substring extraction.
# Important: It changes the interpretation of this construct!
stringZ=abcABC123ABCabc
echo ${stringZ} # abcABC123ABCabc
# Position within string: 0123456789.....
echo ${stringZ:2:3} # cAB
# Count 2 chars forward from string beginning, and extract 3 chars.
# ${string:position:length}
# So far, nothing new, but now ...
# abcABC123ABCabc
# Position within string: 0123....6543210
echo ${stringZ:3:-6} # ABC123
# ^
# Index 3 chars forward from beginning and 6 chars backward from end,
#+ and extract everything in between.
# ${string:offset-from-front:offset-from-end}
# When the "length" parameter is negative,
#+ it serves as an offset-from-end parameter.
# See also neg-array.sh.</pre>]
[]
[]
(( 0 && 1 )) # Logical AND
echo $? # 1 ***
# And so ...
let "num = (( 0 && 1 ))"
echo $num # 0
# But ...
let "num = (( 0 && 1 ))"
echo $? # 1 ***
(( 200 || 11 )) # Logical OR
echo $? # 0 ***
# ...
let "num = (( 200 || 11 ))"
echo $num # 1
let "num = (( 200 || 11 ))"
echo $? # 0 ***
(( 200 | 11 )) # Bitwise OR
echo $? # 0 ***
# ...
let "num = (( 200 | 11 ))"
echo $num # 203
let "num = (( 200 | 11 ))"
echo $? # 0 ***
# The "let" construct returns the same exit status
#+ as the double-parentheses arithmetic expansion.
var=-2 && (( var+=2 ))
echo $? # 1
var=-2 && (( var+=2 )) && echo $var
# Will not echo $var!
if cmp a b &&gt; /dev/null # Suppress output.
then echo "Files a and b are identical."
else echo "Files a and b differ."
fi
# The very useful "if-grep" construct:
# -----------------------------------
if grep -q Bash file
then echo "File contains at least one occurrence of Bash."
fi
word=Linux
letter_sequence=inu
if echo "$word" | grep -q "$letter_sequence"
# The "-q" option to grep suppresses output.
then
echo "$letter_sequence found in $word"
else
echo "$letter_sequence not found in $word"
fi
if COMMAND_WHOSE_EXIT_STATUS_IS_0_UNLESS_ERROR_OCCURRED
then echo "Command succeeded."
else echo "Command failed."
fi
#!/bin/bash
# Tip:
# If you're unsure how a certain condition might evaluate,
#+ test it in an if-test.
echo
echo "Testing \"0\""
if [ 0 ] # zero
then
echo "0 is true."
else # Or else ...
echo "0 is false."
fi # 0 is true.
echo
echo "Testing \"1\""
if [ 1 ] # one
then
echo "1 is true."
else
echo "1 is false."
fi # 1 is true.
echo
echo "Testing \"-1\""
if [ -1 ] # minus one
then
echo "-1 is true."
else
echo "-1 is false."
fi # -1 is true.
echo
echo "Testing \"NULL\""
if [ ] # NULL (empty condition)
then
echo "NULL is true."
else
echo "NULL is false."
fi # NULL is false.
echo
echo "Testing \"xyz\""
if [ xyz ] # string
then
echo "Random string is true."
else
echo "Random string is false."
fi # Random string is true.
echo
echo "Testing \"\$xyz\""
if [ $xyz ] # Tests if $xyz is null, but...
# it's only an uninitialized variable.
then
echo "Uninitialized variable is true."
else
echo "Uninitialized variable is false."
fi # Uninitialized variable is false.
echo
echo "Testing \"-n \$xyz\""
if [ -n "$xyz" ] # More pedantically correct.
then
echo "Uninitialized variable is true."
else
echo "Uninitialized variable is false."
fi # Uninitialized variable is false.
echo
xyz= # Initialized, but set to null value.
echo "Testing \"-n \$xyz\""
if [ -n "$xyz" ]
then
echo "Null variable is true."
else
echo "Null variable is false."
fi # Null variable is false.
echo
# When is "false" true?
echo "Testing \"false\""
if [ "false" ] # It seems that "false" is just a string ...
then
echo "\"false\" is true." #+ and it tests true.
else
echo "\"false\" is false."
fi # "false" is true.
echo
echo "Testing \"\$false\"" # Again, uninitialized variable.
if [ "$false" ]
then
echo "\"\$false\" is true."
else
echo "\"\$false\" is false."
fi # "$false" is false.
# Now, we get the expected result.
# What would happen if we tested the uninitialized variable "$true"?
echo
exit 0
if [ condition-true ]
then
command 1
command 2
...
else # Or else ...
# Adds default code block executing if original condition tests false.
command 3
command 4
...
fi
if [ -x "$filename" ]; then
if [ condition1 ]
then
command1
command2
command3
elif [ condition2 ]
# Same as else if
then
command4
command5
else
default-command
fi
#!/bin/bash
echo
if test -z "$1"
then
echo "No command-line arguments."
else
echo "First command-line argument is $1."
fi
echo
if /usr/bin/test -z "$1" # Equivalent to "test" builtin.
# ^^^^^^^^^^^^^ # Specifying full pathname.
then
echo "No command-line arguments."
else
echo "First command-line argument is $1."
fi
echo
if [ -z "$1" ] # Functionally identical to above code blocks.
# if [ -z "$1" should work, but...
#+ Bash responds to a missing close-bracket with an error message.
then
echo "No command-line arguments."
else
echo "First command-line argument is $1."
fi
echo
if /usr/bin/[ -z "$1" ] # Again, functionally identical to above.
# if /usr/bin/[ -z "$1" # Works, but gives an error message.
# # Note:
# This has been fixed in Bash, version 3.x.
then
echo "No command-line arguments."
else
echo "First command-line argument is $1."
fi
echo
exit 0
file=/etc/passwd
if [[ -e $file ]]
then
echo "Password file exists."
fi
# [[ Octal and hexadecimal evaluation ]]
# Thank you, Moritz Gronbach, for pointing this out.
decimal=15
octal=017 # = 15 (decimal)
hex=0x0f # = 15 (decimal)
if [ "$decimal" -eq "$octal" ]
then
echo "$decimal equals $octal"
else
echo "$decimal is not equal to $octal" # 15 is not equal to 017
fi # Doesn't evaluate within [ single brackets ]!
if [[ "$decimal" -eq "$octal" ]]
then
echo "$decimal equals $octal" # 15 equals 017
else
echo "$decimal is not equal to $octal"
fi # Evaluates within [[ double brackets ]]!
if [[ "$decimal" -eq "$hex" ]]
then
echo "$decimal equals $hex" # 15 equals 0x0f
else
echo "$decimal is not equal to $hex"
fi # [[ $hexadecimal ]] also evaluates!
dir=/home/bozo
if cd "$dir" 2&gt;/dev/null; then # "2&gt;/dev/null" hides error message.
echo "Now in $dir."
else
echo "Can't change to $dir."
fi
var1=20
var2=22
[ "$var1" -ne "$var2" ] && echo "$var1 is not equal to $var2"
home=/home/bozo
[ -d "$home" ] || echo "$home directory does not exist."
#!/bin/bash
# arith-tests.sh
# Arithmetic tests.
# The (( ... )) construct evaluates and tests numerical expressions.
# Exit status opposite from [ ... ] construct!
(( 0 ))
echo "Exit status of \"(( 0 ))\" is $?." # 1
(( 1 ))
echo "Exit status of \"(( 1 ))\" is $?." # 0
(( 5 &gt; 4 )) # true
echo "Exit status of \"(( 5 &gt; 4 ))\" is $?." # 0
(( 5 &gt; 9 )) # false
echo "Exit status of \"(( 5 &gt; 9 ))\" is $?." # 1
(( 5 == 5 )) # true
echo "Exit status of \"(( 5 == 5 ))\" is $?." # 0
# (( 5 = 5 )) gives an error message.
(( 5 - 5 )) # 0
echo "Exit status of \"(( 5 - 5 ))\" is $?." # 1
(( 5 / 4 )) # Division o.k.
echo "Exit status of \"(( 5 / 4 ))\" is $?." # 0
(( 1 / 2 )) # Division result < 1.
echo "Exit status of \"(( 1 / 2 ))\" is $?." # Rounded off to 0.
# 1
(( 1 / 0 )) 2&gt;/dev/null # Illegal division by 0.
# ^^^^^^^^^^^
echo "Exit status of \"(( 1 / 0 ))\" is $?." # 1
# What effect does the "2&gt;/dev/null" have?
# What would happen if it were removed?
# Try removing it, then rerunning the script.
# ======================================= #
# (( ... )) also useful in an if-then test.
var1=5
var2=4
if (( var1 &gt; var2 ))
then #^ ^ Note: Not $var1, $var2. Why?
echo "$var1 is greater than $var2"
fi # 5 is greater than 4
exit 0</pre>]
your_id=${USER}-on-${HOSTNAME}
echo "$your_id"
#
echo "Old \$PATH = $PATH"
PATH=${PATH}:/opt/bin # Add /opt/bin to $PATH for duration of script.
echo "New \$PATH = $PATH"
var1=1
var2=2
# var3 is unset.
echo ${var1-$var2} # 1
echo ${var3-$var2} # 2
# ^ Note the $ prefix.
echo ${username-`whoami`}
# Echoes the result of `whoami`, if variable $username is still unset.
#!/bin/bash
# param-sub.sh
# Whether a variable has been declared
#+ affects triggering of the default option
#+ even if the variable is null.
username0=
echo "username0 has been declared, but is set to null."
echo "username0 = ${username0-`whoami`}"
# Will not echo.
echo
echo username1 has not been declared.
echo "username1 = ${username1-`whoami`}"
# Will echo.
username2=
echo "username2 has been declared, but is set to null."
echo "username2 = ${username2:-`whoami`}"
# ^
# Will echo because of :- rather than just - in condition test.
# Compare to first instance, above.
#
# Once again:
variable=
# variable has been declared, but is set to null.
echo "${variable-0}" # (no output)
echo "${variable:-1}" # 1
# ^
unset variable
echo "${variable-2}" # 2
echo "${variable:-3}" # 3
exit 0
DEFAULT_FILENAME=generic.data
filename=${1:-$DEFAULT_FILENAME}
# If not otherwise specified, the following command block operates
#+ on the file "generic.data".
# Begin-Command-Block
# ...
# ...
# ...
# End-Command-Block
# From "hanoi2.bash" example:
DISKS=${1:-E_NOPARAM} # Must specify how many disks.
# Set $DISKS to $1 command-line-parameter,
#+ or to $E_NOPARAM if that is unset.
echo ${var=abc} # abc
echo ${var=xyz} # abc
# $var had already been set to abc, so it did not change.
echo "###### \${parameter+alt_value} ########"
echo
a=${param1+xyz}
echo "a = $a" # a =
param2=
a=${param2+xyz}
echo "a = $a" # a = xyz
param3=123
a=${param3+xyz}
echo "a = $a" # a = xyz
echo
echo "###### \${parameter:+alt_value} ########"
echo
a=${param4:+xyz}
echo "a = $a" # a =
param5=
a=${param5:+xyz}
echo "a = $a" # a =
# Different result from a=${param5+xyz}
param6=123
a=${param6:+xyz}
echo "a = $a" # a = xyz
#!/bin/bash
# Check some of the system's environmental variables.
# This is good preventative maintenance.
# If, for example, $USER, the name of the person at the console, is not set,
#+ the machine will not recognize you.
: ${HOSTNAME?} ${USER?} ${HOME?} ${MAIL?}
echo
echo "Name of the machine is $HOSTNAME."
echo "You are $USER."
echo "Your home directory is $HOME."
echo "Your mail INBOX is located in $MAIL."
echo
echo "If you are reading this message,"
echo "critical environmental variables have been set."
echo
echo
# ------------------------------------------------------
# The ${variablename?} construction can also check
#+ for variables set within the script.
ThisVariable=Value-of-ThisVariable
# Note, by the way, that string variables may be set
#+ to characters disallowed in their names.
: ${ThisVariable?}
echo "Value of ThisVariable is $ThisVariable".
echo; echo
: ${ZZXy23AB?"ZZXy23AB has not been set."}
# Since ZZXy23AB has not been set,
#+ then the script terminates with an error message.
# You can specify the error message.
# : ${variablename?"ERROR MESSAGE"}
# Same result with: dummy_variable=${ZZXy23AB?}
# dummy_variable=${ZZXy23AB?"ZXy23AB has not been set."}
#
# echo ${ZZXy23AB?} &gt;/dev/null
# Compare these methods of checking whether a variable has been set
#+ with "set -u" . . .
echo "You will not see this message, because script already terminated."
HERE=0
exit $HERE # Will NOT exit here.
# In fact, this script will return an exit status (echo $?) of 1.
#!/bin/bash
# usage-message.sh
: ${1?"Usage: $0 ARGUMENT"}
# Script exits here if command-line parameter absent,
#+ with following error message.
# usage-message.sh: 1: Usage: usage-message.sh ARGUMENT
echo "These two lines echo only if command-line parameter given."
echo "command-line parameter = \"$1\""
exit 0 # Will exit here only if command-line parameter present.
# Check the exit status, both with and without command-line parameter.
# If command-line parameter present, then "$?" is 0.
# If not, then "$?" is 1.
#!/bin/bash
# length.sh
E_NO_ARGS=65
if [ $# -eq 0 ] # Must have command-line args to demo script.
then
echo "Please invoke this script with one or more command-line arguments."
exit $E_NO_ARGS
fi
var01=abcdEFGH28ij
echo "var01 = ${var01}"
echo "Length of var01 = ${#var01}"
# Now, let's try embedding a space.
var02="abcd EFGH28ij"
echo "var02 = ${var02}"
echo "Length of var02 = ${#var02}"
echo "Number of command-line arguments passed to script = ${#@}"
echo "Number of command-line arguments passed to script = ${#*}"
exit 0
# Function from "days-between.sh" example.
# Strips leading zero(s) from argument passed.
strip_leading_zero () # Strip possible leading zero(s)
{ #+ from argument passed.
return=${1#0} # The "1" refers to "$1" -- passed arg.
} # The "0" is what to remove from "$1" -- strips zeros.
strip_leading_zero2 () # Strip possible leading zero(s), since otherwise
{ # Bash will interpret such numbers as octal values.
shopt -s extglob # Turn on extended globbing.
local val=${1##+(0)} # Use local variable, longest matching series of 0's.
shopt -u extglob # Turn off extended globbing.
_strip_leading_zero2=${val:-0}
# If input was 0, return 0 instead of "".
}
echo `basename $PWD` # Basename of current working directory.
echo "${PWD##*/}" # Basename of current working directory.
echo
echo `basename $0` # Name of script.
echo $0 # Name of script.
echo "${0##*/}" # Name of script.
echo
filename=test.data
echo "${filename##*.}" # data
# Extension of filename.
#!/bin/bash
# patt-matching.sh
# Pattern matching using the # ## % %% parameter substitution operators.
var1=abcd12345abc6789
pattern1=a*c # * (wild card) matches everything between a - c.
echo
echo "var1 = $var1" # abcd12345abc6789
echo "var1 = ${var1}" # abcd12345abc6789
# (alternate form)
echo "Number of characters in ${var1} = ${#var1}"
echo
echo "pattern1 = $pattern1" # a*c (everything between 'a' and 'c')
echo "--------------"
echo '${var1#$pattern1} =' "${var1#$pattern1}" # d12345abc6789
# Shortest possible match, strips out first 3 characters abcd12345abc6789
# ^^^^^ |-|
echo '${var1##$pattern1} =' "${var1##$pattern1}" # 6789
# Longest possible match, strips out first 12 characters abcd12345abc6789
# ^^^^^ |----------|
echo; echo; echo
pattern2=b*9 # everything between 'b' and '9'
echo "var1 = $var1" # Still abcd12345abc6789
echo
echo "pattern2 = $pattern2"
echo "--------------"
echo '${var1%pattern2} =' "${var1%$pattern2}" # abcd12345a
# Shortest possible match, strips out last 6 characters abcd12345abc6789
# ^^^^ |----|
echo '${var1%%pattern2} =' "${var1%%$pattern2}" # a
# Longest possible match, strips out last 12 characters abcd12345abc6789
# ^^^^ |-------------|
# Remember, # and ## work from the left end (beginning) of string,
# % and %% work from the right end.
echo
exit 0
#!/bin/bash
# rfe.sh: Renaming file extensions.
#
# rfe old_extension new_extension
#
# Example:
# To rename all *.gif files in working directory to *.jpg,
# rfe gif jpg
E_BADARGS=65
case $# in
0|1) # The vertical bar means "or" in this context.
echo "Usage: `basename $0` old_file_suffix new_file_suffix"
exit $E_BADARGS # If 0 or 1 arg, then bail out.
;;
esac
for filename in *.$1
# Traverse list of files ending with 1st argument.
do
mv $filename ${filename%$1}$2
# Strip off part of filename matching 1st argument,
#+ then append 2nd argument.
done
exit 0
#!/bin/bash
var1=abcd-1234-defg
echo "var1 = $var1"
t=${var1#*-*}
echo "var1 (with everything, up to and including first - stripped out) = $t"
# t=${var1#*-} works just the same,
#+ since # matches the shortest string,
#+ and * matches everything preceding, including an empty string.
# (Thanks, Stephane Chazelas, for pointing this out.)
t=${var1##*-*}
echo "If var1 contains a \"-\", returns empty string... var1 = $t"
t=${var1%*-*}
echo "var1 (with everything from the last - on stripped out) = $t"
echo
# -------------------------------------------
path_name=/home/bozo/ideas/thoughts.for.today
# -------------------------------------------
echo "path_name = $path_name"
t=${path_name##/*/}
echo "path_name, stripped of prefixes = $t"
# Same effect as t=`basename $path_name` in this particular case.
# t=${path_name%/}; t=${t##*/} is a more general solution,
#+ but still fails sometimes.
# If $path_name ends with a newline, then `basename $path_name` will not work,
#+ but the above expression will.
# (Thanks, S.C.)
t=${path_name%/*.*}
# Same effect as t=`dirname $path_name`
echo "path_name, stripped of suffixes = $t"
# These will fail in some cases, such as "../", "/foo////", # "foo/", "/".
# Removing suffixes, especially when the basename has no suffix,
#+ but the dirname does, also complicates matters.
# (Thanks, S.C.)
echo
t=${path_name:11}
echo "$path_name, with first 11 chars stripped off = $t"
t=${path_name:11:5}
echo "$path_name, with first 11 chars stripped off, length 5 = $t"
echo
t=${path_name/bozo/clown}
echo "$path_name with \"bozo\" replaced by \"clown\" = $t"
t=${path_name/today/}
echo "$path_name with \"today\" deleted = $t"
t=${path_name//o/O}
echo "$path_name with all o's capitalized = $t"
t=${path_name//o/}
echo "$path_name with all o's deleted = $t"
exit 0
#!/bin/bash
# var-match.sh:
# Demo of pattern replacement at prefix / suffix of string.
v0=abc1234zip1234abc # Original variable.
echo "v0 = $v0" # abc1234zip1234abc
echo
# Match at prefix (beginning) of string.
v1=${v0/#abc/ABCDEF} # abc1234zip1234abc
# |-|
echo "v1 = $v1" # ABCDEF1234zip1234abc
# |----|
# Match at suffix (end) of string.
v2=${v0/%abc/ABCDEF} # abc1234zip123abc
# |-|
echo "v2 = $v2" # abc1234zip1234ABCDEF
# |----|
echo
# ----------------------------------------------------
# Must match at beginning / end of string,
#+ otherwise no replacement results.
# ----------------------------------------------------
v3=${v0/#123/000} # Matches, but not at beginning.
echo "v3 = $v3" # abc1234zip1234abc
# NO REPLACEMENT.
v4=${v0/%123/000} # Matches, but not at end.
echo "v4 = $v4" # abc1234zip1234abc
# NO REPLACEMENT.
exit 0
# This is a variation on indirect reference, but with a * or @.
# Bash, version 2.04, adds this feature.
xyz23=whatever
xyz24=
a=${!xyz*} # Expands to *names* of declared variables
# ^ ^ ^ + beginning with "xyz".
echo "a = $a" # a = xyz23 xyz24
a=${!xyz@} # Same as above.
echo "a = $a" # a = xyz23 xyz24
echo "---"
abc23=something_else
b=${!abc*}
echo "b = $b" # b = abc23
c=${!b} # Now, the more familiar type of indirect reference.
echo $c # something_else</pre>]
#!/bin/bash
area[11]=23
area[13]=37
area[51]=UFOs
# Array members need not be consecutive or contiguous.
# Some members of the array can be left uninitialized.
# Gaps in the array are okay.
# In fact, arrays with sparse data ("sparse arrays")
#+ are useful in spreadsheet-processing software.
echo -n "area[11] = "
echo ${area[11]} # {curly brackets} needed.
echo -n "area[13] = "
echo ${area[13]}
echo "Contents of area[51] are ${area[51]}."
# Contents of uninitialized array variable print blank (null variable).
echo -n "area[43] = "
echo ${area[43]}
echo "(area[43] unassigned)"
echo
# Sum of two array variables assigned to third
area[5]=`expr ${area[11]} + ${area[13]}`
echo "area[5] = area[11] + area[13]"
echo -n "area[5] = "
echo ${area[5]}
area[6]=`expr ${area[11]} + ${area[51]}`
echo "area[6] = area[11] + area[51]"
echo -n "area[6] = "
echo ${area[6]}
# This fails because adding an integer to a string is not permitted.
echo; echo; echo
# -----------------------------------------------------------------
# Another array, "area2".
# Another way of assigning array variables...
# array_name=( XXX YYY ZZZ ... )
area2=( zero one two three four )
echo -n "area2[0] = "
echo ${area2[0]}
# Aha, zero-based indexing (first element of array is [0], not [1]).
echo -n "area2[1] = "
echo ${area2[1]} # [1] is second element of array.
# -----------------------------------------------------------------
echo; echo; echo
# -----------------------------------------------
# Yet another array, "area3".
# Yet another way of assigning array variables...
# array_name=([xx]=XXX [yy]=YYY ...)
area3=([17]=seventeen [24]=twenty-four)
echo -n "area3[17] = "
echo ${area3[17]}
echo -n "area3[24] = "
echo ${area3[24]}
# -----------------------------------------------
exit 0
base64_charset=( {A..Z} {a..z} {0..9} + / = )
# Using extended brace expansion
#+ to initialize the elements of the array.
# Excerpted from vladz's "base64.sh" script
#+ in the "Contributed Scripts" appendix.
string=abcABC123ABCabc
echo ${string[@]} # abcABC123ABCabc
echo ${string[*]} # abcABC123ABCabc
echo ${string[0]} # abcABC123ABCabc
echo ${string[1]} # No output!
# Why?
echo ${#string[@]} # 1
# One element in the array.
# The string itself.
# Thank you, Michael Zick, for pointing this out.
#!/bin/bash
# poem.sh: Pretty-prints one of the ABS Guide author's favorite poems.
# Lines of the poem (single stanza).
Line[1]="I do not know which to prefer,"
Line[2]="The beauty of inflections"
Line[3]="Or the beauty of innuendoes,"
Line[4]="The blackbird whistling"
Line[5]="Or just after."
# Note that quoting permits embedding whitespace.
# Attribution.
Attrib[1]=" Wallace Stevens"
Attrib[2]="\"Thirteen Ways of Looking at a Blackbird\""
# This poem is in the Public Domain (copyright expired).
echo
tput bold # Bold print.
for index in 1 2 3 4 5 # Five lines.
do
printf " %s\n" "${Line[index]}"
done
for index in 1 2 # Two attribution lines.
do
printf " %s\n" "${Attrib[index]}"
done
tput sgr0 # Reset terminal.
# See 'tput' docs.
echo
exit 0
# Exercise:
# --------
# Modify this script to pretty-print a poem from a text data file.
#!/bin/bash
# array-ops.sh: More fun with arrays.
array=( zero one two three four five )
# Element 0 1 2 3 4 5
echo ${array[0]} # zero
echo ${array:0} # zero
# Parameter expansion of first element,
#+ starting at position # 0 (1st character).
echo ${array:1} # ero
# Parameter expansion of first element,
#+ starting at position # 1 (2nd character).
echo "--------------"
echo ${#array[0]} # 4
# Length of first element of array.
echo ${#array} # 4
# Length of first element of array.
# (Alternate notation)
echo ${#array[1]} # 3
# Length of second element of array.
# Arrays in Bash have zero-based indexing.
echo ${#array[*]} # 6
# Number of elements in array.
echo ${#array[@]} # 6
# Number of elements in array.
echo "--------------"
array2=( [0]="first element" [1]="second element" [3]="fourth element" )
# ^ ^ ^ ^ ^ ^ ^ ^ ^
# Quoting permits embedding whitespace within individual array elements.
echo ${array2[0]} # first element
echo ${array2[1]} # second element
echo ${array2[2]} #
# Skipped in initialization, and therefore null.
echo ${array2[3]} # fourth element
echo ${#array2[0]} # 13 (length of first element)
echo ${#array2[*]} # 3 (number of elements in array)
exit
#!/bin/bash
# array-strops.sh: String operations on arrays.
# Script by Michael Zick.
# Used in ABS Guide with permission.
# Fixups: 05 May 08, 04 Aug 08.
# In general, any string operation using the ${name ... } notation
#+ can be applied to all string elements in an array,
#+ with the ${name[@] ... } or ${name[*] ...} notation.
arrayZ=( one two three four five five )
echo
# Trailing Substring Extraction
echo ${arrayZ[@]:0} # one two three four five five
# ^ All elements.
echo ${arrayZ[@]:1} # two three four five five
# ^ All elements following element[0].
echo ${arrayZ[@]:1:2} # two three
# ^ Only the two elements after element[0].
echo "---------"
# Substring Removal
# Removes shortest match from front of string(s).
echo ${arrayZ[@]#f*r} # one two three five five
# ^ # Applied to all elements of the array.
# Matches "four" and removes it.
# Longest match from front of string(s)
echo ${arrayZ[@]##t*e} # one two four five five
# ^^ # Applied to all elements of the array.
# Matches "three" and removes it.
# Shortest match from back of string(s)
echo ${arrayZ[@]%h*e} # one two t four five five
# ^ # Applied to all elements of the array.
# Matches "hree" and removes it.
# Longest match from back of string(s)
echo ${arrayZ[@]%%t*e} # one two four five five
# ^^ # Applied to all elements of the array.
# Matches "three" and removes it.
echo "----------------------"
# Substring Replacement
# Replace first occurrence of substring with replacement.
echo ${arrayZ[@]/fiv/XYZ} # one two three four XYZe XYZe
# ^ # Applied to all elements of the array.
# Replace all occurrences of substring.
echo ${arrayZ[@]//iv/YY} # one two three four fYYe fYYe
# Applied to all elements of the array.
# Delete all occurrences of substring.
# Not specifing a replacement defaults to 'delete' ...
echo ${arrayZ[@]//fi/} # one two three four ve ve
# ^^ # Applied to all elements of the array.
# Replace front-end occurrences of substring.
echo ${arrayZ[@]/#fi/XY} # one two three four XYve XYve
# ^ # Applied to all elements of the array.
# Replace back-end occurrences of substring.
echo ${arrayZ[@]/%ve/ZZ} # one two three four fiZZ fiZZ
# ^ # Applied to all elements of the array.
echo ${arrayZ[@]/%o/XX} # one twXX three four five five
# ^ # Why?
echo "-----------------------------"
replacement() {
echo -n "!!!"
}
echo ${arrayZ[@]/%e/$(replacement)}
# ^ ^^^^^^^^^^^^^^
# on!!! two thre!!! four fiv!!! fiv!!!
# The stdout of replacement() is the replacement string.
# Q.E.D: The replacement action is, in effect, an 'assignment.'
echo "------------------------------------"
# Accessing the "for-each":
echo ${arrayZ[@]//*/$(replacement optional_arguments)}
# ^^ ^^^^^^^^^^^^^
# !!! !!! !!! !!! !!! !!!
# Now, if Bash would only pass the matched string
#+ to the function being called . . .
echo
exit 0
# Before reaching for a Big Hammer -- Perl, Python, or all the rest --
# recall:
# $( ... ) is command substitution.
# A function runs as a sub-process.
# A function writes its output (if echo-ed) to stdout.
# Assignment, in conjunction with "echo" and command substitution,
#+ can read a function's stdout.
# The name[@] notation specifies (the equivalent of) a "for-each"
#+ operation.
# Bash is more powerful than you think!
#!/bin/bash
# script-array.sh: Loads this script into an array.
# Inspired by an e-mail from Chris Martin (thanks!).
script_contents=( $(cat "$0") ) # Stores contents of this script ($0)
#+ in an array.
for element in $(seq 0 $((${#script_contents[@]} - 1)))
do # ${#script_contents[@]}
#+ gives number of elements in the array.
#
# Question:
# Why is seq 0 necessary?
# Try changing it to seq 1.
echo -n "${script_contents[$element]}"
# List each field of this script on a single line.
# echo -n "${script_contents[element]}" also works because of ${ ... }.
echo -n " -- " # Use " -- " as a field separator.
done
echo
exit 0
# Exercise:
# --------
# Modify this script so it lists itself
#+ in its original format,
#+ complete with whitespace, line breaks, etc.
#!/bin/bash
declare -a colors
# All subsequent commands in this script will treat
#+ the variable "colors" as an array.
echo "Enter your favorite colors (separated from each other by a space)."
read -a colors # Enter at least 3 colors to demonstrate features below.
# Special option to 'read' command,
#+ allowing assignment of elements in an array.
echo
element_count=${#colors[@]}
# Special syntax to extract number of elements in array.
# element_count=${#colors[*]} works also.
#
# The "@" variable allows word splitting within quotes
#+ (extracts variables separated by whitespace).
#
# This corresponds to the behavior of "$@" and "$*"
#+ in positional parameters.
index=0
while [ "$index" -lt "$element_count" ]
do # List all the elements in the array.
echo ${colors[$index]}
# ${colors[index]} also works because it's within ${ ... } brackets.
let "index = $index + 1"
# Or:
# ((index++))
done
# Each array element listed on a separate line.
# If this is not desired, use echo -n "${colors[$index]} "
#
# Doing it with a "for" loop instead:
# for i in "${colors[@]}"
# do
# echo "$i"
# done
# (Thanks, S.C.)
echo
# Again, list all the elements in the array, but using a more elegant method.
echo ${colors[@]} # echo ${colors[*]} also works.
echo
# The "unset" command deletes elements of an array, or entire array.
unset colors[1] # Remove 2nd element of array.
# Same effect as colors[1]=
echo ${colors[@]} # List array again, missing 2nd element.
unset colors # Delete entire array.
# unset colors[*] and
#+ unset colors[@] also work.
echo; echo -n "Colors gone."
echo ${colors[@]} # List array again, now empty.
exit 0
#!/bin/bash
# empty-array.sh
# Thanks to Stephane Chazelas for the original example,
#+ and to Michael Zick and Omair Eshkenazi, for extending it.
# And to Nathan Coulter for clarifications and corrections.
# An empty array is not the same as an array with empty elements.
array0=( first second third )
array1=( '' ) # "array1" consists of one empty element.
array2=( ) # No elements . . . "array2" is empty.
array3=( ) # What about this array?
echo
ListArray()
{
echo
echo "Elements in array0: ${array0[@]}"
echo "Elements in array1: ${array1[@]}"
echo "Elements in array2: ${array2[@]}"
echo "Elements in array3: ${array3[@]}"
echo
echo "Length of first element in array0 = ${#array0}"
echo "Length of first element in array1 = ${#array1}"
echo "Length of first element in array2 = ${#array2}"
echo "Length of first element in array3 = ${#array3}"
echo
echo "Number of elements in array0 = ${#array0[*]}" # 3
echo "Number of elements in array1 = ${#array1[*]}" # 1 (Surprise!)
echo "Number of elements in array2 = ${#array2[*]}" # 0
echo "Number of elements in array3 = ${#array3[*]}" # 0
}
# ===================================================================
ListArray
# Try extending those arrays.
# Adding an element to an array.
array0=( "${array0[@]}" "new1" )
array1=( "${array1[@]}" "new1" )
array2=( "${array2[@]}" "new1" )
array3=( "${array3[@]}" "new1" )
ListArray
# or
array0[${#array0[*]}]="new2"
array1[${#array1[*]}]="new2"
array2[${#array2[*]}]="new2"
array3[${#array3[*]}]="new2"
ListArray
# When extended as above, arrays are 'stacks' ...
# Above is the 'push' ...
# The stack 'height' is:
height=${#array2[@]}
echo
echo "Stack height for array2 = $height"
# The 'pop' is:
unset array2[${#array2[@]}-1] # Arrays are zero-based,
height=${#array2[@]} #+ which means first element has index 0.
echo
echo "POP"
echo "New stack height for array2 = $height"
ListArray
# List only 2nd and 3rd elements of array0.
from=1 # Zero-based numbering.
to=2
array3=( ${array0[@]:1:2} )
echo
echo "Elements in array3: ${array3[@]}"
# Works like a string (array of characters).
# Try some other "string" forms.
# Replacement:
array4=( ${array0[@]/second/2nd} )
echo
echo "Elements in array4: ${array4[@]}"
# Replace all matching wildcarded string.
array5=( ${array0[@]//new?/old} )
echo
echo "Elements in array5: ${array5[@]}"
# Just when you are getting the feel for this . . .
array6=( ${array0[@]#*new} )
echo # This one might surprise you.
echo "Elements in array6: ${array6[@]}"
array7=( ${array0[@]#new1} )
echo # After array6 this should not be a surprise.
echo "Elements in array7: ${array7[@]}"
# Which looks a lot like . . .
array8=( ${array0[@]/new1/} )
echo
echo "Elements in array8: ${array8[@]}"
# So what can one say about this?
# The string operations are performed on
#+ each of the elements in var[@] in succession.
# Therefore : Bash supports string vector operations.
# If the result is a zero length string,
#+ that element disappears in the resulting assignment.
# However, if the expansion is in quotes, the null elements remain.
# Michael Zick: Question, are those strings hard or soft quotes?
# Nathan Coulter: There is no such thing as "soft quotes."
#! What's really happening is that
#!+ the pattern matching happens after
#!+ all the other expansions of [word]
#!+ in cases like ${parameter#word}.
zap='new*'
array9=( ${array0[@]/$zap/} )
echo
echo "Number of elements in array9: ${#array9[@]}"
array9=( "${array0[@]/$zap/}" )
echo "Elements in array9: ${array9[@]}"
# This time the null elements remain.
echo "Number of elements in array9: ${#array9[@]}"
# Just when you thought you were still in Kansas . . .
array10=( ${array0[@]#$zap} )
echo
echo "Elements in array10: ${array10[@]}"
# But, the asterisk in zap won't be interpreted if quoted.
array10=( ${array0[@]#"$zap"} )
echo
echo "Elements in array10: ${array10[@]}"
# Well, maybe we _are_ still in Kansas . . .
# (Revisions to above code block by Nathan Coulter.)
# Compare array7 with array10.
# Compare array8 with array9.
# Reiterating: No such thing as soft quotes!
# Nathan Coulter explains:
# Pattern matching of 'word' in ${parameter#word} is done after
#+ parameter expansion and *before* quote removal.
# In the normal case, pattern matching is done *after* quote removal.
exit
# Copying an array.
array2=( "${array1[@]}" )
# or
array2="${array1[@]}"
#
# However, this fails with "sparse" arrays,
#+ arrays with holes (missing elements) in them,
#+ as Jochen DeSmet points out.
# ------------------------------------------
array1[0]=0
# array1[1] not assigned
array1[2]=2
array2=( "${array1[@]}" ) # Copy it?
echo ${array2[0]} # 0
echo ${array2[2]} # (null), should be 2
# ------------------------------------------
# Adding an element to an array.
array=( "${array[@]}" "new element" )
# or
array[${#array[*]}]="new element"
# Thanks, S.C.
#!/bin/bash
filename=sample_file
# cat sample_file
#
# 1 a b c
# 2 d e fg
declare -a array1
array1=( `cat "$filename"`) # Loads contents
# List file to stdout #+ of $filename into array1.
#
# array1=( `cat "$filename" | tr '\n' ' '`)
# change linefeeds in file to spaces.
# Not necessary because Bash does word splitting,
#+ changing linefeeds to spaces.
echo ${array1[@]} # List the array.
# 1 a b c 2 d e fg
#
# Each whitespace-separated "word" in the file
#+ has been assigned to an element of the array.
element_count=${#array1[*]}
echo $element_count # 8
#! /bin/bash
# array-assign.bash
# Array operations are Bash-specific,
#+ hence the ".bash" in the script name.
# Copyright (c) Michael S. Zick, 2003, All rights reserved.
# License: Unrestricted reuse in any form, for any purpose.
# Version: $ID$
#
# Clarification and additional comments by William Park.
# Based on an example provided by Stephane Chazelas
#+ which appeared in an earlier version of the
#+ Advanced Bash Scripting Guide.
# Output format of the 'times' command:
# User CPU <space&gt; System CPU
# User CPU of dead children <space&gt; System CPU of dead children
# Bash has two versions of assigning all elements of an array
#+ to a new array variable.
# Both drop 'null reference' elements
#+ in Bash versions 2.04 and later.
# An additional array assignment that maintains the relationship of
#+ [subscript]=value for arrays may be added to newer versions.
# Constructs a large array using an internal command,
#+ but anything creating an array of several thousand elements
#+ will do just fine.
declare -a bigOne=( /dev/* ) # All the files in /dev . . .
echo
echo 'Conditions: Unquoted, default IFS, All-Elements-Of'
echo "Number of elements in array is ${#bigOne[@]}"
# set -vx
echo
echo '- - testing: =( ${array[@]} ) - -'
times
declare -a bigTwo=( ${bigOne[@]} )
# Note parens: ^ ^
times
echo
echo '- - testing: =${array[@]} - -'
times
declare -a bigThree=${bigOne[@]}
# No parentheses this time.
times
# Comparing the numbers shows that the second form, pointed out
#+ by Stephane Chazelas, is faster.
#
# As William Park explains:
#+ The bigTwo array assigned element by element (because of parentheses),
#+ whereas bigThree assigned as a single string.
# So, in essence, you have:
# bigTwo=( [0]="..." [1]="..." [2]="..." ... )
# bigThree=( [0]="... ... ..." )
#
# Verify this by: echo ${bigTwo[0]}
# echo ${bigThree[0]}
# I will continue to use the first form in my example descriptions
#+ because I think it is a better illustration of what is happening.
# The reusable portions of my examples will actual contain
#+ the second form where appropriate because of the speedup.
# MSZ: Sorry about that earlier oversight folks.
# Note:
# ----
# The "declare -a" statements in lines 32 and 44
#+ are not strictly necessary, since it is implicit
#+ in the Array=( ... ) assignment form.
# However, eliminating these declarations slows down
#+ the execution of the following sections of the script.
# Try it, and see.
exit 0
#! /bin/bash
# CopyArray.sh
#
# This script written by Michael Zick.
# Used here with permission.
# How-To "Pass by Name & Return by Name"
#+ or "Building your own assignment statement".
CpArray_Mac() {
# Assignment Command Statement Builder
echo -n 'eval '
echo -n "$2" # Destination name
echo -n '=( ${'
echo -n "$1" # Source name
echo -n '[@]} )'
# That could all be a single command.
# Matter of style only.
}
declare -f CopyArray # Function "Pointer"
CopyArray=CpArray_Mac # Statement Builder
Hype()
{
# Hype the array named $1.
# (Splice it together with array containing "Really Rocks".)
# Return in array named $2.
local -a TMP
local -a hype=( Really Rocks )
$($CopyArray $1 TMP)
TMP=( ${TMP[@]} ${hype[@]} )
$($CopyArray TMP $2)
}
declare -a before=( Advanced Bash Scripting )
declare -a after
echo "Array Before = ${before[@]}"
Hype before after
echo "Array After = ${after[@]}"
# Too much hype?
echo "What ${after[@]:3:2}?"
declare -a modest=( ${after[@]:2:1} ${after[@]:3:2} )
# ---- substring extraction ----
echo "Array Modest = ${modest[@]}"
# What happened to 'before' ?
echo "Array Before = ${before[@]}"
exit 0
#! /bin/bash
# array-append.bash
# Copyright (c) Michael S. Zick, 2003, All rights reserved.
# License: Unrestricted reuse in any form, for any purpose.
# Version: $ID$
#
# Slightly modified in formatting by M.C.
# Array operations are Bash-specific.
# Legacy UNIX /bin/sh lacks equivalents.
# Pipe the output of this script to 'more'
#+ so it doesn't scroll off the terminal.
# Or, redirect output to a file.
declare -a array1=( zero1 one1 two1 )
# Subscript packed.
declare -a array2=( [0]=zero2 [2]=two2 [3]=three2 )
# Subscript sparse -- [1] is not defined.
echo
echo '- Confirm that the array is really subscript sparse. -'
echo "Number of elements: 4" # Hard-coded for illustration.
for (( i = 0 ; i < 4 ; i++ ))
do
echo "Element [$i]: ${array2[$i]}"
done
# See also the more general code example in basics-reviewed.bash.
declare -a dest
# Combine (append) two arrays into a third array.
echo
echo 'Conditions: Unquoted, default IFS, All-Elements-Of operator'
echo '- Undefined elements not present, subscripts not maintained. -'
# # The undefined elements do not exist; they are not being dropped.
dest=( ${array1[@]} ${array2[@]} )
# dest=${array1[@]}${array2[@]} # Strange results, possibly a bug.
# Now, list the result.
echo
echo '- - Testing Array Append - -'
cnt=${#dest[@]}
echo "Number of elements: $cnt"
for (( i = 0 ; i < cnt ; i++ ))
do
echo "Element [$i]: ${dest[$i]}"
done
# Assign an array to a single array element (twice).
dest[0]=${array1[@]}
dest[1]=${array2[@]}
# List the result.
echo
echo '- - Testing modified array - -'
cnt=${#dest[@]}
echo "Number of elements: $cnt"
for (( i = 0 ; i < cnt ; i++ ))
do
echo "Element [$i]: ${dest[$i]}"
done
# Examine the modified second element.
echo
echo '- - Reassign and list second element - -'
declare -a subArray=${dest[1]}
cnt=${#subArray[@]}
echo "Number of elements: $cnt"
for (( i = 0 ; i < cnt ; i++ ))
do
echo "Element [$i]: ${subArray[$i]}"
done
# The assignment of an entire array to a single element
#+ of another array using the '=${ ... }' array assignment
#+ has converted the array being assigned into a string,
#+ with the elements separated by a space (the first character of IFS).
# If the original elements didn't contain whitespace . . .
# If the original array isn't subscript sparse . . .
# Then we could get the original array structure back again.
# Restore from the modified second element.
echo
echo '- - Listing restored element - -'
declare -a subArray=( ${dest[1]} )
cnt=${#subArray[@]}
echo "Number of elements: $cnt"
for (( i = 0 ; i < cnt ; i++ ))
do
echo "Element [$i]: ${subArray[$i]}"
done
echo '- - Do not depend on this behavior. - -'
echo '- - This behavior is subject to change - -'
echo '- - in versions of Bash newer than version 2.05b - -'
# MSZ: Sorry about any earlier confusion folks.
exit 0
#!/bin/bash
# bubble.sh: Bubble sort, of sorts.
# Recall the algorithm for a bubble sort. In this particular version...
# With each successive pass through the array to be sorted,
#+ compare two adjacent elements, and swap them if out of order.
# At the end of the first pass, the "heaviest" element has sunk to bottom.
# At the end of the second pass, the next "heaviest" one has sunk next to bottom.
# And so forth.
# This means that each successive pass needs to traverse less of the array.
# You will therefore notice a speeding up in the printing of the later passes.
exchange()
{
# Swaps two members of the array.
local temp=${Countries[$1]} # Temporary storage
#+ for element getting swapped out.
Countries[$1]=${Countries[$2]}
Countries[$2]=$temp
return
}
declare -a Countries # Declare array,
#+ optional here since it's initialized below.
# Is it permissable to split an array variable over multiple lines
#+ using an escape (\)?
# Yes.
Countries=(Netherlands Ukraine Zaire Turkey Russia Yemen Syria \
Brazil Argentina Nicaragua Japan Mexico Venezuela Greece England \
Israel Peru Canada Oman Denmark Wales France Kenya \
Xanadu Qatar Liechtenstein Hungary)
# "Xanadu" is the mythical place where, according to Coleridge,
#+ Kubla Khan did a pleasure dome decree.
clear # Clear the screen to start with.
echo "0: ${Countries[*]}" # List entire array at pass 0.
number_of_elements=${#Countries[@]}
let "comparisons = $number_of_elements - 1"
count=1 # Pass number.
while [ "$comparisons" -gt 0 ] # Beginning of outer loop
do
index=0 # Reset index to start of array after each pass.
while [ "$index" -lt "$comparisons" ] # Beginning of inner loop
do
if [ ${Countries[$index]} \&gt; ${Countries[`expr $index + 1`]} ]
# If out of order...
# Recalling that \&gt; is ASCII comparison operator
#+ within single brackets.
# if [[ ${Countries[$index]} &gt; ${Countries[`expr $index + 1`]} ]]
#+ also works.
then
exchange $index `expr $index + 1` # Swap.
fi
let "index += 1" # Or, index+=1 on Bash, ver. 3.1 or newer.
done # End of inner loop
# ----------------------------------------------------------------------
# Paulo Marcel Coelho Aragao suggests for-loops as a simpler altenative.
#
# for (( last = $number_of_elements - 1 ; last &gt; 0 ; last-- ))
## Fix by C.Y. Hunt ^ (Thanks!)
# do
# for (( i = 0 ; i < last ; i++ ))
# do
# [[ "${Countries[$i]}" &gt; "${Countries[$((i+1))]}" ]] \
# && exchange $i $((i+1))
# done
# done
# ----------------------------------------------------------------------
let "comparisons -= 1" # Since "heaviest" element bubbles to bottom,
#+ we need do one less comparison each pass.
echo
echo "$count: ${Countries[@]}" # Print resultant array at end of each pass.
echo
let "count += 1" # Increment pass count.
done # End of outer loop
# All done.
exit 0
#!/bin/bash
# "Nested" array.
# Michael Zick provided this example,
#+ with corrections and clarifications by William Park.
AnArray=( $(ls --inode --ignore-backups --almost-all \
--directory --full-time --color=none --time=status \
--sort=time -l ${PWD} ) ) # Commands and options.
# Spaces are significant . . . and don't quote anything in the above.
SubArray=( ${AnArray[@]:11:1} ${AnArray[@]:6:5} )
# This array has six elements:
#+ SubArray=( [0]=${AnArray[11]} [1]=${AnArray[6]} [2]=${AnArray[7]}
# [3]=${AnArray[8]} [4]=${AnArray[9]} [5]=${AnArray[10]} )
#
# Arrays in Bash are (circularly) linked lists
#+ of type string (char *).
# So, this isn't actually a nested array,
#+ but it's functionally similar.
echo "Current directory and date of last status change:"
echo "${SubArray[@]}"
exit 0
#!/bin/bash
# embedded-arrays.sh
# Embedded arrays and indirect references.
# This script by Dennis Leeuw.
# Used with permission.
# Modified by document author.
ARRAY1=(
VAR1_1=value11
VAR1_2=value12
VAR1_3=value13
)
ARRAY2=(
VARIABLE="test"
STRING="VAR1=value1 VAR2=value2 VAR3=value3"
ARRAY21=${ARRAY1[*]}
) # Embed ARRAY1 within this second array.
function print () {
OLD_IFS="$IFS"
IFS=$'\n' # To print each array element
#+ on a separate line.
TEST1="ARRAY2[*]"
local ${!TEST1} # See what happens if you delete this line.
# Indirect reference.
# This makes the components of $TEST1
#+ accessible to this function.
# Let's see what we've got so far.
echo
echo "\$TEST1 = $TEST1" # Just the name of the variable.
echo; echo
echo "{\$TEST1} = ${!TEST1}" # Contents of the variable.
# That's what an indirect
#+ reference does.
echo
echo "-------------------------------------------"; echo
echo
# Print variable
echo "Variable VARIABLE: $VARIABLE"
# Print a string element
IFS="$OLD_IFS"
TEST2="STRING[*]"
local ${!TEST2} # Indirect reference (as above).
echo "String element VAR2: $VAR2 from STRING"
# Print an array element
TEST2="ARRAY21[*]"
local ${!TEST2} # Indirect reference (as above).
echo "Array element VAR1_1: $VAR1_1 from ARRAY21"
}
print
echo
exit 0
# As the author of the script notes,
#+ "you can easily expand it to create named-hashes in bash."
# (Difficult) exercise for the reader: implement this.
#!/bin/bash
# sieve.sh (ex68.sh)
# Sieve of Eratosthenes
# Ancient algorithm for finding prime numbers.
# This runs a couple of orders of magnitude slower
#+ than the equivalent program written in C.
LOWER_LIMIT=1 # Starting with 1.
UPPER_LIMIT=1000 # Up to 1000.
# (You may set this higher . . . if you have time on your hands.)
PRIME=1
NON_PRIME=0
let SPLIT=UPPER_LIMIT/2
# Optimization:
# Need to test numbers only halfway to upper limit. Why?
declare -a Primes
# Primes[] is an array.
initialize ()
{
# Initialize the array.
i=$LOWER_LIMIT
until [ "$i" -gt "$UPPER_LIMIT" ]
do
Primes[i]=$PRIME
let "i += 1"
done
# Assume all array members guilty (prime)
#+ until proven innocent.
}
print_primes ()
{
# Print out the members of the Primes[] array tagged as prime.
i=$LOWER_LIMIT
until [ "$i" -gt "$UPPER_LIMIT" ]
do
if [ "${Primes[i]}" -eq "$PRIME" ]
then
printf "%8d" $i
# 8 spaces per number gives nice, even columns.
fi
let "i += 1"
done
}
sift () # Sift out the non-primes.
{
let i=$LOWER_LIMIT+1
# Let's start with 2.
until [ "$i" -gt "$UPPER_LIMIT" ]
do
if [ "${Primes[i]}" -eq "$PRIME" ]
# Don't bother sieving numbers already sieved (tagged as non-prime).
then
t=$i
while [ "$t" -le "$UPPER_LIMIT" ]
do
let "t += $i "
Primes[t]=$NON_PRIME
# Tag as non-prime all multiples.
done
fi
let "i += 1"
done
}
# ==============================================
# main ()
# Invoke the functions sequentially.
initialize
sift
print_primes
# This is what they call structured programming.
# ==============================================
echo
exit 0
# -------------------------------------------------------- #
# Code below line will not execute, because of 'exit.'
# This improved version of the Sieve, by Stephane Chazelas,
#+ executes somewhat faster.
# Must invoke with command-line argument (limit of primes).
UPPER_LIMIT=$1 # From command-line.
let SPLIT=UPPER_LIMIT/2 # Halfway to max number.
Primes=( '' $(seq $UPPER_LIMIT) )
i=1
until (( ( i += 1 ) &gt; SPLIT )) # Need check only halfway.
do
if [[ -n ${Primes[i]} ]]
then
t=$i
until (( ( t += i ) &gt; UPPER_LIMIT ))
do
Primes[t]=
done
fi
done
echo ${Primes[*]}
exit $?
#!/bin/bash
# Optimized Sieve of Eratosthenes
# Script by Jared Martin, with very minor changes by ABS Guide author.
# Used in ABS Guide with permission (thanks!).
# Based on script in Advanced Bash Scripting Guide.
# http://tldp.org/LDP/abs/html/arrays.html#PRIMES0 (ex68.sh).
# http://www.cs.hmc.edu/~oneill/papers/Sieve-JFP.pdf (reference)
# Check results against http://primes.utm.edu/lists/small/1000.txt
# Necessary but not sufficient would be, e.g.,
# (($(sieve 7919 | wc -w) == 1000)) && echo "7919 is the 1000th prime"
UPPER_LIMIT=${1:?"Need an upper limit of primes to search."}
Primes=( '' $(seq ${UPPER_LIMIT}) )
typeset -i i t
Primes[i=1]='' # 1 is not a prime.
until (( ( i += 1 ) &gt; (${UPPER_LIMIT}/i) )) # Need check only ith-way.
do # Why?
if ((${Primes[t=i*(i-1), i]}))
# Obscure, but instructive, use of arithmetic expansion in subscript.
then
until (( ( t += i ) &gt; ${UPPER_LIMIT} ))
do Primes[t]=; done
fi
done
# echo ${Primes[*]}
echo # Change to original script for pretty-printing (80-col. display).
printf "%8d" ${Primes[*]}
echo; echo
exit $?
#!/bin/bash
# stack.sh: push-down stack simulation
# Similar to the CPU stack, a push-down stack stores data items
#+ sequentially, but releases them in reverse order, last-in first-out.
BP=100 # Base Pointer of stack array.
# Begin at element 100.
SP=$BP # Stack Pointer.
# Initialize it to "base" (bottom) of stack.
Data= # Contents of stack location.
# Must use global variable,
#+ because of limitation on function return range.
# 100 Base pointer <-- Base Pointer
# 99 First data item
# 98 Second data item
# ... More data
# Last data item <-- Stack pointer
declare -a stack
push() # Push item on stack.
{
if [ -z "$1" ] # Nothing to push?
then
return
fi
let "SP -= 1" # Bump stack pointer.
stack[$SP]=$1
return
}
pop() # Pop item off stack.
{
Data= # Empty out data item.
if [ "$SP" -eq "$BP" ] # Stack empty?
then
return
fi # This also keeps SP from getting past 100,
#+ i.e., prevents a runaway stack.
Data=${stack[$SP]}
let "SP += 1" # Bump stack pointer.
return
}
status_report() # Find out what's happening.
{
echo "-------------------------------------"
echo "REPORT"
echo "Stack Pointer = $SP"
echo "Just popped \""$Data"\" off the stack."
echo "-------------------------------------"
echo
}
# =======================================================
# Now, for some fun.
echo
# See if you can pop anything off empty stack.
pop
status_report
echo
push garbage
pop
status_report # Garbage in, garbage out.
value1=23; push $value1
value2=skidoo; push $value2
value3=LAST; push $value3
pop # LAST
status_report
pop # skidoo
status_report
pop # 23
status_report # Last-in, first-out!
# Notice how the stack pointer decrements with each push,
#+ and increments with each pop.
echo
exit 0
# =======================================================
# Exercises:
# ---------
# 1) Modify the "push()" function to permit pushing
# + multiple element on the stack with a single function call.
# 2) Modify the "pop()" function to permit popping
# + multiple element from the stack with a single function call.
# 3) Add error checking to the critical functions.
# That is, return an error code, depending on
# + successful or unsuccessful completion of the operation,
# + and take appropriate action.
# 4) Using this script as a starting point,
# + write a stack-based 4-function calculator.
#!/bin/bash
# Douglas Hofstadter's notorious "Q-series":
# Q(1) = Q(2) = 1
# Q(n) = Q(n - Q(n-1)) + Q(n - Q(n-2)), for n&gt;2
# This is a "chaotic" integer series with strange
#+ and unpredictable behavior.
# The first 20 terms of the series are:
# 1 1 2 3 3 4 5 5 6 6 6 8 8 8 10 9 10 11 11 12
# See Hofstadter's book, _Goedel, Escher, Bach: An Eternal Golden Braid_,
#+ p. 137, ff.
LIMIT=100 # Number of terms to calculate.
LINEWIDTH=20 # Number of terms printed per line.
Q[1]=1 # First two terms of series are 1.
Q[2]=1
echo
echo "Q-series [$LIMIT terms]:"
echo -n "${Q[1]} " # Output first two terms.
echo -n "${Q[2]} "
for ((n=3; n <= $LIMIT; n++)) # C-like loop expression.
do # Q[n] = Q[n - Q[n-1]] + Q[n - Q[n-2]] for n&gt;2
# Need to break the expression into intermediate terms,
#+ since Bash doesn't handle complex array arithmetic very well.
let "n1 = $n - 1" # n-1
let "n2 = $n - 2" # n-2
t0=`expr $n - ${Q[n1]}` # n - Q[n-1]
t1=`expr $n - ${Q[n2]}` # n - Q[n-2]
T0=${Q[t0]} # Q[n - Q[n-1]]
T1=${Q[t1]} # Q[n - Q[n-2]]
Q[n]=`expr $T0 + $T1` # Q[n - Q[n-1]] + Q[n - Q[n-2]]
echo -n "${Q[n]} "
if [ `expr $n % $LINEWIDTH` -eq 0 ] # Format output.
then # ^ modulo
echo # Break lines into neat chunks.
fi
done
echo
exit 0
# This is an iterative implementation of the Q-series.
# The more intuitive recursive implementation is left as an exercise.
# Warning: calculating this series recursively takes a VERY long time
#+ via a script. C/C++ would be orders of magnitude faster.
#!/bin/bash
# twodim.sh: Simulating a two-dimensional array.
# A one-dimensional array consists of a single row.
# A two-dimensional array stores rows sequentially.
Rows=5
Columns=5
# 5 X 5 Array.
declare -a alpha # char alpha [Rows] [Columns];
# Unnecessary declaration. Why?
load_alpha ()
{
local rc=0
local index
for i in A B C D E F G H I J K L M N O P Q R S T U V W X Y
do # Use different symbols if you like.
local row=`expr $rc / $Columns`
local column=`expr $rc % $Rows`
let "index = $row * $Rows + $column"
alpha[$index]=$i
# alpha[$row][$column]
let "rc += 1"
done
# Simpler would be
#+ declare -a alpha=( A B C D E F G H I J K L M N O P Q R S T U V W X Y )
#+ but this somehow lacks the "flavor" of a two-dimensional array.
}
print_alpha ()
{
local row=0
local index
echo
while [ "$row" -lt "$Rows" ] # Print out in "row major" order:
do #+ columns vary,
#+ while row (outer loop) remains the same.
local column=0
echo -n " " # Lines up "square" array with rotated one.
while [ "$column" -lt "$Columns" ]
do
let "index = $row * $Rows + $column"
echo -n "${alpha[index]} " # alpha[$row][$column]
let "column += 1"
done
let "row += 1"
echo
done
# The simpler equivalent is
# echo ${alpha[*]} | xargs -n $Columns
echo
}
filter () # Filter out negative array indices.
{
echo -n " " # Provides the tilt.
# Explain how.
if [[ "$1" -ge 0 && "$1" -lt "$Rows" && "$2" -ge 0 && "$2" -lt "$Columns" ]]
then
let "index = $1 * $Rows + $2"
# Now, print it rotated.
echo -n " ${alpha[index]}"
# alpha[$row][$column]
fi
}
rotate () # Rotate the array 45 degrees --
{ #+ "balance" it on its lower lefthand corner.
local row
local column
for (( row = Rows; row &gt; -Rows; row-- ))
do # Step through the array backwards. Why?
for (( column = 0; column < Columns; column++ ))
do
if [ "$row" -ge 0 ]
then
let "t1 = $column - $row"
let "t2 = $column"
else
let "t1 = $column"
let "t2 = $column + $row"
fi
filter $t1 $t2 # Filter out negative array indices.
# What happens if you don't do this?
done
echo; echo
done
# Array rotation inspired by examples (pp. 143-146) in
#+ "Advanced C Programming on the IBM PC," by Herbert Mayer
#+ (see bibliography).
# This just goes to show that much of what can be done in C
#+ can also be done in shell scripting.
}
#--------------- Now, let the show begin. ------------#
load_alpha # Load the array.
print_alpha # Print it out.
rotate # Rotate it 45 degrees counterclockwise.
#-----------------------------------------------------#
exit 0
# This is a rather contrived, not to mention inelegant simulation.
# Exercises:
# ---------
# 1) Rewrite the array loading and printing functions
# in a more intuitive and less kludgy fashion.
#
# 2) Figure out how the array rotation functions work.
# Hint: think about the implications of backwards-indexing an array.
#
# 3) Rewrite this script to handle a non-square array,
# such as a 6 X 4 one.
# Try to minimize "distortion" when the array is rotated.</pre>]
#!/bin/bash
# ascii.sh
# ver. 0.2, reldate 26 Aug 2008
# Patched by ABS Guide author.
# Original script by Sebastian Arming.
# Used with permission (thanks!).
exec &gt;ASCII.txt # Save stdout to file,
#+ as in the example scripts
#+ reassign-stdout.sh and upperconv.sh.
MAXNUM=256
COLUMNS=5
OCT=8
OCTSQU=64
LITTLESPACE=-3
BIGSPACE=-5
i=1 # Decimal counter
o=1 # Octal counter
while [ "$i" -lt "$MAXNUM" ]; do # We don't have to count past 400 octal.
paddi=" $i"
echo -n "${paddi: $BIGSPACE} " # Column spacing.
paddo="00$o"
# echo -ne "\\${paddo: $LITTLESPACE}" # Original.
echo -ne "\\0${paddo: $LITTLESPACE}" # Fixup.
# ^
echo -n " "
if (( i % $COLUMNS == 0)); then # New line.
echo
fi
((i++, o++))
# The octal notation for 8 is 10, and 64 decimal is 100 octal.
(( i % $OCT == 0)) && ((o+=2))
(( i % $OCTSQU == 0)) && ((o+=20))
done
exit $?
# Compare this script with the "pr-asc.sh" example.
# This one handles "unprintable" characters.
# Exercise:
# Rewrite this script to use decimal numbers, rather than octal.
#!/bin/bash
# Script author: Joseph Steinhauser
# Lightly edited by ABS Guide author, but not commented.
# Used in ABS Guide with permission.
#-------------------------------------------------------------------------
#-- File: ascii.sh Print ASCII chart, base 10/8/16 (JETS-2012)
#-------------------------------------------------------------------------
#-- Usage: ascii [oct|dec|hex|help|8|10|16]
#--
#-- This script prints out a summary of ASCII char codes from Zero to 127.
#-- Numeric values may be printed in Base10, Octal, or Hex.
#--
#-- Format Based on: /usr/share/lib/pub/ascii with base-10 as default.
#-- For more detail, man ascii . . .
#-------------------------------------------------------------------------
[ -n "$BASH_VERSION" ] && shopt -s extglob
case "$1" in
oct|[Oo]?([Cc][Tt])|8) Obase=Octal; Numy=3o;;
hex|[Hh]?([Ee][Xx])|16|[Xx]) Obase=Hex; Numy=2X;;
help|?(-)[h?]) sed -n '2,/^[ ]*$/p' $0;exit;;
code|[Cc][Oo][Dd][Ee])sed -n '/case/,$p' $0;exit;;
*) Obase=Decimal
esac # CODE is actually shorter than the chart!
printf "\t\t## $Obase ASCII Chart ##\n\n"; FM1="|%0${Numy:-3d}"; LD=-1
AB="nul soh stx etx eot enq ack bel bs tab nl vt np cr so si dle"
AD="dc1 dc2 dc3 dc4 nak syn etb can em sub esc fs gs rs us sp"
for TOK in $AB $AD; do ABR[$((LD+=1))]=$TOK; done;
ABR[127]=del
IDX=0
while [ $IDX -le 127 ] && CHR="${ABR[$IDX]}"
do ((${#CHR}))&& FM2='%-3s'|| FM2=`printf '\\\\%o ' $IDX`
printf "$FM1 $FM2" "$IDX" $CHR; (( (IDX+=1)%8))||echo '|'
done
exit $?
#!/bin/bash
# ASCII table script, using awk.
# Author: Joseph Steinhauser
# Used in ABS Guide with permission.
#-------------------------------------------------------------------------
#-- File: ascii Print ASCII chart, base 10/8/16 (JETS-2010)
#-------------------------------------------------------------------------
#-- Usage: ascii [oct|dec|hex|help|8|10|16]
#--
#-- This script prints a summary of ASCII char codes from Zero to 127.
#-- Numeric values may be printed in Base10, Octal, or Hex (Base16).
#--
#-- Format Based on: /usr/share/lib/pub/ascii with base-10 as default.
#-- For more detail, man ascii
#-------------------------------------------------------------------------
[ -n "$BASH_VERSION" ] && shopt -s extglob
case "$1" in
oct|[Oo]?([Cc][Tt])|8) Obase=Octal; Numy=3o;;
hex|[Hh]?([Ee][Xx])|16|[Xx]) Obase=Hex; Numy=2X;;
help|?(-)[h?]) sed -n '2,/^[ ]*$/p' $0;exit;;
code|[Cc][Oo][Dd][Ee])sed -n '/case/,$p' $0;exit;;
*) Obase=Decimal
esac
export Obase # CODE is actually shorter than the chart!
awk 'BEGIN{print "\n\t\t## "ENVIRON["Obase"]" ASCII Chart ##\n"
ab="soh,stx,etx,eot,enq,ack,bel,bs,tab,nl,vt,np,cr,so,si,dle,"
ad="dc1,dc2,dc3,dc4,nak,syn,etb,can,em,sub,esc,fs,gs,rs,us,sp"
split(ab ad,abr,",");abr[0]="nul";abr[127]="del";
fm1="|%0'"${Numy:- 4d}"' %-3s"
for(idx=0;idx<128;idx++){fmt=fm1 (++colz%8?"":"|\n")
printf(fmt,idx,(idx in abr)?abr[idx]:sprintf("%c",idx))} }'
exit $?</pre>]
[]
[]
[]
[]
[]
[]
[]
FS=iso # ISO filesystem support in kernel?
grep $FS /proc/filesystems # iso9660
kernel_version=$( awk '{ print $3 }' /proc/version )
CPU=$( awk '/model name/ {print $5}' < /proc/cpuinfo )
if [ "$CPU" = "Pentium(R)" ]
then
run_some_commands
...
else
run_other_commands
...
fi
cpu_speed=$( fgrep "cpu MHz" /proc/cpuinfo | awk '{print $4}' )
# Current operating speed (in MHz) of the cpu on your machine.
# On a laptop this may vary, depending on use of battery
#+ or AC power.
#!/bin/bash
# get-commandline.sh
# Get the command-line parameters of a process.
OPTION=cmdline
# Identify PID.
pid=$( echo $(pidof "$1") | awk '{ print $1 }' )
# Get only first ^^^^^^^^^^^^^^^^^^ of multiple instances.
echo
echo "Process ID of (first instance of) "$1" = $pid"
echo -n "Command-line arguments: "
cat /proc/"$pid"/"$OPTION" | xargs -0 echo
# Formats output: ^^^^^^^^^^^^^^^
# (Thanks, Han Holl, for the fixup!)
echo; echo
# For example:
# sh get-commandline.sh xterm
devfile="/proc/bus/usb/devices"
text="Spd"
USB1="Spd=12"
USB2="Spd=480"
bus_speed=$(fgrep -m 1 "$text" $devfile | awk '{print $9}')
# ^^^^ Stop after first match.
if [ "$bus_speed" = "$USB1" ]
then
echo "USB 1.1 port found."
# Do something appropriate for USB 1.1.
fi
#!/bin/bash
# pid-identifier.sh:
# Gives complete path name to process associated with pid.
ARGNO=1 # Number of arguments the script expects.
E_WRONGARGS=65
E_BADPID=66
E_NOSUCHPROCESS=67
E_NOPERMISSION=68
PROCFILE=exe
if [ $# -ne $ARGNO ]
then
echo "Usage: `basename $0` PID-number" &gt;&2 # Error message &gt;stderr.
exit $E_WRONGARGS
fi
pidno=$( ps ax | grep $1 | awk '{ print $1 }' | grep $1 )
# Checks for pid in "ps" listing, field #1.
# Then makes sure it is the actual process, not the process invoked by this script.
# The last "grep $1" filters out this possibility.
#
# pidno=$( ps ax | awk '{ print $1 }' | grep $1 )
# also works, as Teemu Huovila, points out.
if [ -z "$pidno" ] # If, after all the filtering, the result is a zero-length string,
then #+ no running process corresponds to the pid given.
echo "No such process running."
exit $E_NOSUCHPROCESS
fi
# Alternatively:
# if ! ps $1 &gt; /dev/null 2&gt;&1
# then # no running process corresponds to the pid given.
# echo "No such process running."
# exit $E_NOSUCHPROCESS
# fi
# To simplify the entire process, use "pidof".
if [ ! -r "/proc/$1/$PROCFILE" ] # Check for read permission.
then
echo "Process $1 running, but..."
echo "Can't get read permission on /proc/$1/$PROCFILE."
exit $E_NOPERMISSION # Ordinary user can't access some files in /proc.
fi
# The last two tests may be replaced by:
# if ! kill -0 $1 &gt; /dev/null 2&gt;&1 # '0' is not a signal, but
# this will test whether it is possible
# to send a signal to the process.
# then echo "PID doesn't exist or you're not its owner" &gt;&2
# exit $E_BADPID
# fi
exe_file=$( ls -l /proc/$1 | grep "exe" | awk '{ print $11 }' )
# Or exe_file=$( ls -l /proc/$1/exe | awk '{print $11}' )
#
# /proc/pid-number/exe is a symbolic link
#+ to the complete path name of the invoking process.
if [ -e "$exe_file" ] # If /proc/pid-number/exe exists,
then #+ then the corresponding process exists.
echo "Process #$1 invoked by $exe_file."
else
echo "No such process running."
fi
# This elaborate script can *almost* be replaced by
# ps ax | grep $1 | awk '{ print $5 }'
# However, this will not work...
#+ because the fifth field of 'ps' is argv[0] of the process,
#+ not the executable file path.
#
# However, either of the following would work.
# find /proc/$1/exe -printf '%l\n'
# lsof -aFn -p $1 -d txt | sed -ne 's/^n//p'
# Additional commentary by Stephane Chazelas.
exit 0
#!/bin/bash
# connect-stat.sh
# Note that this script may need modification
#+ to work with a wireless connection.
PROCNAME=pppd # ppp daemon
PROCFILENAME=status # Where to look.
NOTCONNECTED=85
INTERVAL=2 # Update every 2 seconds.
pidno=$( ps ax | grep -v "ps ax" | grep -v grep | grep $PROCNAME |
awk '{ print $1 }' )
# Finding the process number of 'pppd', the 'ppp daemon'.
# Have to filter out the process lines generated by the search itself.
#
# However, as Oleg Philon points out,
#+ this could have been considerably simplified by using "pidof".
# pidno=$( pidof $PROCNAME )
#
# Moral of the story:
#+ When a command sequence gets too complex, look for a shortcut.
if [ -z "$pidno" ] # If no pid, then process is not running.
then
echo "Not connected."
# exit $NOTCONNECTED
else
echo "Connected."; echo
fi
while [ true ] # Endless loop, script can be improved here.
do
if [ ! -e "/proc/$pidno/$PROCFILENAME" ]
# While process running, then "status" file exists.
then
echo "Disconnected."
# exit $NOTCONNECTED
fi
netstat -s | grep "packets received" # Get some connect statistics.
netstat -s | grep "packets delivered"
sleep $INTERVAL
echo; echo
done
exit 0
# As it stands, this script must be terminated with a Control-C.
# Exercises:
# ---------
# Improve the script so it exits on a "q" keystroke.
# Make the script more user-friendly in other ways.
# Fix the script to work with wireless/DSL connections.</pre>]
[]
#!/bin/bash
# String expansion.
# Introduced with version 2 of Bash.
# Strings of the form $'xxx'
#+ have the standard escaped characters interpreted.
echo $'Ringing bell 3 times \a \a \a'
# May only ring once with certain terminals.
# Or ...
# May not ring at all, depending on terminal settings.
echo $'Three form feeds \f \f \f'
echo $'10 newlines \n\n\n\n\n\n\n\n\n\n'
echo $'\102\141\163\150'
# B a s h
# Octal equivalent of characters.
exit
#!/bin/bash
# Indirect variable referencing.
# This has a few of the attributes of references in C++.
a=letter_of_alphabet
letter_of_alphabet=z
echo "a = $a" # Direct reference.
echo "Now a = ${!a}" # Indirect reference.
# The ${!variable} notation is more intuitive than the old
#+ eval var1=\$$var2
echo
t=table_cell_3
table_cell_3=24
echo "t = ${!t}" # t = 24
table_cell_3=387
echo "Value of t changed to ${!t}" # 387
# No 'eval' necessary.
# This is useful for referencing members of an array or table,
#+ or for simulating a multi-dimensional array.
# An indexing option (analogous to pointer arithmetic)
#+ would have been nice. Sigh.
exit 0
# See also, ind-ref.sh example.
#!/bin/bash
# resistor-inventory.sh
# Simple database / table-lookup application.
# ============================================================== #
# Data
B1723_value=470 # Ohms
B1723_powerdissip=.25 # Watts
B1723_colorcode="yellow-violet-brown" # Color bands
B1723_loc=173 # Where they are
B1723_inventory=78 # How many
B1724_value=1000
B1724_powerdissip=.25
B1724_colorcode="brown-black-red"
B1724_loc=24N
B1724_inventory=243
B1725_value=10000
B1725_powerdissip=.125
B1725_colorcode="brown-black-orange"
B1725_loc=24N
B1725_inventory=89
# ============================================================== #
echo
PS3='Enter catalog number: '
echo
select catalog_number in "B1723" "B1724" "B1725"
do
Inv=${catalog_number}_inventory
Val=${catalog_number}_value
Pdissip=${catalog_number}_powerdissip
Loc=${catalog_number}_loc
Ccode=${catalog_number}_colorcode
echo
echo "Catalog number $catalog_number:"
# Now, retrieve value, using indirect referencing.
echo "There are ${!Inv} of [${!Val} ohm / ${!Pdissip} watt]\
resistors in stock." # ^ ^
# As of Bash 4.2, you can replace "ohm" with \u2126 (using echo -e).
echo "These are located in bin # ${!Loc}."
echo "Their color code is \"${!Ccode}\"."
break
done
echo; echo
# Exercises:
# ---------
# 1) Rewrite this script to read its data from an external file.
# 2) Rewrite this script to use arrays,
#+ rather than indirect variable referencing.
# Which method is more straightforward and intuitive?
# Which method is easier to code?
# Notes:
# -----
# Shell scripts are inappropriate for anything except the most simple
#+ database applications, and even then it involves workarounds and kludges.
# Much better is to use a language with native support for data structures,
#+ such as C++ or Java (or even Perl).
exit 0
#!/bin/bash
# cards.sh
# Deals four random hands from a deck of cards.
UNPICKED=0
PICKED=1
DUPE_CARD=99
LOWER_LIMIT=0
UPPER_LIMIT=51
CARDS_IN_SUIT=13
CARDS=52
declare -a Deck
declare -a Suits
declare -a Cards
# It would have been easier to implement and more intuitive
#+ with a single, 3-dimensional array.
# Perhaps a future version of Bash will support multidimensional arrays.
initialize_Deck ()
{
i=$LOWER_LIMIT
until [ "$i" -gt $UPPER_LIMIT ]
do
Deck[i]=$UNPICKED # Set each card of "Deck" as unpicked.
let "i += 1"
done
echo
}
initialize_Suits ()
{
Suits[0]=C #Clubs
Suits[1]=D #Diamonds
Suits[2]=H #Hearts
Suits[3]=S #Spades
}
initialize_Cards ()
{
Cards=(2 3 4 5 6 7 8 9 10 J Q K A)
# Alternate method of initializing an array.
}
pick_a_card ()
{
card_number=$RANDOM
let "card_number %= $CARDS" # Restrict range to 0 - 51, i.e., 52 cards.
if [ "${Deck[card_number]}" -eq $UNPICKED ]
then
Deck[card_number]=$PICKED
return $card_number
else
return $DUPE_CARD
fi
}
parse_card ()
{
number=$1
let "suit_number = number / CARDS_IN_SUIT"
suit=${Suits[suit_number]}
echo -n "$suit-"
let "card_no = number % CARDS_IN_SUIT"
Card=${Cards[card_no]}
printf %-4s $Card
# Print cards in neat columns.
}
seed_random () # Seed random number generator.
{ # What happens if you don't do this?
seed=`eval date +%s`
let "seed %= 32766"
RANDOM=$seed
} # Consider other methods of seeding the random number generator.
deal_cards ()
{
echo
cards_picked=0
while [ "$cards_picked" -le $UPPER_LIMIT ]
do
pick_a_card
t=$?
if [ "$t" -ne $DUPE_CARD ]
then
parse_card $t
u=$cards_picked+1
# Change back to 1-based indexing, temporarily. Why?
let "u %= $CARDS_IN_SUIT"
if [ "$u" -eq 0 ] # Nested if/then condition test.
then
echo
echo
fi # Each hand set apart with a blank line.
let "cards_picked += 1"
fi
done
echo
return 0
}
# Structured programming:
# Entire program logic modularized in functions.
#===============
seed_random
initialize_Deck
initialize_Suits
initialize_Cards
deal_cards
#===============
exit
# Exercise 1:
# Add comments to thoroughly document this script.
# Exercise 2:
# Add a routine (function) to print out each hand sorted in suits.
# You may add other bells and whistles if you like.
# Exercise 3:
# Simplify and streamline the logic of the script.</pre>]
#!/bin/bash
# This simple script removes blank lines from a file.
# No argument checking.
#
# You might wish to add something like:
#
# E_NOARGS=85
# if [ -z "$1" ]
# then
# echo "Usage: `basename $0` target-file"
# exit $E_NOARGS
# fi
sed -e /^$/d "$1"
# Same as
# sed -e '/^$/d' filename
# invoked from the command-line.
# The '-e' means an "editing" command follows (optional here).
# '^' indicates the beginning of line, '$' the end.
# This matches lines with nothing between the beginning and the end --
#+ blank lines.
# The 'd' is the delete command.
# Quoting the command-line arg permits
#+ whitespace and special characters in the filename.
# Note that this script doesn't actually change the target file.
# If you need to do that, redirect its output.
exit
#!/bin/bash
# subst.sh: a script that substitutes one pattern for
#+ another in a file,
#+ i.e., "sh subst.sh Smith Jones letter.txt".
# Jones replaces Smith.
ARGS=3 # Script requires 3 arguments.
E_BADARGS=85 # Wrong number of arguments passed to script.
if [ $# -ne "$ARGS" ]
then
echo "Usage: `basename $0` old-pattern new-pattern filename"
exit $E_BADARGS
fi
old_pattern=$1
new_pattern=$2
if [ -f "$3" ]
then
file_name=$3
else
echo "File \"$3\" does not exist."
exit $E_BADARGS
fi
# -----------------------------------------------
# Here is where the heavy work gets done.
sed -e "s/$old_pattern/$new_pattern/g" $file_name
# -----------------------------------------------
# 's' is, of course, the substitute command in sed,
#+ and /pattern/ invokes address matching.
# The 'g,' or global flag causes substitution for EVERY
#+ occurence of $old_pattern on each line, not just the first.
# Read the 'sed' docs for an in-depth explanation.
exit $? # Redirect the output of this script to write to a file.
#!/bin/bash
# logging-wrapper.sh
# Generic shell wrapper that performs an operation
#+ and logs it.
DEFAULT_LOGFILE=logfile.txt
# Set the following two variables.
OPERATION=
# Can be a complex chain of commands,
#+ for example an awk script or a pipe . . .
LOGFILE=
if [ -z "$LOGFILE" ]
then # If not set, default to ...
LOGFILE="$DEFAULT_LOGFILE"
fi
# Command-line arguments, if any, for the operation.
OPTIONS="$@"
# Log it.
echo "`date` + `whoami` + $OPERATION "$@"" &gt;&gt; $LOGFILE
# Now, do it.
exec $OPERATION "$@"
# It's necessary to do the logging before the operation.
# Why?
#!/bin/bash
# pr-ascii.sh: Prints a table of ASCII characters.
START=33 # Range of printable ASCII characters (decimal).
END=127 # Will not work for unprintable characters (&gt; 127).
echo " Decimal Hex Character" # Header.
echo " ------- --- ---------"
for ((i=START; i<=END; i++))
do
echo $i | awk '{printf(" %3d %2x %c\n", $1, $1, $1)}'
# The Bash printf builtin will not work in this context:
# printf "%c" "$i"
done
exit 0
# Decimal Hex Character
# ------- --- ---------
# 33 21 !
# 34 22 "
# 35 23 #
# 36 24 $
#
# . . .
#
# 122 7a z
# 123 7b {
# 124 7c |
# 125 7d }
# Redirect the output of this script to a file
#+ or pipe it to "more": sh pr-asc.sh | more
#!/bin/bash
# Adds up a specified column (of numbers) in the target file.
# Floating-point (decimal) numbers okay, because awk can handle them.
ARGS=2
E_WRONGARGS=85
if [ $# -ne "$ARGS" ] # Check for proper number of command-line args.
then
echo "Usage: `basename $0` filename column-number"
exit $E_WRONGARGS
fi
filename=$1
column_number=$2
# Passing shell variables to the awk part of the script is a bit tricky.
# One method is to strong-quote the Bash-script variable
#+ within the awk script.
# $'$BASH_SCRIPT_VAR'
# ^ ^
# This is done in the embedded awk script below.
# See the awk documentation for more details.
# A multi-line awk script is here invoked by
# awk '
# ...
# ...
# ...
# '
# Begin awk script.
# -----------------------------
awk '
{ total += $'"${column_number}"'
}
END {
print total
}
' "$filename"
# -----------------------------
# End awk script.
# It may not be safe to pass shell variables to an embedded awk script,
#+ so Stephane Chazelas proposes the following alternative:
# ---------------------------------------
# awk -v column_number="$column_number" '
# { total += $column_number
# }
# END {
# print total
# }' "$filename"
# ---------------------------------------
exit 0
#!/bin/bash
# Shell commands may precede the Perl script.
echo "This precedes the embedded Perl script within \"$0\"."
echo "==============================================================="
perl -e 'print "This line prints from an embedded Perl script.\n";'
# Like sed, Perl also uses the "-e" option.
echo "==============================================================="
echo "However, the script may also contain shell and system commands."
exit 0
#!/bin/bash
# bashandperl.sh
echo "Greetings from the Bash part of the script, $0."
# More Bash commands may follow here.
exit
# End of Bash part of the script.
# =======================================================
#!/usr/bin/perl
# This part of the script must be invoked with
# perl -x bashandperl.sh
print "Greetings from the Perl part of the script, $0.\n";
# Perl doesn't seem to like "echo" ...
# More Perl commands may follow here.
# End of Perl part of the script.
#!/bin/bash
# ex56py.sh
# Shell commands may precede the Python script.
echo "This precedes the embedded Python script within \"$0.\""
echo "==============================================================="
python -c 'print "This line prints from an embedded Python script.\n";'
# Unlike sed and perl, Python uses the "-c" option.
python -c 'k = raw_input( "Hit a key to exit to outer script. " )'
echo "==============================================================="
echo "However, the script may also contain shell and system commands."
exit 0
#!/bin/bash
# Courtesy of:
# http://elinux.org/RPi_Text_to_Speech_(Speech_Synthesis)
# You must be on-line for this script to work,
#+ so you can access the Google translation server.
# Of course, mplayer must be present on your computer.
speak()
{
local IFS=+
# Invoke mplayer, then connect to Google translation server.
/usr/bin/mplayer -ao alsa -really-quiet -noconsolecontrols \
"http://translate.google.com/translate_tts?tl=en&q="$*""
# Google translates, but can also speak.
}
LINES=4
spk=$(tail -$LINES $0) # Tail end of same script!
speak "$spk"
exit
# Browns. Nice talking to you.</pre>]
[]
device0="/dev/sda2" # / (root directory)
if [ -b "$device0" ]
then
echo "$device0 is a block device."
fi
# /dev/sda2 is a block device.
device1="/dev/ttyS1" # PCMCIA modem card.
if [ -c "$device1" ]
then
echo "$device1 is a character device."
fi
# /dev/ttyS1 is a character device.
function show_input_type()
{
[ -p /dev/fd/0 ] && echo PIPE || echo STDIN
}
show_input_type "Input" # STDIN
echo "Input" | show_input_type # PIPE
# This example courtesy of Carl Anderson.
#!/bin/bash
# broken-link.sh
# Written by Lee bigelow <ligelowbee@yahoo.com&gt;
# Used in ABS Guide with permission.
# A pure shell script to find dead symlinks and output them quoted
#+ so they can be fed to xargs and dealt with :)
#+ eg. sh broken-link.sh /somedir /someotherdir|xargs rm
#
# This, however, is a better method:
#
# find "somedir" -type l -print0|\
# xargs -r0 file|\
# grep "broken symbolic"|
# sed -e 's/^\|: *broken symbolic.*$/"/g'
#
#+ but that wouldn't be pure Bash, now would it.
# Caution: beware the /proc file system and any circular links!
################################################################
# If no args are passed to the script set directories-to-search
#+ to current directory. Otherwise set the directories-to-search
#+ to the args passed.
######################
[ $# -eq 0 ] && directorys=`pwd` || directorys=$@
# Setup the function linkchk to check the directory it is passed
#+ for files that are links and don't exist, then print them quoted.
# If one of the elements in the directory is a subdirectory then
#+ send that subdirectory to the linkcheck function.
##########
linkchk () {
for element in $1/*; do
[ -h "$element" -a ! -e "$element" ] && echo \"$element\"
[ -d "$element" ] && linkchk $element
# Of course, '-h' tests for symbolic link, '-d' for directory.
done
}
# Send each arg that was passed to the script to the linkchk() function
#+ if it is a valid directoy. If not, then print the error message
#+ and usage info.
##################
for directory in $directorys; do
if [ -d $directory ]
then linkchk $directory
else
echo "$directory is not a directory"
echo "Usage: $0 dir1 dir2 ..."
fi
done
exit $?
Deprecate
...
To pray against, as an evil;
to seek to avert by prayer;
to desire the removal of;
to seek deliverance from;
to express deep regret for;
to disapprove of strongly.</pre>]
a=3
if [ "$a" -gt 0 ]
then
if [ "$a" -lt 5 ]
then
echo "The value of \"a\" lies somewhere between 0 and 5."
fi
fi
# Same result as:
if [ "$a" -gt 0 ] && [ "$a" -lt 5 ]
then
echo "The value of \"a\" lies somewhere between 0 and 5."
fi</pre>]
# This line is a comment.
echo "A comment will follow." # Comment here.
# ^ Note whitespace before #
# A tab precedes this comment.
initial=( `cat "$startfile" | sed -e '/#/d' | tr -d '\n' |\
# Delete lines containing '#' comment character.
sed -e 's/\./\. /g' -e 's/_/_ /g'` )
# Excerpted from life.sh script
echo "The # here does not begin a comment."
echo 'The # here does not begin a comment.'
echo The \# here does not begin a comment.
echo The # here begins a comment.
echo ${PATH#*:} # Parameter substitution, not a comment.
echo $(( 2#101011 )) # Base conversion, not a comment.
# Thanks, S.C.
echo hello; echo there
if [ -x "$filename" ]; then # Note the space after the semicolon.
#+ ^^
echo "File $filename exists."; cp $filename $filename.bak
else # ^^
echo "File $filename not found."; touch $filename
fi; echo "File test complete."
case "$variable" in
abc) echo "\$variable = abc" ;;
xyz) echo "\$variable = xyz" ;;
esac
let "t2 = ((a = 9, 15 / 3))"
# Set "a = 9" and "t2 = 15 / 3"
for file in /{,usr/}bin/*calc
# ^ Find all executable files ending in "calc"
#+ in /bin and /usr/bin directories.
do
if [ -x "$file" ]
then
echo $file
fi
done
# /bin/ipcalc
# /usr/bin/kcalc
# /usr/bin/oidcalc
# /usr/bin/oocalc
# Thank you, Rory Winston, for pointing this out.
:
echo $? # 0
while :
do
operation-1
operation-2
...
operation-n
done
# Same as:
# while true
# do
# ...
# done
if condition
then : # Do nothing and branch ahead
else # Or else ...
take-some-action
fi
: ${username=`whoami`}
# ${username=`whoami`} Gives an error without the leading :
# unless "username" is a command or builtin...
: ${1?"Usage: $0 ARGUMENT"} # From "usage-message.sh example script.
: ${HOSTNAME?} ${USER?} ${MAIL?}
# Prints error message
#+ if one or more of essential environmental variables not set.
: &gt; data.xxx # File "data.xxx" now empty.
# Same effect as cat /dev/null &gt;data.xxx
# However, this does not fork a new process, since ":" is a builtin.
: This is a comment that generates an error, ( if [ $x -eq 3] ).
:()
{
echo "The name of this function is "$FUNCNAME" "
# Why use a colon as a function name?
# It's a way of obfuscating your code.
}
:
# The name of this function is :
not_empty ()
{
:
} # Contains a : (null command), and so is not empty.
(( var0 = var1<98?9:21 ))
# ^ ^
# if [ "$var1" -lt 98 ]
# then
# var0=9
# else
# var0=21
# fi
var1=5
var2=23skidoo
echo $var1 # 5
echo $var2 # 23skidoo
(a=hello; echo $a)
a=123
( a=321; )
echo "a = $a" # a = 123
# "a" within parentheses acts like a local variable.
Array=(element1 element2 element3)
echo \"{These,words,are,quoted}\" # " prefix and suffix
# "These" "words" "are" "quoted"
cat {file1,file2,file3} &gt; combined_file
# Concatenates the files file1, file2, and file3 into combined_file.
cp file22.{txt,backup}
# Copies "file22.txt" to "file22.backup"
echo {a..z} # a b c d e f g h i j k l m n o p q r s t u v w x y z
# Echoes characters between a and z.
echo {0..3} # 0 1 2 3
# Echoes characters between 0 and 3.
base64_charset=( {A..Z} {a..z} {0..9} + / = )
# Initializing an array, using extended brace expansion.
# From vladz's "base64.sh" example script.
a=123
{ a=321; }
echo "a = $a" # a = 321 (value inside code block)
# Thanks, S.C.
#!/bin/bash
# Reading lines in /etc/fstab.
File=/etc/fstab
{
read line1
read line2
} < $File
echo "First line in $File is:"
echo "$line1"
echo
echo "Second line in $File is:"
echo "$line2"
exit 0
# Now, how do you parse the separate fields of each line?
# Hint: use awk, or . . .
# . . . Hans-Joerg Diers suggests using the "set" Bash builtin.
#!/bin/bash
# rpm-check.sh
# Queries an rpm file for description, listing,
#+ and whether it can be installed.
# Saves output to a file.
#
# This script illustrates using a code block.
SUCCESS=0
E_NOARGS=65
if [ -z "$1" ]
then
echo "Usage: `basename $0` rpm-file"
exit $E_NOARGS
fi
{ # Begin code block.
echo
echo "Archive Description:"
rpm -qpi $1 # Query description.
echo
echo "Archive Listing:"
rpm -qpl $1 # Query listing.
echo
rpm -i --test $1 # Query whether rpm file can be installed.
if [ "$?" -eq $SUCCESS ]
then
echo "$1 can be installed."
else
echo "$1 cannot be installed."
fi
echo # End code block.
} &gt; "$1.test" # Redirects output of everything in block to file.
echo "Results of rpm test in file $1.test"
# See rpm man page for explanation of options.
exit 0
ls . | xargs -i -t cp ./{} $1
# ^^ ^^
# From "ex42.sh" (copydir.sh) example.
Array[1]=slot_1
echo ${Array[1]}
a=3
b=7
echo $[$a+$b] # 10
echo $[$a*$b] # 21
command_test () { type "$1" &&gt;/dev/null; }
# ^
cmd=rmdir # Legitimate command.
command_test $cmd; echo $? # 0
cmd=bogus_command # Illegitimate command
command_test $cmd; echo $? # 1
veg1=carrots
veg2=tomatoes
if [[ "$veg1" < "$veg2" ]]
then
echo "Although $veg1 precede $veg2 in the dictionary,"
echo -n "this does not necessarily imply anything "
echo "about my culinary preferences."
else
echo "What kind of dictionary are you using, anyhow?"
fi
echo ls -l | sh
# Passes the output of "echo ls -l" to the shell,
#+ with the same result as a simple "ls -l".
cat *.lst | sort | uniq
# Merges and sorts all ".lst" files, then deletes duplicate lines.
#!/bin/bash
# uppercase.sh : Changes input to uppercase.
tr 'a-z' 'A-Z'
# Letter ranges must be quoted
#+ to prevent filename generation from single-letter filenames.
exit 0
cat file1 file2 | ls -l | sort
# The output from "cat file1 file2" disappears.
variable="initial_value"
echo "new_value" | read variable
echo "variable = $variable" # variable = initial_value
#!/bin/bash
# background-loop.sh
for i in 1 2 3 4 5 6 7 8 9 10 # First loop.
do
echo -n "$i "
done & # Run this loop in background.
# Will sometimes execute after second loop.
echo # This 'echo' sometimes will not display.
for i in 11 12 13 14 15 16 17 18 19 20 # Second loop.
do
echo -n "$i "
done
echo # This 'echo' sometimes will not display.
# ======================================================
# The expected output from the script:
# 1 2 3 4 5 6 7 8 9 10
# 11 12 13 14 15 16 17 18 19 20
# Sometimes, though, you get:
# 11 12 13 14 15 16 17 18 19 20
# 1 2 3 4 5 6 7 8 9 10 bozo $
# (The second 'echo' doesn't execute. Why?)
# Occasionally also:
# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
# (The first 'echo' doesn't execute. Why?)
# Very rarely something like:
# 11 12 13 1 2 3 4 5 6 7 8 9 10 14 15 16 17 18 19 20
# The foreground loop preempts the background one.
exit 0
# Nasimuddin Ansari suggests adding sleep 1
#+ after the echo -n "$i" in lines 6 and 14,
#+ for some real fun.
if [ $file1 -ot $file2 ]
then # ^
echo "File $file1 is older than $file2."
fi
if [ "$a" -eq "$b" ]
then # ^
echo "$a is equal to $b."
fi
if [ "$c" -eq 24 -a "$d" -eq 47 ]
then # ^ ^
echo "$c equals 24 and $d equals 47."
fi
param2=${param1:-$DEFAULTVAL}
# ^
(cd /source/directory && tar cf - . ) | (cd /dest/directory && tar xpvf -)
# Move entire file tree from one directory to another
# [courtesy Alan Cox <a.cox@swansea.ac.uk&gt;, with a minor change]
# 1) cd /source/directory
# Source directory, where the files to be moved are.
# 2) &&
# "And-list": if the 'cd' operation successful,
# then execute the next command.
# 3) tar cf - .
# The 'c' option 'tar' archiving command creates a new archive,
# the 'f' (file) option, followed by '-' designates the target file
# as stdout, and do it in current directory tree ('.').
# 4) |
# Piped to ...
# 5) ( ... )
# a subshell
# 6) cd /dest/directory
# Change to the destination directory.
# 7) &&
# "And-list", as above
# 8) tar xpvf -
# Unarchive ('x'), preserve ownership and file permissions ('p'),
# and send verbose messages to stdout ('v'),
# reading data from stdin ('f' followed by '-').
#
# Note that 'x' is a command, and 'p', 'v', 'f' are options.
#
# Whew!
# More elegant than, but equivalent to:
# cd source/directory
# tar cf - . | (cd ../dest/directory; tar xpvf -)
#
# Also having same effect:
# cp -a /source/directory/* /dest/directory
# Or:
# cp -a /source/directory/* /source/directory/.[^.]* /dest/directory
# If there are hidden files in /source/directory.
bunzip2 -c linux-2.6.16.tar.bz2 | tar xvf -
# --uncompress tar file-- | --then pass it to "tar"--
# If "tar" has not been patched to handle "bunzip2",
#+ this needs to be done in two discrete steps, using a pipe.
# The purpose of the exercise is to unarchive "bzipped" kernel source.
#!/bin/bash
# Backs up all files in current directory modified within last 24 hours
#+ in a "tarball" (tarred and gzipped file).
BACKUPFILE=backup-$(date +%m-%d-%Y)
# Embeds date in backup filename.
# Thanks, Joshua Tschida, for the idea.
archive=${1:-$BACKUPFILE}
# If no backup-archive filename specified on command-line,
#+ it will default to "backup-MM-DD-YYYY.tar.gz."
tar cvf - `find . -mtime -1 -type f -print` &gt; $archive.tar
gzip $archive.tar
echo "Directory $PWD backed up in archive file \"$archive.tar.gz\"."
# Stephane Chazelas points out that the above code will fail
#+ if there are too many files found
#+ or if any filenames contain blank characters.
# He suggests the following alternatives:
# -------------------------------------------------------------------
# find . -mtime -1 -type f -print0 | xargs -0 tar rvf "$archive.tar"
# using the GNU version of "find".
# find . -mtime -1 -type f -exec tar rvf "$archive.tar" '{}' \;
# portable to other UNIX flavors, but much slower.
# -------------------------------------------------------------------
exit 0
var="-n"
echo $var
# Has the effect of "echo -n", and outputs nothing.
a=28
echo $a # 28
let "z = 5 % 3"
echo $z # 2
#!/bin/bash
# Embedding Ctl-H in a string.
a="^H^H" # Two Ctl-H's -- backspaces
# ctl-V ctl-H, using vi/vim
echo "abcdef" # abcdef
echo
echo -n "abcdef$a " # abcd f
# Space at end ^ ^ Backspaces twice.
echo
echo -n "abcdef$a" # abcdef
# No space at end ^ Doesn't backspace (why?).
# Results may not be quite as expected.
echo; echo
# Constantin Hagemeier suggests trying:
# a=$'\010\010'
# a=$'\b\b'
# a=$'\x08\x08'
# But, this does not change the results.
########################################
# Now, try this.
rubout="^H^H^H^H^H" # 5 x Ctl-H.
echo -n "12345678"
sleep 2
echo -n "$rubout"
sleep 2
#!/bin/bash
# Thank you, Lee Maschmeyer, for this example.
read -n 1 -s -p \
$'Control-M leaves cursor at beginning of this line. Press Enter. \x0d'
# Of course, '0d' is the hex equivalent of Control-M.
echo &gt;&2 # The '-s' makes anything typed silent,
#+ so it is necessary to go to new line explicitly.
read -n 1 -s -p $'Control-J leaves cursor on next line. \x0a'
# '0a' is the hex equivalent of Control-J, linefeed.
echo &gt;&2
###
read -n 1 -s -p $'And Control-K\x0bgoes straight down.'
echo &gt;&2 # Control-K is vertical tab.
# A better example of the effect of a vertical tab is:
var=$'\x0aThis is the bottom line\x0bThis is the top line\x0a'
echo "$var"
# This works the same way as the above example. However:
echo "$var" | col
# This causes the right end of the line to be higher than the left end.
# It also explains why we started and ended with a line feed --
#+ to avoid a garbled screen.
# As Lee Maschmeyer explains:
# --------------------------
# In the [first vertical tab example] . . . the vertical tab
#+ makes the printing go straight down without a carriage return.
# This is true only on devices, such as the Linux console,
#+ that can't go "backward."
# The real purpose of VT is to go straight UP, not down.
# It can be used to print superscripts on a printer.
# The col utility can be used to emulate the proper behavior of VT.
exit 0
echo -e '\x0a'
echo <Ctl-V&gt;<Ctl-J&gt;
ls | { read firstline; read secondline; }
# Error. The code block in braces runs as a subshell,
#+ so the output of "ls" cannot be passed to variables within the block.
echo "First line is $firstline; second line is $secondline" # Won't work.
# Thanks, S.C.</pre>]
diff <(ls $first_directory) <(ls $second_directory)
read -a list < <( od -Ad -w24 -t u2 /dev/urandom )
# Read a list of random numbers from /dev/urandom,
#+ process with "od"
#+ and feed into stdin of "read" . . .
# From "insertion-sort.bash" example script.
# Courtesy of JuanJo Ciarlante.
PORT=6881 # bittorrent
# Scan the port to make sure nothing nefarious is going on.
netcat -l $PORT | tee&gt;(md5sum -&gt;mydata-orig.md5) |
gzip | tee&gt;(md5sum - | sed 's/-$/mydata.lz2/'&gt;mydata-gz.md5)&gt;mydata.gz
# Check the decompression:
gzip -d<mydata.gz | md5sum -c mydata-orig.md5)
# The MD5sum of the original checks stdin and detects compression issues.
# Bill Davidsen contributed this example
#+ (with light edits by the ABS Guide author).
cat <(ls -l)
# Same as ls -l | cat
sort -k 9 <(ls -l /bin) <(ls -l /usr/bin) <(ls -l /usr/X11R6/bin)
# Lists all the files in the 3 main 'bin' directories, and sorts by filename.
# Note that three (count 'em) distinct commands are fed to 'sort'.
diff <(command1) <(command2) # Gives difference in command output.
tar cf &gt;(bzip2 -c &gt; file.tar.bz2) $directory_name
# Calls "tar cf /dev/fd/?? $directory_name", and "bzip2 -c &gt; file.tar.bz2".
#
# Because of the /dev/fd/<n&gt; system feature,
# the pipe between both commands does not need to be named.
#
# This can be emulated.
#
bzip2 -c < pipe &gt; file.tar.bz2&
tar cf pipe $directory_name
rm pipe
# or
exec 3&gt;&1
tar cf /dev/fd/4 $directory_name 4&gt;&1 &gt;&3 3&gt;&- | bzip2 -c &gt; file.tar.bz2 3&gt;&-
exec 3&gt;&-
# Thanks, Stéphane Chazelas
#!/bin/bash
# wr-ps.bash: while-read loop with process substitution.
# This example contributed by Tomas Pospisek.
# (Heavily edited by the ABS Guide author.)
echo
echo "random input" | while read i
do
global=3D": Not available outside the loop."
# ... because it runs in a subshell.
done
echo "\$global (from outside the subprocess) = $global"
# $global (from outside the subprocess) =
echo; echo "--"; echo
while read i
do
echo $i
global=3D": Available outside the loop."
# ... because it does NOT run in a subshell.
done < <( echo "random input" )
# ^ ^
echo "\$global (using process substitution) = $global"
# Random input
# $global (using process substitution) = 3D: Available outside the loop.
echo; echo "##########"; echo
# And likewise . . .
declare -a inloop
index=0
cat $0 | while read line
do
inloop[$index]="$line"
((index++))
# It runs in a subshell, so ...
done
echo "OUTPUT = "
echo ${inloop[*]} # ... nothing echoes.
echo; echo "--"; echo
declare -a outloop
index=0
while read line
do
outloop[$index]="$line"
((index++))
# It does NOT run in a subshell, so ...
done < <( cat $0 )
echo "OUTPUT = "
echo ${outloop[*]} # ... the entire script echoes.
exit $?
#!/bin/bash
# psub.bash
# As inspired by Diego Molina (thanks!).
declare -a array0
while read
do
array0[${#array0[@]}]="$REPLY"
done < <( sed -e 's/bash/CRASH-BANG!/' $0 | grep bin | awk '{print $1}' )
# Sets the default 'read' variable, $REPLY, by process substitution,
#+ then copies it into an array.
echo "${array0[@]}"
exit $?
# ====================================== #
bash psub.bash
#!/bin/CRASH-BANG! done #!/bin/CRASH-BANG!
# Script fragment taken from SuSE distribution:
# --------------------------------------------------------------#
while read des what mask iface; do
# Some commands ...
done < <(route -n)
# ^ ^ First < is redirection, second is process substitution.
# To test it, let's make it do something.
while read des what mask iface; do
echo $des $what $mask $iface
done < <(route -n)
# Output:
# Kernel IP routing table
# Destination Gateway Genmask Flags Metric Ref Use Iface
# 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
# --------------------------------------------------------------#
# As Stéphane Chazelas points out,
#+ an easier-to-understand equivalent is:
route -n |
while read des what mask iface; do # Variables set from output of pipe.
echo $des $what $mask $iface
done # This yields the same output as above.
# However, as Ulrich Gayer points out . . .
#+ this simplified equivalent uses a subshell for the while loop,
#+ and therefore the variables disappear when the pipe terminates.
# --------------------------------------------------------------#
# However, Filip Moritz comments that there is a subtle difference
#+ between the above two examples, as the following shows.
(
route -n | while read x; do ((y++)); done
echo $y # $y is still unset
while read x; do ((y++)); done < <(route -n)
echo $y # $y has the number of lines of output of route -n
)
More generally spoken
(
: | x=x
# seems to start a subshell like
: | ( x=x )
# while
x=x < <(:)
# does not
)
# This is useful, when parsing csv and the like.
# That is, in effect, what the original SuSE code fragment does.</pre>]
case=value0 # Causes problems.
23skidoo=value1 # Also problems.
# Variable names starting with a digit are reserved by the shell.
# Try _23skidoo=value1. Starting variables with an underscore is okay.
# However . . . using just an underscore will not work.
_=25
echo $_ # $_ is a special variable set to last arg of last command.
# But . . . _ is a valid function name!
xyz((!*=value2 # Causes severe problems.
# As of version 3 of Bash, periods are not allowed within variable names.
var-1=23
# Use 'var_1' instead.
function-whatever () # Error
# Use 'function_whatever ()' instead.
# As of version 3 of Bash, periods are not allowed within function names.
function.whatever () # Error
# Use 'functionWhatever ()' instead.
do_something ()
{
echo "This function does something with \"$1\"."
}
do_something=do_something
do_something do_something
# All this is legal, but highly confusing.
var1 = 23 # 'var1=23' is correct.
# On line above, Bash attempts to execute command "var1"
# with the arguments "=" and "23".
let c = $a - $b # Instead: let c=$a-$b or let "c = $a - $b"
if [ $a -le 5] # if [ $a -le 5 ] is correct.
# ^^ if [ "$a" -le 5 ] is even better.
# [[ $a -le 5 ]] also works.
{ ls -l; df; echo "Done." }
# bash: syntax error: unexpected end of file
{ ls -l; df; echo "Done."; }
# ^ ### Final command needs semicolon.
#!/bin/bash
echo "uninitialized_var = $uninitialized_var"
# uninitialized_var =
# However . . .
# if $BASH_VERSION ≥ 4.2; then
if [[ ! -v uninitialized_var ]]
then
uninitialized_var=0 # Initialize it to zero!
fi
if [ "$a" = 273 ] # Is $a an integer or string?
if [ "$a" -eq 273 ] # If $a is an integer.
# Sometimes you can interchange -eq and = without adverse consequences.
# However . . .
a=273.0 # Not an integer.
if [ "$a" = 273 ]
then
echo "Comparison works."
else
echo "Comparison does not work."
fi # Comparison does not work.
# Same with a=" 273" and a="0273".
# Likewise, problems trying to use "-eq" with non-integer values.
if [ "$a" -eq 273.0 ]
then
echo "a = $a"
fi # Aborts with an error message.
# test.sh: [: 273.0: integer expression expected
#!/bin/bash
# bad-op.sh: Trying to use a string comparison on integers.
echo
number=1
# The following while-loop has two errors:
#+ one blatant, and the other subtle.
while [ "$number" < 5 ] # Wrong! Should be: while [ "$number" -lt 5 ]
do
echo -n "$number "
let "number += 1"
done
# Attempt to run this bombs with the error message:
#+ bad-op.sh: line 10: 5: No such file or directory
# Within single brackets, "<" must be escaped,
#+ and even then, it's still wrong for comparing integers.
echo "---------------------"
while [ "$number" \< 5 ] # 1 2 3 4
do #
echo -n "$number " # It *seems* to work, but . . .
let "number += 1" #+ it actually does an ASCII comparison,
done #+ rather than a numerical one.
echo; echo "---------------------"
# This can cause problems. For example:
lesser=5
greater=105
if [ "$greater" \< "$lesser" ]
then
echo "$greater is less than $lesser"
fi # 105 is less than 5
# In fact, "105" actually is less than "5"
#+ in a string comparison (ASCII sort order).
echo
exit 0
let "a = hello, you"
echo "$a" # 0
command1 2&gt; - | command2
# Trying to redirect error output of command1 into a pipe . . .
# . . . will not work.
command1 2&gt;& - | command2 # Also futile.
Thanks, S.C.
#!/bin/bash
minimum_version=2
# Since Chet Ramey is constantly adding features to Bash,
# you may set $minimum_version to 2.XX, 3.XX, or whatever is appropriate.
E_BAD_VERSION=80
if [ "$BASH_VERSION" \< "$minimum_version" ]
then
echo "This script works only with Bash, version $minimum or greater."
echo "Upgrade strongly recommended."
exit $E_BAD_VERSION
fi
...
var=1 && ((--var)) && echo $var
# ^^^^^^^^^ Here the and-list terminates with exit status 1.
# $var doesn't echo!
echo $? # 1
#!/bin/bash
echo "Here"
unix2dos $0 # Script changes itself to DOS format.
chmod 755 $0 # Change back to execute permission.
# The 'unix2dos' command removes execute permission.
./$0 # Script tries to run itself again.
# But it won't work as a DOS file.
echo "There"
exit 0
add2 ()
{
echo "Whatever ... " # Delete this line!
let "retval = $1 + $2"
echo $retval
}
num1=12
num2=43
echo "Sum of $num1 and $num2 = $(add2 $num1 $num2)"
# Sum of 12 and 43 = Whatever ...
# 55
# The "echoes" concatenate.
WHATEVER=/home/bozo
export WHATEVER
exit 0
#!/bin/bash
# Pitfalls of variables in a subshell.
outer_variable=outer
echo
echo "outer_variable = $outer_variable"
echo
(
# Begin subshell
echo "outer_variable inside subshell = $outer_variable"
inner_variable=inner # Set
echo "inner_variable inside subshell = $inner_variable"
outer_variable=inner # Will value change globally?
echo "outer_variable inside subshell = $outer_variable"
# Will 'exporting' make a difference?
# export inner_variable
# export outer_variable
# Try it and see.
# End subshell
)
echo
echo "inner_variable outside subshell = $inner_variable" # Unset.
echo "outer_variable outside subshell = $outer_variable" # Unchanged.
echo
exit 0
# What happens if you uncomment lines 19 and 20?
# Does it make a difference?
#!/bin/bash
# badread.sh:
# Attempting to use 'echo and 'read'
#+ to assign variables non-interactively.
# shopt -s lastpipe
a=aaa
b=bbb
c=ccc
echo "one two three" | read a b c
# Try to reassign a, b, and c.
echo
echo "a = $a" # a = aaa
echo "b = $b" # b = bbb
echo "c = $c" # c = ccc
# Reassignment failed.
### However . . .
## Uncommenting line 6:
# shopt -s lastpipe
##+ fixes the problem!
### This is a new feature in Bash, version 4.2.
# ------------------------------
# Try the following alternative.
var=`echo "one two three"`
set -- $var
a=$1; b=$2; c=$3
echo "-------"
echo "a = $a" # a = one
echo "b = $b" # b = two
echo "c = $c" # c = three
# Reassignment succeeded.
# ------------------------------
# Note also that an echo to a 'read' works within a subshell.
# However, the value of the variable changes *only* within the subshell.
a=aaa # Starting all over again.
b=bbb
c=ccc
echo; echo
echo "one two three" | ( read a b c;
echo "Inside subshell: "; echo "a = $a"; echo "b = $b"; echo "c = $c" )
# a = one
# b = two
# c = three
echo "-----------------"
echo "Outside subshell: "
echo "a = $a" # a = aaa
echo "b = $b" # b = bbb
echo "c = $c" # c = ccc
echo
exit 0
# Loop piping troubles.
# This example by Anthony Richardson,
#+ with addendum by Wilbert Berendsen.
foundone=false
find $HOME -type f -atime +30 -size 100k |
while true
do
read f
echo "$f is over 100KB and has not been accessed in over 30 days"
echo "Consider moving the file to archives."
foundone=true
# ------------------------------------
echo "Subshell level = $BASH_SUBSHELL"
# Subshell level = 1
# Yes, we're inside a subshell.
# ------------------------------------
done
# foundone will always be false here since it is
#+ set to true inside a subshell
if [ $foundone = false ]
then
echo "No files need archiving."
fi
# =====================Now, here is the correct way:=================
foundone=false
for f in $(find $HOME -type f -atime +30 -size 100k) # No pipe here.
do
echo "$f is over 100KB and has not been accessed in over 30 days"
echo "Consider moving the file to archives."
foundone=true
done
if [ $foundone = false ]
then
echo "No files need archiving."
fi
# ==================And here is another alternative==================
# Places the part of the script that reads the variables
#+ within a code block, so they share the same subshell.
# Thank you, W.B.
find $HOME -type f -atime +30 -size 100k | {
foundone=false
while read f
do
echo "$f is over 100KB and has not been accessed in over 30 days"
echo "Consider moving the file to archives."
foundone=true
done
if ! $foundone
then
echo "No files need archiving."
fi
}
tail -f /var/log/messages | grep "$ERROR_MSG" &gt;&gt; error.log
# The "error.log" file will not have anything written to it.
# As Samuli Kaipiainen points out, this results from grep
#+ buffering its output.
# The fix is to add the "--line-buffered" parameter to grep.</pre>]
#!/bin/bash
# Call this script with at least 10 parameters, for example
# ./scriptname 1 2 3 4 5 6 7 8 9 10
MINPARAMS=10
echo
echo "The name of this script is \"$0\"."
# Adds ./ for current directory
echo "The name of this script is \"`basename $0`\"."
# Strips out path name info (see 'basename')
echo
if [ -n "$1" ] # Tested variable is quoted.
then
echo "Parameter #1 is $1" # Need quotes to escape #
fi
if [ -n "$2" ]
then
echo "Parameter #2 is $2"
fi
if [ -n "$3" ]
then
echo "Parameter #3 is $3"
fi
# ...
if [ -n "${10}" ] # Parameters &gt; $9 must be enclosed in {brackets}.
then
echo "Parameter #10 is ${10}"
fi
echo "-----------------------------------"
echo "All the command-line parameters are: "$*""
if [ $# -lt "$MINPARAMS" ]
then
echo
echo "This script needs at least $MINPARAMS command-line arguments!"
fi
echo
exit 0
args=$# # Number of args passed.
lastarg=${!args}
# Note: This is an *indirect reference* to $args ...
# Or: lastarg=${!#} (Thanks, Chris Monson.)
# This is an *indirect reference* to the $# variable.
# Note that lastarg=${!$#} doesn't work.
variable1_=$1_ # Rather than variable1=$1
# This will prevent an error, even if positional parameter is absent.
critical_argument01=$variable1_
# The extra character can be stripped off later, like so.
variable1=${variable1_/_/}
# Side effects only if $variable1_ begins with an underscore.
# This uses one of the parameter substitution templates discussed later.
# (Leaving out the replacement pattern results in a deletion.)
# A more straightforward way of dealing with this is
#+ to simply test whether expected positional parameters have been passed.
if [ -z $1 ]
then
exit $E_MISSING_POS_PARAM
fi
# However, as Fabian Kreutz points out,
#+ the above method may have unexpected side-effects.
# A better method is parameter substitution:
# ${1:-$DefaultVal}
# See the "Parameter Substition" section
#+ in the "Variables Revisited" chapter.
#!/bin/bash
# ex18.sh
# Does a 'whois domain-name' lookup on any of 3 alternate servers:
# ripe.net, cw.net, radb.net
# Place this script -- renamed 'wh' -- in /usr/local/bin
# Requires symbolic links:
# ln -s /usr/local/bin/wh /usr/local/bin/wh-ripe
# ln -s /usr/local/bin/wh /usr/local/bin/wh-apnic
# ln -s /usr/local/bin/wh /usr/local/bin/wh-tucows
E_NOARGS=75
if [ -z "$1" ]
then
echo "Usage: `basename $0` [domain-name]"
exit $E_NOARGS
fi
# Check script name and call proper server.
case `basename $0` in # Or: case ${0##*/} in
"wh" ) whois $1@whois.tucows.com;;
"wh-ripe" ) whois $1@whois.ripe.net;;
"wh-apnic" ) whois $1@whois.apnic.net;;
"wh-cw" ) whois $1@whois.cw.net;;
* ) echo "Usage: `basename $0` [domain-name]";;
esac
exit $?
#!/bin/bash
# shft.sh: Using 'shift' to step through all the positional parameters.
# Name this script something like shft.sh,
#+ and invoke it with some parameters.
#+ For example:
# sh shft.sh a b c def 83 barndoor
until [ -z "$1" ] # Until all parameters used up . . .
do
echo -n "$1 "
shift
done
echo # Extra linefeed.
# But, what happens to the "used-up" parameters?
echo "$2"
# Nothing echoes!
# When $2 shifts into $1 (and there is no $3 to shift into $2)
#+ then $2 remains empty.
# So, it is not a parameter *copy*, but a *move*.
exit
# See also the echo-params.sh script for a "shiftless"
#+ alternative method of stepping through the positional params.
#!/bin/bash
# shift-past.sh
shift 3 # Shift 3 positions.
# n=3; shift $n
# Has the same effect.
echo "$1"
exit 0
# ======================== #
$ sh shift-past.sh 1 2 3 4 5
4
# However, as Eleni Fragkiadaki, points out,
#+ attempting a 'shift' past the number of
#+ positional parameters ($#) returns an exit status of 1,
#+ and the positional parameters themselves do not change.
# This means possibly getting stuck in an endless loop. . . .
# For example:
# until [ -z "$1" ]
# do
# echo -n "$1 "
# shift 20 # If less than 20 pos params,
# done #+ then loop never ends!
#
# When in doubt, add a sanity check. . . .
# shift 20 || break
# ^^^^^^^^</pre>]
#!/bin/bash
# Exercising the 'date' command
echo "The number of days since the year's beginning is `date +%j`."
# Needs a leading '+' to invoke formatting.
# %j gives day of year.
echo "The number of seconds elapsed since 01/01/1970 is `date +%s`."
# %s yields number of seconds since "UNIX epoch" began,
#+ but how is this useful?
prefix=temp
suffix=$(date +%s) # The "+%s" option to 'date' is GNU-specific.
filename=$prefix.$suffix
echo "Temporary filename = $filename"
# It's great for creating "unique and random" temp filenames,
#+ even better than using $$.
# Read the 'date' man page for more formatting options.
exit 0
#!/bin/bash
# date-calc.sh
# Author: Nathan Coulter
# Used in ABS Guide with permission (thanks!).
MPHR=60 # Minutes per hour.
HPD=24 # Hours per day.
diff () {
printf '%s' $(( $(date -u -d"$TARGET" +%s) -
$(date -u -d"$CURRENT" +%s)))
# %d = day of month.
}
CURRENT=$(date -u -d '2007-09-01 17:30:24' '+%F %T.%N %Z')
TARGET=$(date -u -d'2007-12-25 12:30:00' '+%F %T.%N %Z')
# %F = full date, %T = %H:%M:%S, %N = nanoseconds, %Z = time zone.
printf '\nIn 2007, %s ' \
"$(date -d"$CURRENT +
$(( $(diff) /$MPHR /$MPHR /$HPD / 2 )) days" '+%d %B')"
# %B = name of month ^ halfway
printf 'was halfway between %s ' "$(date -d"$CURRENT" '+%d %B')"
printf 'and %s\n' "$(date -d"$TARGET" '+%d %B')"
printf '\nOn %s at %s, there were\n' \
$(date -u -d"$CURRENT" +%F) $(date -u -d"$CURRENT" +%T)
DAYS=$(( $(diff) / $MPHR / $MPHR / $HPD ))
CURRENT=$(date -d"$CURRENT +$DAYS days" '+%F %T.%N %Z')
HOURS=$(( $(diff) / $MPHR / $MPHR ))
CURRENT=$(date -d"$CURRENT +$HOURS hours" '+%F %T.%N %Z')
MINUTES=$(( $(diff) / $MPHR ))
CURRENT=$(date -d"$CURRENT +$MINUTES minutes" '+%F %T.%N %Z')
printf '%s days, %s hours, ' "$DAYS" "$HOURS"
printf '%s minutes, and %s seconds ' "$MINUTES" "$(diff)"
printf 'until Christmas Dinner!\n\n'
# Exercise:
# --------
# Rewrite the diff () function to accept passed parameters,
#+ rather than using global variables.
date +%N | sed -e 's/000$//' -e 's/^0//'
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
# Strip off leading and trailing zeroes, if present.
# Length of generated integer depends on
#+ how many zeroes stripped off.
# 115281032
# 63408725
# 394504284
date +%j
# Echoes day of the year (days elapsed since January 1).
date +%k%M
# Echoes hour and minute in 24-hour format, as a single digit string.
# The 'TZ' parameter permits overriding the default time zone.
date # Mon Mar 28 21:42:16 MST 2005
TZ=EST date # Mon Mar 28 23:42:16 EST 2005
# Thanks, Frank Kannemann and Pete Sjoberg, for the tip.
SixDaysAgo=$(date --date='6 days ago')
OneMonthAgo=$(date --date='1 month ago') # Four weeks back (not a month!)
OneYearAgo=$(date --date='1 year ago')
sleep 3 # Pauses 3 seconds.
sleep 3 h # Pauses 3 hours!
usleep 30 # Pauses 30 microseconds.</pre>]
COMMAND_OUTPUT &gt;
# Redirect stdout to a file.
# Creates the file if not present, otherwise overwrites it.
ls -lR &gt; dir-tree.list
# Creates a file containing a listing of the directory tree.
: &gt; filename
# The &gt; truncates file "filename" to zero length.
# If file not present, creates zero-length file (same effect as 'touch').
# The : serves as a dummy placeholder, producing no output.
&gt; filename
# The &gt; truncates file "filename" to zero length.
# If file not present, creates zero-length file (same effect as 'touch').
# (Same result as ": &gt;", above, but this does not work with some shells.)
COMMAND_OUTPUT &gt;&gt;
# Redirect stdout to a file.
# Creates the file if not present, otherwise appends to it.
# Single-line redirection commands (affect only the line they are on):
# --------------------------------------------------------------------
1&gt;filename
# Redirect stdout to file "filename."
1&gt;&gt;filename
# Redirect and append stdout to file "filename."
2&gt;filename
# Redirect stderr to file "filename."
2&gt;&gt;filename
# Redirect and append stderr to file "filename."
&&gt;filename
# Redirect both stdout and stderr to file "filename."
# This operator is now functional, as of Bash 4, final release.
M&gt;N
# "M" is a file descriptor, which defaults to 1, if not explicitly set.
# "N" is a filename.
# File descriptor "M" is redirect to file "N."
M&gt;&N
# "M" is a file descriptor, which defaults to 1, if not set.
# "N" is another file descriptor.
#==============================================================================
# Redirecting stdout, one line at a time.
LOGFILE=script.log
echo "This statement is sent to the log file, \"$LOGFILE\"." 1&gt;$LOGFILE
echo "This statement is appended to \"$LOGFILE\"." 1&gt;&gt;$LOGFILE
echo "This statement is also appended to \"$LOGFILE\"." 1&gt;&gt;$LOGFILE
echo "This statement is echoed to stdout, and will not appear in \"$LOGFILE\"."
# These redirection commands automatically "reset" after each line.
# Redirecting stderr, one line at a time.
ERRORFILE=script.errors
bad_command1 2&gt;$ERRORFILE # Error message sent to $ERRORFILE.
bad_command2 2&gt;&gt;$ERRORFILE # Error message appended to $ERRORFILE.
bad_command3 # Error message echoed to stderr,
#+ and does not appear in $ERRORFILE.
# These redirection commands also automatically "reset" after each line.
#=======================================================================
2&gt;&1
# Redirects stderr to stdout.
# Error messages get sent to same place as standard output.
&gt;&gt;filename 2&gt;&1
bad_command &gt;&gt;filename 2&gt;&1
# Appends both stdout and stderr to the file "filename" ...
2&gt;&1 | [command(s)]
bad_command 2&gt;&1 | awk '{print $5}' # found
# Sends stderr through a pipe.
# |& was added to Bash 4 as an abbreviation for 2&gt;&1 |.
i&gt;&j
# Redirects file descriptor <em>i</em> to <em>j</em>.
# All output of file pointed to by <em>i</em> gets sent to file pointed to by <em>j</em>.
&gt;&j
# Redirects, by default, file descriptor <em>1</em> (stdout) to <em>j</em>.
# All stdout gets sent to file pointed to by <em>j</em>.
0< FILENAME
< FILENAME
# Accept input from a file.
# Companion command to <span class="QUOTE">"&gt;"</span>, and often used in combination with it.
#
# grep search-word <filename
[j]<&gt;filename
# Open file "filename" for reading and writing,
#+ and assign file descriptor "j" to it.
# If "filename" does not exist, create it.
# If file descriptor "j" is not specified, default to fd 0, stdin.
#
# An application of this is writing at a specified place in a file.
echo 1234567890 &gt; File # Write string to "File".
exec 3<&gt; File # Open "File" and assign fd 3 to it.
read -n 4 <&3 # Read only 4 characters.
echo -n . &gt;&3 # Write a decimal point there.
exec 3&gt;&- # Close fd 3.
cat File # ==&gt; 1234.67890
# Random access, by golly.
|
# Pipe.
# General purpose process and command chaining tool.
# Similar to <span class="QUOTE">"&gt;"</span>, but more general in effect.
# Useful for chaining commands, scripts, files, and programs together.
cat *.txt | sort | uniq &gt; result-file
# Sorts the output of all the .txt files and deletes duplicate lines,
# finally saves results to <span class="QUOTE">"result-file"</span>.
command < input-file &gt; output-file
# Or the equivalent:
< input-file command &gt; output-file # Although this is non-standard.
command1 | command2 | command3 &gt; output-file
ls -yz &gt;&gt; command.log 2&gt;&1
# Capture result of illegal options "yz" in file "command.log."
# Because stderr is redirected to the file,
#+ any error messages will also be there.
# Note, however, that the following does *not* give the same result.
ls -yz 2&gt;&1 &gt;&gt; command.log
# Outputs an error message, but does not write to file.
# More precisely, the command output (in this case, null)
#+ writes to the file, but the error message goes only to stdout.
# If redirecting both stdout and stderr,
#+ the order of the commands makes a difference.
# Redirecting only stderr to a pipe.
exec 3&gt;&1 # Save current "value" of stdout.
ls -l 2&gt;&1 &gt;&3 3&gt;&- | grep bad 3&gt;&- # Close fd 3 for 'grep' (but not 'ls').
# ^^^^ ^^^^
exec 3&gt;&- # Now close it for the remainder of the script.
# Thanks, S.C.</pre>]
script_name=`basename $0`
echo "The name of this script is $script_name."
rm `cat filename` # <span class="QUOTE">"filename"</span> contains a list of files to delete.
#
# S. C. points out that "arg list too long" error might result.
# Better is xargs rm -- < filename
# ( -- covers those cases where <span class="QUOTE">"filename"</span> begins with a <span class="QUOTE">"-"</span> )
textfile_listing=`ls *.txt`
# Variable contains names of all *.txt files in current working directory.
echo $textfile_listing
textfile_listing2=$(ls *.txt) # The alternative form of command substitution.
echo $textfile_listing2
# Same result.
# A possible problem with putting a list of files into a single string
# is that a newline may creep in.
#
# A safer way to assign a list of files to a parameter is with an array.
# shopt -s nullglob # If no match, filename expands to nothing.
# textfile_listing=( *.txt )
#
# Thanks, S.C.
COMMAND `echo a b` # 2 args: a and b
COMMAND "`echo a b`" # 1 arg: "a b"
COMMAND `echo` # no arg
COMMAND "`echo`" # one empty arg
# Thanks, S.C.
# cd "`pwd`" # This should always work.
# However...
mkdir 'dir with trailing newline
'
cd 'dir with trailing newline
'
cd "`pwd`" # Error message:
# bash: cd: /tmp/file with trailing newline: No such file or directory
cd "$PWD" # Works fine.
old_tty_setting=$(stty -g) # Save old terminal setting.
echo "Hit a key "
stty -icanon -echo # Disable "canonical" mode for terminal.
# Also, disable *local* echo.
key=$(dd bs=1 count=1 2&gt; /dev/null) # Using 'dd' to get a keypress.
stty "$old_tty_setting" # Restore old setting.
echo "You hit ${#key} key." # ${#variable} = number of characters in $variable
#
# Hit any key except RETURN, and the output is "You hit 1 key."
# Hit RETURN, and it's "You hit 0 key."
# The newline gets eaten in the command substitution.
#Code snippet by Stéphane Chazelas.
dir_listing=`ls -l`
echo $dir_listing # unquoted
# Expecting a nicely ordered directory listing.
# However, what you get is:
# total 3 -rw-rw-r-- 1 bozo bozo 30 May 13 17:15 1.txt -rw-rw-r-- 1 bozo
# bozo 51 May 15 20:57 t2.sh -rwxr-xr-x 1 bozo bozo 217 Mar 5 21:13 wi.sh
# The newlines disappeared.
echo "$dir_listing" # quoted
# -rw-rw-r-- 1 bozo 30 May 13 17:15 1.txt
# -rw-rw-r-- 1 bozo 51 May 15 20:57 t2.sh
# -rwxr-xr-x 1 bozo 217 Mar 5 21:13 wi.sh
variable1=`<file1` # Set "variable1" to contents of "file1".
variable2=`cat file2` # Set "variable2" to contents of "file2".
# This, however, forks a new process,
#+ so the line of code executes slower than the above version.
# Note that the variables may contain embedded whitespace,
#+ or even (horrors), control characters.
# It is not necessary to explicitly assign a variable.
echo "` <$0`" # Echoes the script itself to stdout.
# Excerpts from system file, /etc/rc.d/rc.sysinit
#+ (on a Red Hat Linux installation)
if [ -f /fsckoptions ]; then
fsckoptions=`cat /fsckoptions`
...
fi
#
#
if [ -e "/proc/ide/${disk[$device]}/media" ] ; then
hdmedia=`cat /proc/ide/${disk[$device]}/media`
...
fi
#
#
if [ ! -n "`uname -r | grep -- "-"`" ]; then
ktag="`cat /proc/version`"
...
fi
#
#
if [ $usb = "1" ]; then
sleep 5
mouseoutput=`cat /proc/bus/usb/devices 2&gt;/dev/null|grep -E "^I.*Cls=03.*Prot=02"`
kbdoutput=`cat /proc/bus/usb/devices 2&gt;/dev/null|grep -E "^I.*Cls=03.*Prot=01"`
...
fi
#!/bin/bash
# stupid-script-tricks.sh: Don't try this at home, folks.
# From "Stupid Script Tricks," Volume I.
exit 99 ### Comment out this line if you dare.
dangerous_variable=`cat /boot/vmlinuz` # The compressed Linux kernel itself.
echo "string-length of \$dangerous_variable = ${#dangerous_variable}"
# string-length of $dangerous_variable = 794151
# (Newer kernels are bigger.)
# Does not give same count as 'wc -c /boot/vmlinuz'.
# echo "$dangerous_variable"
# Don't try this! It would hang the script.
# The document author is aware of no useful applications for
#+ setting a variable to the contents of a binary file.
exit 0
#!/bin/bash
# csubloop.sh: Setting a variable to the output of a loop.
variable1=`for i in 1 2 3 4 5
do
echo -n "$i" # The 'echo' command is critical
done` #+ to command substitution here.
echo "variable1 = $variable1" # variable1 = 12345
i=0
variable2=`while [ "$i" -lt 10 ]
do
echo -n "$i" # Again, the necessary 'echo'.
let "i += 1" # Increment.
done`
echo "variable2 = $variable2" # variable2 = 0123456789
# Demonstrates that it's possible to embed a loop
#+ inside a variable declaration.
exit 0
#include <stdio.h&gt;
/* "Hello, world." C program */
int main()
{
printf( "Hello, world.\n" );
return (0);
}
#!/bin/bash
# hello.sh
greeting=`./hello`
echo $greeting
output=$(sed -n /"$1"/p $file) # From "grp.sh" example.
# Setting a variable to the contents of a text file.
File_contents1=$(cat $file1)
File_contents2=$(<$file2) # Bash permits this also.
word_count=$( wc -w $(echo * | awk '{print $8}') )
#!/bin/bash
# agram2.sh
# Example of nested command substitution.
# Uses "anagram" utility
#+ that is part of the author's "yawl" word list package.
# http://ibiblio.org/pub/Linux/libs/yawl-0.3.2.tar.gz
# http://bash.deta.in/yawl-0.3.2.tar.gz
E_NOARGS=86
E_BADARG=87
MINLEN=7
if [ -z "$1" ]
then
echo "Usage $0 LETTERSET"
exit $E_NOARGS # Script needs a command-line argument.
elif [ ${#1} -lt $MINLEN ]
then
echo "Argument must have at least $MINLEN letters."
exit $E_BADARG
fi
FILTER='.......' # Must have at least 7 letters.
# 1234567
Anagrams=( $(echo $(anagram $1 | grep $FILTER) ) )
# $( $( nested command sub. ) )
# ( array assignment )
echo
echo "${#Anagrams[*]} 7+ letter anagrams found"
echo
echo ${Anagrams[0]} # First anagram.
echo ${Anagrams[1]} # Second anagram.
# Etc.
# echo "${Anagrams[*]}" # To list all the anagrams in a single line . . .
# Look ahead to the Arrays chapter for enlightenment on
#+ what's going on here.
# See also the agram.sh script for an exercise in anagram finding.
exit $?
word_count=` wc -w \`echo * | awk '{print $8}'\` `</pre>]
COMMAND <<InputComesFromHERE
...
...
...
InputComesFromHERE
command #1
command #2
...
interactive-program <<LimitString
command #1
command #2
...
LimitString
#!/bin/bash
wall <<zzz23EndOfMessagezzz23
E-mail your noontime orders for pizza to the system administrator.
(Add an extra dollar for anchovy or mushroom topping.)
# Additional message text goes here.
# Note: 'wall' prints comment lines.
zzz23EndOfMessagezzz23
# Could have been done more efficiently by
# wall <message-file
# However, embedding the message template in a script
#+ is a quick-and-dirty one-off solution.
exit
#!/bin/bash
# Noninteractive use of 'vi' to edit a file.
# Emulates 'sed'.
E_BADARGS=85
if [ -z "$1" ]
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS
fi
TARGETFILE=$1
# Insert 2 lines in file, then save.
#--------Begin here document-----------#
vi $TARGETFILE <<x23LimitStringx23
i
This is line 1 of the example file.
This is line 2 of the example file.
^[
ZZ
x23LimitStringx23
#----------End here document-----------#
# Note that ^[ above is a literal escape
#+ typed by Control-V <Esc&gt;.
# Bram Moolenaar points out that this may not work with 'vim'
#+ because of possible problems with terminal interaction.
exit
#!/bin/bash
# Replace all instances of "Smith" with "Jones"
#+ in files with a ".txt" filename suffix.
ORIGINAL=Smith
REPLACEMENT=Jones
for word in $(fgrep -l $ORIGINAL *.txt)
do
# -------------------------------------
ex $word <<EOF
:%s/$ORIGINAL/$REPLACEMENT/g
:wq
EOF
# :%s is the "ex" substitution command.
# :wq is write-and-quit.
# -------------------------------------
done
#!/bin/bash
# 'echo' is fine for printing single line messages,
#+ but somewhat problematic for for message blocks.
# A 'cat' here document overcomes this limitation.
cat <<End-of-message
-------------------------------------
This is line 1 of the message.
This is line 2 of the message.
This is line 3 of the message.
This is line 4 of the message.
This is the last line of the message.
-------------------------------------
End-of-message
# Replacing line 7, above, with
#+ cat &gt; $Newfile <<End-of-message
#+ ^^^^^^^^^^
#+ writes the output to the file $Newfile, rather than to stdout.
exit 0
#--------------------------------------------
# Code below disabled, due to "exit 0" above.
# S.C. points out that the following also works.
echo "-------------------------------------
This is line 1 of the message.
This is line 2 of the message.
This is line 3 of the message.
This is line 4 of the message.
This is the last line of the message.
-------------------------------------"
# However, text may not include double quotes unless they are escaped.
#!/bin/bash
# Same as previous example, but...
# The - option to a here document <<-
#+ suppresses leading tabs in the body of the document,
#+ but *not* spaces.
cat <<-ENDOFMESSAGE
This is line 1 of the message.
This is line 2 of the message.
This is line 3 of the message.
This is line 4 of the message.
This is the last line of the message.
ENDOFMESSAGE
# The output of the script will be flush left.
# Leading tab in each line will not show.
# Above 5 lines of "message" prefaced by a tab, not spaces.
# Spaces not affected by <<- .
# Note that this option has no effect on *embedded* tabs.
exit 0
#!/bin/bash
# Another 'cat' here document, using parameter substitution.
# Try it with no command-line parameters, ./scriptname
# Try it with one command-line parameter, ./scriptname Mortimer
# Try it with one two-word quoted command-line parameter,
# ./scriptname "Mortimer Jones"
CMDLINEPARAM=1 # Expect at least command-line parameter.
if [ $# -ge $CMDLINEPARAM ]
then
NAME=$1 # If more than one command-line param,
#+ then just take the first.
else
NAME="John Doe" # Default, if no command-line parameter.
fi
RESPONDENT="the author of this fine script"
cat <<Endofmessage
Hello, there, $NAME.
Greetings to you, $NAME, from $RESPONDENT.
# This comment shows up in the output (why?).
Endofmessage
# Note that the blank lines show up in the output.
# So does the comment.
exit
#!/bin/bash
# upload.sh
# Upload file pair (Filename.lsm, Filename.tar.gz)
#+ to incoming directory at Sunsite/UNC (ibiblio.org).
# Filename.tar.gz is the tarball itself.
# Filename.lsm is the descriptor file.
# Sunsite requires "lsm" file, otherwise will bounce contributions.
E_ARGERROR=85
if [ -z "$1" ]
then
echo "Usage: `basename $0` Filename-to-upload"
exit $E_ARGERROR
fi
Filename=`basename $1` # Strips pathname out of file name.
Server="ibiblio.org"
Directory="/incoming/Linux"
# These need not be hard-coded into script,
#+ but may instead be changed to command-line argument.
Password="your.e-mail.address" # Change above to suit.
ftp -n $Server <<End-Of-Session
# -n option disables auto-logon
user anonymous "$Password" # If this doesn't work, then try:
# quote user anonymous "$Password"
binary
bell # Ring 'bell' after each file transfer.
cd $Directory
put "$Filename.lsm"
put "$Filename.tar.gz"
bye
End-Of-Session
exit 0
#!/bin/bash
# A 'cat' here-document, but with parameter substitution disabled.
NAME="John Doe"
RESPONDENT="the author of this fine script"
cat <<'Endofmessage'
Hello, there, $NAME.
Greetings to you, $NAME, from $RESPONDENT.
Endofmessage
# No parameter substitution when the "limit string" is quoted or escaped.
# Either of the following at the head of the here document would have
#+ the same effect.
# cat <<"Endofmessage"
# cat <<\Endofmessage
# And, likewise:
cat <<"SpecialCharTest"
Directory listing would follow
if limit string were not quoted.
`ls -l`
Arithmetic expansion would take place
if limit string were not quoted.
$((5 + 3))
A a single backslash would echo
if limit string were not quoted.
\\
SpecialCharTest
exit
#!/bin/bash
# generate-script.sh
# Based on an idea by Albert Reiner.
OUTFILE=generated.sh # Name of the file to generate.
# -----------------------------------------------------------
# 'Here document containing the body of the generated script.
(
cat <<'EOF'
#!/bin/bash
echo "This is a generated shell script."
# Note that since we are inside a subshell,
#+ we can't access variables in the "outside" script.
echo "Generated file will be named: $OUTFILE"
# Above line will not work as normally expected
#+ because parameter expansion has been disabled.
# Instead, the result is literal output.
a=7
b=3
let "c = $a * $b"
echo "c = $c"
exit 0
EOF
) &gt; $OUTFILE
# -----------------------------------------------------------
# Quoting the 'limit string' prevents variable expansion
#+ within the body of the above 'here document.'
# This permits outputting literal strings in the output file.
if [ -f "$OUTFILE" ]
then
chmod 755 $OUTFILE
# Make the generated file executable.
else
echo "Problem in creating file: \"$OUTFILE\""
fi
# This method also works for generating
#+ C programs, Perl programs, Python programs, Makefiles,
#+ and the like.
exit 0
variable=$(cat <<SETVAR
This variable
runs over multiple lines.
SETVAR
)
echo "$variable"
#!/bin/bash
# here-function.sh
GetPersonalData ()
{
read firstname
read lastname
read address
read city
read state
read zipcode
} # This certainly appears to be an interactive function, but . . .
# Supply input to the above function.
GetPersonalData <<RECORD001
Bozo
Bozeman
2726 Nondescript Dr.
Bozeman
MT
21226
RECORD001
echo
echo "$firstname $lastname"
echo "$address"
echo "$city, $state $zipcode"
echo
exit 0
#!/bin/bash
: <<TESTVARIABLES
${HOSTNAME?}${USER?}${MAIL?} # Print error message if one of the variables not set.
TESTVARIABLES
exit $?
#!/bin/bash
# commentblock.sh
: <<COMMENTBLOCK
echo "This line will not echo."
This is a comment line missing the "#" prefix.
This is another comment line missing the "#" prefix.
&*@!!++=
The above line will cause no error message,
because the Bash interpreter will ignore it.
COMMENTBLOCK
echo "Exit value of above \"COMMENTBLOCK\" is $?." # 0
# No error shown.
echo
# The above technique also comes in useful for commenting out
#+ a block of working code for debugging purposes.
# This saves having to put a "#" at the beginning of each line,
#+ then having to go back and delete each "#" later.
# Note that the use of of colon, above, is optional.
echo "Just before commented-out code block."
# The lines of code between the double-dashed lines will not execute.
# ===================================================================
: <<DEBUGXXX
for file in *
do
cat "$file"
done
DEBUGXXX
# ===================================================================
echo "Just after commented-out code block."
exit 0
######################################################################
# Note, however, that if a bracketed variable is contained within
#+ the commented-out code block,
#+ then this could cause problems.
# for example:
#/!/bin/bash
: <<COMMENTBLOCK
echo "This line will not echo."
&*@!!++=
${foo_bar_bazz?}
$(rm -rf /tmp/foobar/)
$(touch my_build_directory/cups/Makefile)
COMMENTBLOCK
$ sh commented-bad.sh
commented-bad.sh: line 3: foo_bar_bazz: parameter null or not set
# The remedy for this is to strong-quote the 'COMMENTBLOCK' in line 49, above.
: <<'COMMENTBLOCK'
# Thank you, Kurt Pfeifle, for pointing this out.
#!/bin/bash
# self-document.sh: self-documenting script
# Modification of "colm.sh".
DOC_REQUEST=70
if [ "$1" = "-h" -o "$1" = "--help" ] # Request help.
then
echo; echo "Usage: $0 [directory-name]"; echo
sed --silent -e '/DOCUMENTATIONXX$/,/^DOCUMENTATIONXX$/p' "$0" |
sed -e '/DOCUMENTATIONXX$/d'; exit $DOC_REQUEST; fi
: <<DOCUMENTATIONXX
List the statistics of a specified directory in tabular format.
---------------------------------------------------------------
The command-line parameter gives the directory to be listed.
If no directory specified or directory specified cannot be read,
then list the current working directory.
DOCUMENTATIONXX
if [ -z "$1" -o ! -r "$1" ]
then
directory=.
else
directory="$1"
fi
echo "Listing of "$directory":"; echo
(printf "PERMISSIONS LINKS OWNER GROUP SIZE MONTH DAY HH:MM PROG-NAME\n" \
; ls -l "$directory" | sed 1d) | column -t
exit 0
DOC_REQUEST=70
if [ "$1" = "-h" -o "$1" = "--help" ] # Request help.
then # Use a "cat script" . . .
cat <<DOCUMENTATIONXX
List the statistics of a specified directory in tabular format.
---------------------------------------------------------------
The command-line parameter gives the directory to be listed.
If no directory specified or directory specified cannot be read,
then list the current working directory.
DOCUMENTATIONXX
exit $DOC_REQUEST
fi
#!/bin/bash
echo "----------------------------------------------------------------------"
cat <<LimitString
echo "This is line 1 of the message inside the here document."
echo "This is line 2 of the message inside the here document."
echo "This is the final line of the message inside the here document."
LimitString
#^^^^Indented limit string. Error! This script will not behave as expected.
echo "----------------------------------------------------------------------"
# These comments are outside the 'here document',
#+ and should not echo.
echo "Outside the here document."
exit 0
echo "This line had better not echo." # Follows an 'exit' command.
# This works.
cat <<!
Hello!
! Three more exclamations !!!
!
# But . . .
cat <<!
Hello!
Single exclamation point follows!
!
!
# Crashes with an error message.
# However, the following will work.
cat <<EOF
Hello!
Single exclamation point follows!
!
EOF
# It's safer to use a multi-character limit string.</pre>]
[]
#!/bin/bash
# escaped.sh: escaped characters
#############################################################
### First, let's show some basic escaped-character usage. ###
#############################################################
# Escaping a newline.
# ------------------
echo ""
echo "This will print
as two lines."
# This will print
# as two lines.
echo "This will print \
as one line."
# This will print as one line.
echo; echo
echo "============="
echo "\v\v\v\v" # Prints \v\v\v\v literally.
# Use the -e option with 'echo' to print escaped characters.
echo "============="
echo "VERTICAL TABS"
echo -e "\v\v\v\v" # Prints 4 vertical tabs.
echo "=============="
echo "QUOTATION MARK"
echo -e "\042" # Prints " (quote, octal ASCII character 42).
echo "=============="
# The $'\X' construct makes the -e option unnecessary.
echo; echo "NEWLINE and (maybe) BEEP"
echo $'\n' # Newline.
echo $'\a' # Alert (beep).
# May only flash, not beep, depending on terminal.
# We have seen $'\nnn" string expansion, and now . . .
# =================================================================== #
# Version 2 of Bash introduced the $'\nnn' string expansion construct.
# =================================================================== #
echo "Introducing the \$\' ... \' string-expansion construct . . . "
echo ". . . featuring more quotation marks."
echo $'\t \042 \t' # Quote (") framed by tabs.
# Note that '\nnn' is an octal value.
# It also works with hexadecimal values, in an $'\xhhh' construct.
echo $'\t \x22 \t' # Quote (") framed by tabs.
# Thank you, Greg Keraunen, for pointing this out.
# Earlier Bash versions allowed '\x022'.
echo
# Assigning ASCII characters to a variable.
# ----------------------------------------
quote=$'\042' # " assigned to a variable.
echo "$quote Quoted string $quote and this lies outside the quotes."
echo
# Concatenating ASCII chars in a variable.
triple_underline=$'\137\137\137' # 137 is octal ASCII code for '_'.
echo "$triple_underline UNDERLINE $triple_underline"
echo
ABC=$'\101\102\103\010' # 101, 102, 103 are octal A, B, C.
echo $ABC
echo
escape=$'\033' # 033 is octal for escape.
echo "\"escape\" echoes as $escape"
# no visible output.
echo
exit 0
#!/bin/bash
# Author: Sigurd Solaas, 20 Apr 2011
# Used in ABS Guide with permission.
# Requires version 4.2+ of Bash.
key="no value yet"
while true; do
clear
echo "Bash Extra Keys Demo. Keys to try:"
echo
echo "* Insert, Delete, Home, End, Page_Up and Page_Down"
echo "* The four arrow keys"
echo "* Tab, enter, escape, and space key"
echo "* The letter and number keys, etc."
echo
echo " d = show date/time"
echo " q = quit"
echo "================================"
echo
# Convert the separate home-key to home-key_num_7:
if [ "$key" = $'\x1b\x4f\x48' ]; then
key=$'\x1b\x5b\x31\x7e'
# Quoted string-expansion construct.
fi
# Convert the separate end-key to end-key_num_1.
if [ "$key" = $'\x1b\x4f\x46' ]; then
key=$'\x1b\x5b\x34\x7e'
fi
case "$key" in
$'\x1b\x5b\x32\x7e') # Insert
echo Insert Key
;;
$'\x1b\x5b\x33\x7e') # Delete
echo Delete Key
;;
$'\x1b\x5b\x31\x7e') # Home_key_num_7
echo Home Key
;;
$'\x1b\x5b\x34\x7e') # End_key_num_1
echo End Key
;;
$'\x1b\x5b\x35\x7e') # Page_Up
echo Page_Up
;;
$'\x1b\x5b\x36\x7e') # Page_Down
echo Page_Down
;;
$'\x1b\x5b\x41') # Up_arrow
echo Up arrow
;;
$'\x1b\x5b\x42') # Down_arrow
echo Down arrow
;;
$'\x1b\x5b\x43') # Right_arrow
echo Right arrow
;;
$'\x1b\x5b\x44') # Left_arrow
echo Left arrow
;;
$'\x09') # Tab
echo Tab Key
;;
$'\x0a') # Enter
echo Enter Key
;;
$'\x1b') # Escape
echo Escape Key
;;
$'\x20') # Space
echo Space Key
;;
d)
date
;;
q)
echo Time to quit...
echo
exit 0
;;
*)
echo You pressed: \'"$key"\'
;;
esac
echo
echo "================================"
unset K1 K2 K3
read -s -N1 -p "Press a key: "
K1="$REPLY"
read -s -N2 -t 0.001
K2="$REPLY"
read -s -N1 -t 0.001
K3="$REPLY"
key="$K1$K2$K3"
done
exit $?
echo "Hello" # Hello
echo "\"Hello\" ... he said." # "Hello" ... he said.
echo "\$variable01" # $variable01
echo "The book cost \$7.98." # The book cost $7.98.
echo "\\" # Results in \
# Whereas . . .
echo "\" # Invokes secondary prompt from the command-line.
# In a script, gives an error message.
# However . . .
echo '\' # Results in \
# Simple escaping and quoting
echo \z # z
echo \\z # \z
echo '\z' # \z
echo '\\z' # \\z
echo "\z" # \z
echo "\\z" # \z
# Command substitution
echo `echo \z` # z
echo `echo \\z` # z
echo `echo \\\z` # \z
echo `echo \\\\z` # \z
echo `echo \\\\\\z` # \z
echo `echo \\\\\\\z` # \\z
echo `echo "\z"` # \z
echo `echo "\\z"` # \z
# Here document
cat <<EOF
\z
EOF # \z
cat <<EOF
\\z
EOF # \z
# These examples supplied by Stéphane Chazelas.
variable=\
echo "$variable"
# Will not work - gives an error message:
# test.sh: : command not found
# A "naked" escape cannot safely be assigned to a variable.
#
# What actually happens here is that the "\" escapes the newline and
#+ the effect is variable=echo "$variable"
#+ invalid variable assignment
variable=\
23skidoo
echo "$variable" # 23skidoo
# This works, since the second line
#+ is a valid variable assignment.
variable=\
# \^ escape followed by space
echo "$variable" # space
variable=\\
echo "$variable" # \
variable=\\\
echo "$variable"
# Will not work - gives an error message:
# test.sh: \: command not found
#
# First escape escapes second one, but the third one is left "naked",
#+ with same result as first instance, above.
variable=\\\\
echo "$variable" # \\
# Second and fourth escapes escaped.
# This is o.k.
file_list="/bin/cat /bin/gzip /bin/more /usr/bin/less /usr/bin/emacs-20.7"
# List of files as argument(s) to a command.
# Add two files to the list, and list all.
ls -l /usr/X11R6/bin/xsetroot /sbin/dump $file_list
echo "-------------------------------------------------------------------------"
# What happens if we escape a couple of spaces?
ls -l /usr/X11R6/bin/xsetroot\ /sbin/dump\ $file_list
# Error: the first three files concatenated into a single argument to 'ls -l'
# because the two escaped spaces prevent argument (word) splitting.
(cd /source/directory && tar cf - . ) | \
(cd /dest/directory && tar xpvf -)
# Repeating Alan Cox's directory tree copy command,
# but split into two lines for increased legibility.
# As an alternative:
tar cf - -C /source/directory . |
tar xpvf - -C /dest/directory
# See note below.
# (Thanks, Stéphane Chazelas.)
echo "foo
bar"
#foo
#bar
echo
echo 'foo
bar' # No difference yet.
#foo
#bar
echo
echo foo\
bar # Newline escaped.
#foobar
echo
echo "foo\
bar" # Same here, as \ still interpreted as escape within weak quotes.
#foobar
echo
echo 'foo\
bar' # Escape character \ taken literally because of strong quoting.
#foo\
#bar
# Examples suggested by Stéphane Chazelas.</pre>]
From thegrendel@theriver.com Sat Jun 10 09:05:33 2000 -0700
Date: Sat, 10 Jun 2000 09:05:28 -0700 (MST)
From: "M. Leo Cooper" <thegrendel@theriver.com&gt;
X-Sender: thegrendel@localhost
To: ldp-discuss@lists.linuxdoc.org
Subject: Permission to submit HOWTO
Dear HOWTO Coordinator,
I am working on and would like to submit to the LDP a HOWTO on the subject
of "Bash Scripting" (shell scripting, using 'bash'). As it happens,
I have been writing this document, off and on, for about the last eight
months or so, and I could produce a first draft in ASCII text format in
a matter of just a few more days.
I began writing this out of frustration at being unable to find a
decent book on shell scripting. I managed to locate some pretty good
articles on various aspects of scripting, but nothing like a complete,
beginning-to-end tutorial. Well, in keeping with my philosophy, if all
else fails, do it yourself.
As it stands, this proposed "Bash-Scripting HOWTO" would serve as a
combination tutorial and reference, with the heavier emphasis on the
tutorial. It assumes Linux experience, but only a very basic level
of programming skills. Interspersed with the text are 79 illustrative
example scripts of varying complexity, all liberally commented. There
are even exercises for the reader.
At this stage, I'm up to 18,000+ words (124k), and that's over 50 pages of
text (whew!).
I haven't mentioned that I've previously authored an LDP HOWTO, the
"Software-Building HOWTO", which I wrote in Linuxdoc/SGML. I don't know
if I could handle Docbook/SGML, and I'm glad you have volunteers to do
the conversion. You people seem to have gotten on a more organized basis
these last few months. Working with Greg Hankins and Tim Bynum was nice,
but a professional team is even nicer.
Anyhow, please advise.
Mendel Cooper
thegrendel@theriver.com</pre>]
function_name $arg1 $arg2
#!/bin/bash
# Functions and parameters
DEFAULT=default # Default param value.
func2 () {
if [ -z "$1" ] # Is parameter #1 zero length?
then
echo "-Parameter #1 is zero length.-" # Or no parameter passed.
else
echo "-Parameter #1 is \"$1\".-"
fi
variable=${1-$DEFAULT} # What does
echo "variable = $variable" #+ parameter substitution show?
# ---------------------------
# It distinguishes between
#+ no param and a null param.
if [ "$2" ]
then
echo "-Parameter #2 is \"$2\".-"
fi
return 0
}
echo
echo "Nothing passed."
func2 # Called with no params
echo
echo "Zero-length parameter passed."
func2 "" # Called with zero-length param
echo
echo "Null parameter passed."
func2 "$uninitialized_param" # Called with uninitialized param
echo
echo "One parameter passed."
func2 first # Called with one param
echo
echo "Two parameters passed."
func2 first second # Called with two params
echo
echo "\"\" \"second\" passed."
func2 "" second # Called with zero-length first parameter
echo # and ASCII string as a second one.
exit 0
#!/bin/bash
# func-cmdlinearg.sh
# Call this script with a command-line argument,
#+ something like $0 arg1.
func ()
{
echo "$1" # Echoes first arg passed to the function.
} # Does a command-line arg qualify?
echo "First call to function: no arg passed."
echo "See if command-line arg is seen."
func
# No! Command-line arg not seen.
echo "============================================================"
echo
echo "Second call to function: command-line arg passed explicitly."
func $1
# Now it's seen!
exit 0
#!/bin/bash
# ind-func.sh: Passing an indirect reference to a function.
echo_var ()
{
echo "$1"
}
message=Hello
Hello=Goodbye
echo_var "$message" # Hello
# Now, let's pass an indirect reference to the function.
echo_var "${!message}" # Goodbye
echo "-------------"
# What happens if we change the contents of "hello" variable?
Hello="Hello, again!"
echo_var "$message" # Hello
echo_var "${!message}" # Hello, again!
exit 0
#!/bin/bash
# dereference.sh
# Dereferencing parameter passed to a function.
# Script by Bruce W. Clare.
dereference ()
{
y=\$"$1" # Name of variable (not value!).
echo $y # $Junk
x=`eval "expr \"$y\" "`
echo $1=$x
eval "$1=\"Some Different Text \"" # Assign new value.
}
Junk="Some Text"
echo $Junk "before" # Some Text before
dereference Junk
echo $Junk "after" # Some Different Text after
exit 0
#!/bin/bash
# ref-params.sh: Dereferencing a parameter passed to a function.
# (Complex Example)
ITERATIONS=3 # How many times to get input.
icount=1
my_read () {
# Called with my_read varname,
#+ outputs the previous value between brackets as the default value,
#+ then asks for a new value.
local local_var
echo -n "Enter a value "
eval 'echo -n "[$'$1'] "' # Previous value.
# eval echo -n "[\$$1] " # Easier to understand,
#+ but loses trailing space in user prompt.
read local_var
[ -n "$local_var" ] && eval $1=\$local_var
# "And-list": if "local_var" then set "$1" to its value.
}
echo
while [ "$icount" -le "$ITERATIONS" ]
do
my_read var
echo "Entry #$icount = $var"
let "icount += 1"
echo
done
# Thanks to Stephane Chazelas for providing this instructive example.
exit 0
#!/bin/bash
# max.sh: Maximum of two integers.
E_PARAM_ERR=250 # If less than 2 params passed to function.
EQUAL=251 # Return value if both params equal.
# Error values out of range of any
#+ params that might be fed to the function.
max2 () # Returns larger of two numbers.
{ # Note: numbers compared must be less than 250.
if [ -z "$2" ]
then
return $E_PARAM_ERR
fi
if [ "$1" -eq "$2" ]
then
return $EQUAL
else
if [ "$1" -gt "$2" ]
then
return $1
else
return $2
fi
fi
}
max2 33 34
return_val=$?
if [ "$return_val" -eq $E_PARAM_ERR ]
then
echo "Need to pass two parameters to the function."
elif [ "$return_val" -eq $EQUAL ]
then
echo "The two numbers are equal."
else
echo "The larger of the two numbers is $return_val."
fi
exit 0
# Exercise (easy):
# ---------------
# Convert this to an interactive script,
#+ that is, have the script ask for input (two numbers).
count_lines_in_etc_passwd()
{
[[ -r /etc/passwd ]] && REPLY=$(echo $(wc -l < /etc/passwd))
# If /etc/passwd is readable, set REPLY to line count.
# Returns both a parameter value and status information.
# The 'echo' seems unnecessary, but . . .
#+ it removes excess whitespace from the output.
}
if count_lines_in_etc_passwd
then
echo "There are $REPLY lines in /etc/passwd."
else
echo "Cannot count lines in /etc/passwd."
fi
# Thanks, S.C.
#!/bin/bash
# Arabic number to Roman numeral conversion
# Range: 0 - 200
# It's crude, but it works.
# Extending the range and otherwise improving the script is left as an exercise.
# Usage: roman number-to-convert
LIMIT=200
E_ARG_ERR=65
E_OUT_OF_RANGE=66
if [ -z "$1" ]
then
echo "Usage: `basename $0` number-to-convert"
exit $E_ARG_ERR
fi
num=$1
if [ "$num" -gt $LIMIT ]
then
echo "Out of range!"
exit $E_OUT_OF_RANGE
fi
to_roman () # Must declare function before first call to it.
{
number=$1
factor=$2
rchar=$3
let "remainder = number - factor"
while [ "$remainder" -ge 0 ]
do
echo -n $rchar
let "number -= factor"
let "remainder = number - factor"
done
return $number
# Exercises:
# ---------
# 1) Explain how this function works.
# Hint: division by successive subtraction.
# 2) Extend to range of the function.
# Hint: use "echo" and command-substitution capture.
}
to_roman $num 100 C
num=$?
to_roman $num 90 LXXXX
num=$?
to_roman $num 50 L
num=$?
to_roman $num 40 XL
num=$?
to_roman $num 10 X
num=$?
to_roman $num 9 IX
num=$?
to_roman $num 5 V
num=$?
to_roman $num 4 IV
num=$?
to_roman $num 1 I
# Successive calls to conversion function!
# Is this really necessary??? Can it be simplified?
echo
exit
#!/bin/bash
# return-test.sh
# The largest positive value a function can return is 255.
return_test () # Returns whatever passed to it.
{
return $1
}
return_test 27 # o.k.
echo $? # Returns 27.
return_test 255 # Still o.k.
echo $? # Returns 255.
return_test 257 # Error!
echo $? # Returns 1 (return code for miscellaneous error).
# =========================================================
return_test -151896 # Do large negative numbers work?
echo $? # Will this return -151896?
# No! It returns 168.
# Version of Bash before 2.05b permitted
#+ large negative integer return values.
# It happened to be a useful feature.
# Newer versions of Bash unfortunately plug this loophole.
# This may break older scripts.
# Caution!
# =========================================================
exit 0
Return_Val= # Global variable to hold oversize return value of function.
alt_return_test ()
{
fvar=$1
Return_Val=$fvar
return # Returns 0 (success).
}
alt_return_test 1
echo $? # 0
echo "return value = $Return_Val" # 1
alt_return_test 256
echo "return value = $Return_Val" # 256
alt_return_test 257
echo "return value = $Return_Val" # 257
alt_return_test 25701
echo "return value = $Return_Val" #25701
#!/bin/bash
# max2.sh: Maximum of two LARGE integers.
# This is the previous "max.sh" example,
#+ modified to permit comparing large integers.
EQUAL=0 # Return value if both params equal.
E_PARAM_ERR=-99999 # Not enough params passed to function.
# ^^^^^^ Out of range of any params that might be passed.
max2 () # "Returns" larger of two numbers.
{
if [ -z "$2" ]
then
echo $E_PARAM_ERR
return
fi
if [ "$1" -eq "$2" ]
then
echo $EQUAL
return
else
if [ "$1" -gt "$2" ]
then
retval=$1
else
retval=$2
fi
fi
echo $retval # Echoes (to stdout), rather than returning value.
# Why?
}
return_val=$(max2 33001 33997)
# ^^^^ Function name
# ^^^^^ ^^^^^ Params passed
# This is actually a form of command substitution:
#+ treating a function as if it were a command,
#+ and assigning the stdout of the function to the variable "return_val."
# ========================= OUTPUT ========================
if [ "$return_val" -eq "$E_PARAM_ERR" ]
then
echo "Error in parameters passed to comparison function!"
elif [ "$return_val" -eq "$EQUAL" ]
then
echo "The two numbers are equal."
else
echo "The larger of the two numbers is $return_val."
fi
# =========================================================
exit 0
# Exercises:
# ---------
# 1) Find a more elegant way of testing
#+ the parameters passed to the function.
# 2) Simplify the if/then structure at "OUTPUT."
# 3) Rewrite the script to take input from command-line parameters.
month_length () # Takes month number as an argument.
{ # Returns number of days in month.
monthD="31 28 31 30 31 30 31 31 30 31 30 31" # Declare as local?
echo "$monthD" | awk '{ print $'"${1}"' }' # Tricky.
# ^^^^^^^^^
# Parameter passed to function ($1 -- month number), then to awk.
# Awk sees this as "print $1 . . . print $12" (depending on month number)
# Template for passing a parameter to embedded awk script:
# $'"${script_parameter}"'
# Here's a slightly simpler awk construct:
# echo $monthD | awk -v month=$1 '{print $(month)}'
# Uses the -v awk option, which assigns a variable value
#+ prior to execution of the awk program block.
# Thank you, Rich.
# Needs error checking for correct parameter range (1-12)
#+ and for February in leap year.
}
# ----------------------------------------------
# Usage example:
month=4 # April, for example (4th month).
days_in=$(month_length $month)
echo $days_in # 30
# ----------------------------------------------
#!/bin/bash
# realname.sh
#
# From username, gets "real name" from /etc/passwd.
ARGCOUNT=1 # Expect one arg.
E_WRONGARGS=85
file=/etc/passwd
pattern=$1
if [ $# -ne "$ARGCOUNT" ]
then
echo "Usage: `basename $0` USERNAME"
exit $E_WRONGARGS
fi
file_excerpt () # Scan file for pattern,
{ #+ then print relevant portion of line.
while read line # "while" does not necessarily need [ condition ]
do
echo "$line" | grep $1 | awk -F":" '{ print $5 }'
# Have awk use ":" delimiter.
done
} <$file # Redirect into function's stdin.
file_excerpt $pattern
# Yes, this entire script could be reduced to
# grep PATTERN /etc/passwd | awk -F":" '{ print $5 }'
# or
# awk -F: '/PATTERN/ {print $5}'
# or
# awk -F: '($1 == "username") { print $5 }' # real name from username
# However, it might not be as instructive.
exit 0
# Instead of:
Function ()
{
...
} < file
# Try this:
Function ()
{
{
...
} < file
}
# Similarly,
Function () # This works.
{
{
echo $*
} | tr a b
}
Function () # This doesn't work.
{
echo $*
} | tr a b # A nested code block is mandatory here.
# Thanks, S.C.</pre>]
[]
#!/bin/bash
# redir2.sh
if [ -z "$1" ]
then
Filename=names.data # Default, if no filename specified.
else
Filename=$1
fi
#+ Filename=${1:-names.data}
# can replace the above test (parameter substitution).
count=0
echo
while [ "$name" != Smith ] # Why is variable $name in quotes?
do
read name # Reads from $Filename, rather than stdin.
echo $name
let "count += 1"
done <"$Filename" # Redirects stdin to file $Filename.
# ^^^^^^^^^^^^
echo; echo "$count names read"; echo
exit 0
# Note that in some older shell scripting languages,
#+ the redirected loop would run as a subshell.
# Therefore, $count would return 0, the initialized value outside the loop.
# Bash and ksh avoid starting a subshell *whenever possible*,
#+ so that this script, for example, runs correctly.
# (Thanks to Heiner Steven for pointing this out.)
# However . . .
# Bash *can* sometimes start a subshell in a PIPED "while-read" loop,
#+ as distinct from a REDIRECTED "while" loop.
abc=hi
echo -e "1\n2\n3" | while read l
do abc="$l"
echo $abc
done
echo $abc
# Thanks, Bruno de Oliveira Schneider, for demonstrating this
#+ with the above snippet of code.
# And, thanks, Brian Onn, for correcting an annotation error.
#!/bin/bash
# This is an alternate form of the preceding script.
# Suggested by Heiner Steven
#+ as a workaround in those situations when a redirect loop
#+ runs as a subshell, and therefore variables inside the loop
# +do not keep their values upon loop termination.
if [ -z "$1" ]
then
Filename=names.data # Default, if no filename specified.
else
Filename=$1
fi
exec 3<&0 # Save stdin to file descriptor 3.
exec 0<"$Filename" # Redirect standard input.
count=0
echo
while [ "$name" != Smith ]
do
read name # Reads from redirected stdin ($Filename).
echo $name
let "count += 1"
done # Loop reads from file $Filename
#+ because of line 20.
# The original version of this script terminated the "while" loop with
#+ done <"$Filename"
# Exercise:
# Why is this unnecessary?
exec 0<&3 # Restore old stdin.
exec 3<&- # Close temporary fd 3.
echo; echo "$count names read"; echo
exit 0
#!/bin/bash
# Same as previous example, but with "until" loop.
if [ -z "$1" ]
then
Filename=names.data # Default, if no filename specified.
else
Filename=$1
fi
# while [ "$name" != Smith ]
until [ "$name" = Smith ] # Change != to =.
do
read name # Reads from $Filename, rather than stdin.
echo $name
done <"$Filename" # Redirects stdin to file $Filename.
# ^^^^^^^^^^^^
# Same results as with "while" loop in previous example.
exit 0
#!/bin/bash
if [ -z "$1" ]
then
Filename=names.data # Default, if no filename specified.
else
Filename=$1
fi
line_count=`wc $Filename | awk '{ print $1 }'`
# Number of lines in target file.
#
# Very contrived and kludgy, nevertheless shows that
#+ it's possible to redirect stdin within a "for" loop...
#+ if you're clever enough.
#
# More concise is line_count=$(wc -l < "$Filename")
for name in `seq $line_count` # Recall that "seq" prints sequence of numbers.
# while [ "$name" != Smith ] -- more complicated than a "while" loop --
do
read name # Reads from $Filename, rather than stdin.
echo $name
if [ "$name" = Smith ] # Need all this extra baggage here.
then
break
fi
done <"$Filename" # Redirects stdin to file $Filename.
# ^^^^^^^^^^^^
exit 0
#!/bin/bash
if [ -z "$1" ]
then
Filename=names.data # Default, if no filename specified.
else
Filename=$1
fi
Savefile=$Filename.new # Filename to save results in.
FinalName=Jonah # Name to terminate "read" on.
line_count=`wc $Filename | awk '{ print $1 }'` # Number of lines in target file.
for name in `seq $line_count`
do
read name
echo "$name"
if [ "$name" = "$FinalName" ]
then
break
fi
done < "$Filename" &gt; "$Savefile" # Redirects stdin to file $Filename,
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^ and saves it to backup file.
exit 0
#!/bin/bash
if [ -z "$1" ]
then
Filename=names.data # Default, if no filename specified.
else
Filename=$1
fi
TRUE=1
if [ "$TRUE" ] # if true and if : also work.
then
read name
echo $name
fi <"$Filename"
# ^^^^^^^^^^^^
# Reads only first line of file.
# An "if/then" test has no way of iterating unless embedded in a loop.
exit 0
Aristotle
Arrhenius
Belisarius
Capablanca
Dickens
Euler
Goethe
Hegel
Jonah
Laplace
Maroczy
Purcell
Schmidt
Schopenhauer
Semmelweiss
Smith
Steinmetz
Tukhashevsky
Turing
Venn
Warshawski
Znosko-Borowski
# This is a data file for
#+ "redir2.sh", "redir3.sh", "redir4.sh", "redir4a.sh", "redir5.sh".
# This example by Albert Siersema
# Used with permission (thanks!).
function doesOutput()
# Could be an external command too, of course.
# Here we show you can use a function as well.
{
ls -al *.jpg | awk '{print $5,$9}'
}
nr=0 # We want the while loop to be able to manipulate these and
totalSize=0 #+ to be able to see the changes after the 'while' finished.
while read fileSize fileName ; do
echo "$fileName is $fileSize bytes"
let nr++
totalSize=$((totalSize+fileSize)) # Or: "let totalSize+=fileSize"
done<<EOF
$(doesOutput)
EOF
echo "$nr files totaling $totalSize bytes"</pre>]
[]
#!/bin/bash
# c-vars.sh
# Manipulating a variable, C-style, using the (( ... )) construct.
echo
(( a = 23 )) # Setting a value, C-style,
#+ with spaces on both sides of the "=".
echo "a (initial value) = $a" # 23
(( a++ )) # Post-increment 'a', C-style.
echo "a (after a++) = $a" # 24
(( a-- )) # Post-decrement 'a', C-style.
echo "a (after a--) = $a" # 23
(( ++a )) # Pre-increment 'a', C-style.
echo "a (after ++a) = $a" # 24
(( --a )) # Pre-decrement 'a', C-style.
echo "a (after --a) = $a" # 23
echo
########################################################
# Note that, as in C, pre- and post-decrement operators
#+ have different side-effects.
n=1; let --n && echo "True" || echo "False" # False
n=1; let n-- && echo "True" || echo "False" # True
# Thanks, Jeroen Domburg.
########################################################
echo
(( t = a<45?7:11 )) # C-style trinary operator.
# ^ ^ ^
echo "If a < 45, then t = 7, else t = 11." # a = 23
echo "t = $t " # t = 7
echo
# -----------------
# Easter Egg alert!
# -----------------
# Chet Ramey seems to have snuck a bunch of undocumented C-style
#+ constructs into Bash (actually adapted from ksh, pretty much).
# In the Bash docs, Ramey calls (( ... )) shell arithmetic,
#+ but it goes far beyond that.
# Sorry, Chet, the secret is out.
# See also "for" and "while" loops using the (( ... )) construct.
# These work only with version 2.04 or later of Bash.
exit</pre>]
#!/bin/bash
# test-cgi.sh
# by Michael Zick
# Used with permission
# May have to change the location for your site.
# (At the ISP's servers, Bash may not be in the usual place.)
# Other places: /usr/bin or /usr/local/bin
# Might even try it without any path in sha-bang.
# Disable filename globbing.
set -f
# Header tells browser what to expect.
echo Content-type: text/plain
echo
echo CGI/1.0 test script report:
echo
echo environment settings:
set
echo
echo whereis bash?
whereis bash
echo
echo who are we?
echo ${BASH_VERSINFO[*]}
echo
echo argc is $#. argv is "$*".
echo
# CGI/1.0 expected environment variables.
echo SERVER_SOFTWARE = $SERVER_SOFTWARE
echo SERVER_NAME = $SERVER_NAME
echo GATEWAY_INTERFACE = $GATEWAY_INTERFACE
echo SERVER_PROTOCOL = $SERVER_PROTOCOL
echo SERVER_PORT = $SERVER_PORT
echo REQUEST_METHOD = $REQUEST_METHOD
echo HTTP_ACCEPT = "$HTTP_ACCEPT"
echo PATH_INFO = "$PATH_INFO"
echo PATH_TRANSLATED = "$PATH_TRANSLATED"
echo SCRIPT_NAME = "$SCRIPT_NAME"
echo QUERY_STRING = "$QUERY_STRING"
echo REMOTE_HOST = $REMOTE_HOST
echo REMOTE_ADDR = $REMOTE_ADDR
echo REMOTE_USER = $REMOTE_USER
echo AUTH_TYPE = $AUTH_TYPE
echo CONTENT_TYPE = $CONTENT_TYPE
echo CONTENT_LENGTH = $CONTENT_LENGTH
exit 0
# Here document to give short instructions.
:<<-'_test_CGI_'
1) Drop this in your http://domain.name/cgi-bin directory.
2) Then, open http://domain.name/cgi-bin/test-cgi.sh.
_test_CGI_
#!/bin/bash
# ip-addresses.sh
# List the IP addresses your computer is connected to.
# Inspired by Greg Bledsoe's ddos.sh script,
# Linux Journal, 09 March 2011.
# URL:
# http://www.linuxjournal.com/content/back-dead-simple-bash-complex-ddos
# Greg licensed his script under the GPL2,
#+ and as a derivative, this script is likewise GPL2.
connection_type=TCP # Also try UDP.
field=2 # Which field of the output we're interested in.
no_match=LISTEN # Filter out records containing this. Why?
lsof_args=-ni # -i lists Internet-associated files.
# -n preserves numerical IP addresses.
# What happens without the -n option? Try it.
router="[0-9][0-9][0-9][0-9][0-9]-&gt;"
# Delete the router info.
lsof "$lsof_args" | grep $connection_type | grep -v "$no_match" |
awk '{print $9}' | cut -d : -f $field | sort | uniq |
sed s/"^$router"//
# Bledsoe's script assigns the output of a filtered IP list,
# (similar to lines 19-22, above) to a variable.
# He checks for multiple connections to a single IP address,
# then uses:
#
# iptables -I INPUT -s $ip -p tcp -j REJECT --reject-with tcp-reset
#
# ... within a 60-second delay loop to bounce packets from DDOS attacks.
# Exercise:
# --------
# Use the 'iptables' command to extend this script
#+ to reject connection attempts from well-known spammer IP domains.</pre>]
#!/bin/bash
# subshell-test.sh
(
# Inside parentheses, and therefore a subshell . . .
while [ 1 ] # Endless loop.
do
echo "Subshell running . . ."
done
)
# Script will run forever,
#+ or at least until terminated by a Ctl-C.
exit $? # End of script (but will never get here).
Now, run the script:
sh subshell-test.sh
And, while the script is running, from a different xterm:
ps -ef | grep subshell-test.sh
UID PID PPID C STIME TTY TIME CMD
500 2698 2502 0 14:26 pts/4 00:00:00 sh subshell-test.sh
500 2699 2698 21 14:26 pts/4 00:00:24 sh subshell-test.sh
^^^^
Analysis:
PID 2698, the script, launched PID 2699, the subshell.
Note: The "UID ..." line would be filtered out by the "grep" command,
but is shown here for illustrative purposes.
#!/bin/bash
# subshell.sh
echo
echo "We are outside the subshell."
echo "Subshell level OUTSIDE subshell = $BASH_SUBSHELL"
# Bash, version 3, adds the new $BASH_SUBSHELL variable.
echo; echo
outer_variable=Outer
global_variable=
# Define global variable for "storage" of
#+ value of subshell variable.
(
echo "We are inside the subshell."
echo "Subshell level INSIDE subshell = $BASH_SUBSHELL"
inner_variable=Inner
echo "From inside subshell, \"inner_variable\" = $inner_variable"
echo "From inside subshell, \"outer\" = $outer_variable"
global_variable="$inner_variable" # Will this allow "exporting"
#+ a subshell variable?
)
echo; echo
echo "We are outside the subshell."
echo "Subshell level OUTSIDE subshell = $BASH_SUBSHELL"
echo
if [ -z "$inner_variable" ]
then
echo "inner_variable undefined in main body of shell"
else
echo "inner_variable defined in main body of shell"
fi
echo "From main body of shell, \"inner_variable\" = $inner_variable"
# $inner_variable will show as blank (uninitialized)
#+ because variables defined in a subshell are "local variables".
# Is there a remedy for this?
echo "global_variable = "$global_variable"" # Why doesn't this work?
echo
# =======================================================================
# Additionally ...
echo "-----------------"; echo
var=41 # Global variable.
( let "var+=1"; echo "\$var INSIDE subshell = $var" ) # 42
echo "\$var OUTSIDE subshell = $var" # 41
# Variable operations inside a subshell, even to a GLOBAL variable
#+ do not affect the value of the variable outside the subshell!
exit 0
# Question:
# --------
# Once having exited a subshell,
#+ is there any way to reenter that very same subshell
#+ to modify or access the subshell variables?
echo " \$BASH_SUBSHELL outside subshell = $BASH_SUBSHELL" # 0
( echo " \$BASH_SUBSHELL inside subshell = $BASH_SUBSHELL" ) # 1
( ( echo " \$BASH_SUBSHELL inside nested subshell = $BASH_SUBSHELL" ) ) # 2
# ^ ^ *** nested *** ^ ^
echo
echo " \$SHLVL outside subshell = $SHLVL" # 3
( echo " \$SHLVL inside subshell = $SHLVL" ) # 3 (No change!)
#!/bin/bash
# allprofs.sh: Print all user profiles.
# This script written by Heiner Steven, and modified by the document author.
FILE=.bashrc # File containing user profile,
#+ was ".profile" in original script.
for home in `awk -F: '{print $6}' /etc/passwd`
do
[ -d "$home" ] || continue # If no home directory, go to next.
[ -r "$home" ] || continue # If not readable, go to next.
(cd $home; [ -e $FILE ] && less $FILE)
done
# When script terminates, there is no need to 'cd' back to original directory,
#+ because 'cd $home' takes place in a subshell.
exit 0
COMMAND1
COMMAND2
COMMAND3
(
IFS=:
PATH=/bin
unset TERMINFO
set -C
shift 5
COMMAND4
COMMAND5
exit 3 # Only exits the subshell!
)
# The parent shell has not been affected, and the environment is preserved.
COMMAND6
COMMAND7
if (set -u; : $variable) 2&gt; /dev/null
then
echo "Variable is set."
fi # Variable has been set in current script,
#+ or is an an internal Bash variable,
#+ or is present in environment (has been exported).
# Could also be written [[ ${variable-x} != x || ${variable-y} != y ]]
# or [[ ${variable-x} != x$variable ]]
# or [[ ${variable+x} = x ]]
# or [[ ${variable-x} != x ]]
if (set -C; : &gt; lock_file) 2&gt; /dev/null
then
: # lock_file didn't exist: no user running the script
else
echo "Another user is already running that script."
exit 65
fi
# Code snippet by Stéphane Chazelas,
#+ with modifications by Paulo Marcel Coelho Aragao.
(cat list1 list2 list3 | sort | uniq &gt; list123) &
(cat list4 list5 list6 | sort | uniq &gt; list456) &
# Merges and sorts both sets of lists simultaneously.
# Running in background ensures parallel execution.
#
# Same effect as
# cat list1 list2 list3 | sort | uniq &gt; list123 &
# cat list4 list5 list6 | sort | uniq &gt; list456 &
wait # Don't execute the next command until subshells finish.
diff list123 list456
var1=23
echo "$var1" # 23
{ var1=76; }
echo "$var1" # 76</pre>]
#!/bin/bash
MY_PROMPT='$ '
while :
do
echo -n "$MY_PROMPT"
read line
eval "$line"
done
exit 0
# This example script, and much of the above explanation supplied by
# Stéphane Chazelas (thanks again).
if [ -z $PS1 ] # no prompt?
### if [ -v PS1 ] # On Bash 4.2+ ...
then
# non-interactive
...
else
# interactive
...
fi
case $- in
*i*) # interactive shell
;;
*) # non-interactive shell
;;
# (Courtesy of "UNIX F.A.Q.," 1993)
# Test for a terminal!
fd=0 # stdin
# As we recall, the -t test option checks whether the stdin, [ -t 0 ],
#+ or stdout, [ -t 1 ], in a given script is running in a terminal.
if [ -t "$fd" ]
then
echo interactive
else
echo non-interactive
fi
# But, as John points out:
# if [ -t 0 ] works ... when you're logged in locally
# but fails when you invoke the command remotely via ssh.
# So for a true test you also have to test for a socket.
if [[ -t "$fd" || -p /dev/stdin ]]
then
echo interactive
else
echo non-interactive
fi</pre>]
[]
A. All previous releases of the Advanced Bash Scripting Guide
are as well granted to the Public Domain.
A1. All printed editions, whether authorized by the author or not,
are as well granted to the Public Domain. This legally overrides
any stated intention or wishes of the publishers. Any statement
of copyright is void and invalid.
THERE ARE NO EXCEPTIONS TO THIS.
A2. Any release of the Advanced Bash Scripting Guide, whether in
electronic or print form is granted to the Public Domain by the
express directive of the author and previous copyright holder, Mendel
Cooper. No other person(s) or entities have ever held a valid copyright.
B. As a Public Domain document, unlimited copying and distribution rights
are granted. There can be NO restrictions. If anyone has published or will
in the future publish an original or modified version of this document,
then only additional original material may be copyrighted. The core
work will remain in the Public Domain.
If you copy or distribute this book, kindly DO NOT
use the materials within, or any portion thereof, in a patent or copyright
lawsuit against the Open Source community, its developers, its
distributors, or against any of its associated software or documentation
including, but not limited to, the Linux kernel, Open Office, Samba,
and Wine. Kindly DO NOT use any of the materials within
this book in testimony or depositions as a plaintiff's "expert witness" in
any lawsuit against the Open Source community, any of its developers, its
distributors, or any of its associated software or documentation.</pre>]
#!/bin/bash
# spawn.sh
PIDS=$(pidof sh $0) # Process IDs of the various instances of this script.
P_array=( $PIDS ) # Put them in an array (why?).
echo $PIDS # Show process IDs of parent and child processes.
let "instances = ${#P_array[*]} - 1" # Count elements, less 1.
# Why subtract 1?
echo "$instances instance(s) of this script running."
echo "[Hit Ctl-C to exit.]"; echo
sleep 1 # Wait.
sh $0 # Play it again, Sam.
exit 0 # Not necessary; script will never get to here.
# Why not?
# After exiting with a Ctl-C,
#+ do all the spawned instances of the script die?
# If so, why?
# Note:
# ----
# Be careful not to run this script too long.
# It will eventually eat up too many system resources.
# Is having a script spawn multiple instances of itself
#+ an advisable scripting technique.
# Why or why not?
#!/bin/bash
echo "This line uses the \"echo\" builtin."
/bin/echo "This line uses the /bin/echo system command."
echo Hello
echo $a
if echo "$VAR" | grep -q txt # if [[ $VAR = *txt* ]]
then
echo "$VAR contains the substring sequence \"txt\""
fi
# Embedding a linefeed?
echo "Why doesn't this string \n split on two lines?"
# Doesn't split.
# Let's try something else.
echo
echo $"A line of text containing
a linefeed."
# Prints as two distinct lines (embedded linefeed).
# But, is the "$" variable prefix really necessary?
echo
echo "This string splits
on two lines."
# No, the "$" is not needed.
echo
echo "---------------"
echo
echo -n $"Another line of text containing
a linefeed."
# Prints as two distinct lines (embedded linefeed).
# Even the -n option fails to suppress the linefeed here.
echo
echo
echo "---------------"
echo
echo
# However, the following doesn't work as expected.
# Why not? Hint: Assignment to a variable.
string1=$"Yet another line of text containing
a linefeed (maybe)."
echo $string1
# Yet another line of text containing a linefeed (maybe).
# ^
# Linefeed becomes a space.
# Thanks, Steve Parker, for pointing this out.
#!/bin/bash
# printf demo
declare -r PI=3.14159265358979 # Read-only variable, i.e., a constant.
declare -r DecimalConstant=31373
Message1="Greetings,"
Message2="Earthling."
echo
printf "Pi to 2 decimal places = %1.2f" $PI
echo
printf "Pi to 9 decimal places = %1.9f" $PI # It even rounds off correctly.
printf "\n" # Prints a line feed,
# Equivalent to 'echo' . . .
printf "Constant = \t%d\n" $DecimalConstant # Inserts tab (\t).
printf "%s %s \n" $Message1 $Message2
echo
# ==========================================#
# Simulation of C function, sprintf().
# Loading a variable with a formatted string.
echo
Pi12=$(printf "%1.12f" $PI)
echo "Pi to 12 decimal places = $Pi12" # Roundoff error!
Msg=`printf "%s %s \n" $Message1 $Message2`
echo $Msg; echo $Msg
# As it happens, the 'sprintf' function can now be accessed
#+ as a loadable module to Bash,
#+ but this is not portable.
exit 0
E_BADDIR=85
var=nonexistent_directory
error()
{
printf "$@" &gt;&2
# Formats positional params passed, and sends them to stderr.
echo
exit $E_BADDIR
}
cd $var || error $"Can't cd to %s." "$var"
# Thanks, S.C.
#!/bin/bash
# "Reading" variables.
echo -n "Enter the value of variable 'var1': "
# The -n option to echo suppresses newline.
read var1
# Note no '$' in front of var1, since it is being set.
echo "var1 = $var1"
echo
# A single 'read' statement can set multiple variables.
echo -n "Enter the values of variables 'var2' and 'var3' "
echo =n "(separated by a space or tab): "
read var2 var3
echo "var2 = $var2 var3 = $var3"
# If you input only one value,
#+ the other variable(s) will remain unset (null).
exit 0
#!/bin/bash
# read-novar.sh
echo
# -------------------------- #
echo -n "Enter a value: "
read var
echo "\"var\" = "$var""
# Everything as expected here.
# -------------------------- #
echo
# ------------------------------------------------------------------- #
echo -n "Enter another value: "
read # No variable supplied for 'read', therefore...
#+ Input to 'read' assigned to default variable, $REPLY.
var="$REPLY"
echo "\"var\" = "$var""
# This is equivalent to the first code block.
# ------------------------------------------------------------------- #
echo
echo "========================="
echo
# This example is similar to the "reply.sh" script.
# However, this one shows that $REPLY is available
#+ even after a 'read' to a variable in the conventional way.
# ================================================================= #
# In some instances, you might wish to discard the first value read.
# In such cases, simply ignore the $REPLY variable.
{ # Code block.
read # Line 1, to be discarded.
read line2 # Line 2, saved in variable.
} <$0
echo "Line 2 of this script is:"
echo "$line2" # # read-novar.sh
echo # #!/bin/bash line discarded.
# See also the soundcard-on.sh script.
exit 0
#!/bin/bash
echo
echo "Enter a string terminated by a \\, then press <ENTER&gt;."
echo "Then, enter a second string (no \\ this time), and again press <ENTER&gt;."
read var1 # The "\" suppresses the newline, when reading $var1.
# first line \
# second line
echo "var1 = $var1"
# var1 = first line second line
# For each line terminated by a "\"
#+ you get a prompt on the next line to continue feeding characters into var1.
echo; echo
echo "Enter another string terminated by a \\ , then press <ENTER&gt;."
read -r var2 # The -r option causes the "\" to be read literally.
# first line \
echo "var2 = $var2"
# var2 = first line \
# Data entry terminates with the first <ENTER&gt;.
echo
exit 0
# Read a keypress without hitting ENTER.
read -s -n1 -p "Hit a key " keypress
echo; echo "Keypress was "\"$keypress\""."
# -s option means do not echo input.
# -n N option means accept only N characters of input.
# -p option means echo the following prompt before reading input.
# Using these options is tricky, since they need to be in the correct order.
#!/bin/bash
# arrow-detect.sh: Detects the arrow keys, and a few more.
# Thank you, Sandro Magi, for showing me how.
# --------------------------------------------
# Character codes generated by the keypresses.
arrowup='\[A'
arrowdown='\[B'
arrowrt='\[C'
arrowleft='\[D'
insert='\[2'
delete='\[3'
# --------------------------------------------
SUCCESS=0
OTHER=65
echo -n "Press a key... "
# May need to also press ENTER if a key not listed above pressed.
read -n3 key # Read 3 characters.
echo -n "$key" | grep "$arrowup" #Check if character code detected.
if [ "$?" -eq $SUCCESS ]
then
echo "Up-arrow key pressed."
exit $SUCCESS
fi
echo -n "$key" | grep "$arrowdown"
if [ "$?" -eq $SUCCESS ]
then
echo "Down-arrow key pressed."
exit $SUCCESS
fi
echo -n "$key" | grep "$arrowrt"
if [ "$?" -eq $SUCCESS ]
then
echo "Right-arrow key pressed."
exit $SUCCESS
fi
echo -n "$key" | grep "$arrowleft"
if [ "$?" -eq $SUCCESS ]
then
echo "Left-arrow key pressed."
exit $SUCCESS
fi
echo -n "$key" | grep "$insert"
if [ "$?" -eq $SUCCESS ]
then
echo "\"Insert\" key pressed."
exit $SUCCESS
fi
echo -n "$key" | grep "$delete"
if [ "$?" -eq $SUCCESS ]
then
echo "\"Delete\" key pressed."
exit $SUCCESS
fi
echo " Some other key pressed."
exit $OTHER
# ========================================= #
# Mark Alexander came up with a simplified
#+ version of the above script (Thank you!).
# It eliminates the need for grep.
#!/bin/bash
uparrow=$'\x1b[A'
downarrow=$'\x1b[B'
leftarrow=$'\x1b[D'
rightarrow=$'\x1b[C'
read -s -n3 -p "Hit an arrow key: " x
case "$x" in
$uparrow)
echo "You pressed up-arrow"
;;
$downarrow)
echo "You pressed down-arrow"
;;
$leftarrow)
echo "You pressed left-arrow"
;;
$rightarrow)
echo "You pressed right-arrow"
;;
esac
exit $?
# ========================================= #
# Antonio Macchi has a simpler alternative.
#!/bin/bash
while true
do
read -sn1 a
test "$a" == `echo -en "\e"` || continue
read -sn1 a
test "$a" == "[" || continue
read -sn1 a
case "$a" in
A) echo "up";;
B) echo "down";;
C) echo "right";;
D) echo "left";;
esac
done
# ========================================= #
# Exercise:
# --------
# 1) Add detection of the "Home," "End," "PgUp," and "PgDn" keys.
#!/bin/bash
read var1 <data-file
echo "var1 = $var1"
# var1 set to the entire first line of the input file "data-file"
read var2 var3 <data-file
echo "var2 = $var2 var3 = $var3"
# Note non-intuitive behavior of "read" here.
# 1) Rewinds back to the beginning of input file.
# 2) Each variable is now set to a corresponding string,
# separated by whitespace, rather than to an entire line of text.
# 3) The final variable gets the remainder of the line.
# 4) If there are more variables to be set than whitespace-terminated strings
# on the first line of the file, then the excess variables remain empty.
echo "------------------------------------------------"
# How to resolve the above problem with a loop:
while read line
do
echo "$line"
done <data-file
# Thanks, Heiner Steven for pointing this out.
echo "------------------------------------------------"
# Use $IFS (Internal Field Separator variable) to split a line of input to
# "read", if you do not want the default to be whitespace.
echo "List of all users:"
OIFS=$IFS; IFS=: # /etc/passwd uses ":" for field separator.
while read name passwd uid gid fullname ignore
do
echo "$name ($fullname)"
done </etc/passwd # I/O redirection.
IFS=$OIFS # Restore original $IFS.
# This code snippet also by Heiner Steven.
# Setting the $IFS variable within the loop itself
#+ eliminates the need for storing the original $IFS
#+ in a temporary variable.
# Thanks, Dim Segebart, for pointing this out.
echo "------------------------------------------------"
echo "List of all users:"
while IFS=: read name passwd uid gid fullname ignore
do
echo "$name ($fullname)"
done </etc/passwd # I/O redirection.
echo
echo "\$IFS still $IFS"
exit 0
cat file1 file2 |
while read line
do
echo $line
done
#!/bin/sh
# readpipe.sh
# This example contributed by Bjon Eriksson.
### shopt -s lastpipe
last="(null)"
cat $0 |
while read line
do
echo "{$line}"
last=$line
done
echo
echo "++++++++++++++++++++++"
printf "\nAll done, last: $last\n" # The output of this line
#+ changes if you uncomment line 5.
# (Bash, version -ge 4.2 required.)
exit 0 # End of code.
# (Partial) output of script follows.
# The 'echo' supplies extra brackets.
#############################################
./readpipe.sh
{#!/bin/sh}
{last="(null)"}
{cat $0 |}
{while read line}
{do}
{echo "{$line}"}
{last=$line}
{done}
{printf "nAll done, last: $lastn"}
All done, last: (null)
The variable (last) is set within the loop/subshell
but its value does not persist outside the loop.
find $1 \( -name "*$2" -o -name ".*$2" \) -print |
while read f; do
. . .
(cd /source/directory && tar cf - . ) | (cd /dest/directory && tar xpvf -)
#!/bin/bash
dir1=/usr/local
dir2=/var/spool
pushd $dir1
# Will do an automatic 'dirs' (list directory stack to stdout).
echo "Now in directory `pwd`." # Uses back-quoted 'pwd'.
# Now, do some stuff in directory 'dir1'.
pushd $dir2
echo "Now in directory `pwd`."
# Now, do some stuff in directory 'dir2'.
echo "The top entry in the DIRSTACK array is $DIRSTACK."
popd
echo "Now back in directory `pwd`."
# Now, do some more stuff in directory 'dir1'.
popd
echo "Now back in original working directory `pwd`."
exit 0
# What happens if you don't 'popd' -- then exit the script?
# Which directory do you end up in? Why?
#!/bin/bash
echo
let a=11 # Same as 'a=11'
let a=a+5 # Equivalent to let "a = a + 5"
# (Double quotes and spaces make it more readable.)
echo "11 + 5 = $a" # 16
let "a <<= 3" # Equivalent to let "a = a << 3"
echo "\"\$a\" (=16) left-shifted 3 places = $a"
# 128
let "a /= 4" # Equivalent to let "a = a / 4"
echo "128 / 4 = $a" # 32
let "a -= 5" # Equivalent to let "a = a - 5"
echo "32 - 5 = $a" # 27
let "a *= 10" # Equivalent to let "a = a * 10"
echo "27 * 10 = $a" # 270
let "a %= 8" # Equivalent to let "a = a % 8"
echo "270 modulo 8 = $a (270 / 8 = 33, remainder $a)"
# 6
# Does "let" permit C-style operators?
# Yes, just as the (( ... )) double-parentheses construct does.
let a++ # C-style (post) increment.
echo "6++ = $a" # 6++ = 7
let a-- # C-style decrement.
echo "7-- = $a" # 7-- = 6
# Of course, ++a, etc., also allowed . . .
echo
# Trinary operator.
# Note that $a is 6, see above.
let "t = a<7?7:11" # True
echo $t # 7
let a++
let "t = a<7?7:11" # False
echo $t # 11
exit
# Evgeniy Ivanov points out:
var=0
echo $? # 0
# As expected.
let var++
echo $? # 1
# The command was successful, so why isn't $?=0 ???
# Anomaly!
let var++
echo $? # 0
# As expected.
# Likewise . . .
let var=0
echo $? # 1
# The command was successful, so why isn't $?=0 ???
# However, as Jeff Gorak points out,
#+ this is part of the design spec for 'let' . . .
# "If the last ARG evaluates to 0, let returns 1;
# let returns 0 otherwise." ['help let']
a='$b'
b='$c'
c=d
echo $a # $b
# First level.
eval echo $a # $c
# Second level.
eval eval echo $a # d
# Third level.
# Thank you, E. Choroba.
#!/bin/bash
# Exercising "eval" ...
y=`eval ls -l` # Similar to y=`ls -l`
echo $y #+ but linefeeds removed because "echoed" variable is unquoted.
echo
echo "$y" # Linefeeds preserved when variable is quoted.
echo; echo
y=`eval df` # Similar to y=`df`
echo $y #+ but linefeeds removed.
# When LF's not preserved, it may make it easier to parse output,
#+ using utilities such as "awk".
echo
echo "==========================================================="
echo
eval "`seq 3 | sed -e 's/.*/echo var&=ABCDEFGHIJ/'`"
# var1=ABCDEFGHIJ
# var2=ABCDEFGHIJ
# var3=ABCDEFGHIJ
echo
echo "==========================================================="
echo
# Now, showing how to do something useful with "eval" . . .
# (Thank you, E. Choroba!)
version=3.4 # Can we split the version into major and minor
#+ part in one command?
echo "version = $version"
eval major=${version/./;minor=} # Replaces '.' in version by ';minor='
# The substitution yields '3; minor=4'
#+ so eval does minor=4, major=3
echo Major: $major, minor: $minor # Major: 3, minor: 4
#!/bin/bash
# arr-choice.sh
# Passing arguments to a function to select
#+ one particular variable out of a group.
arr0=( 10 11 12 13 14 15 )
arr1=( 20 21 22 23 24 25 )
arr2=( 30 31 32 33 34 35 )
# 0 1 2 3 4 5 Element number (zero-indexed)
choose_array ()
{
eval array_member=\${arr${array_number}[element_number]}
# ^ ^^^^^^^^^^^^
# Using eval to construct the name of a variable,
#+ in this particular case, an array name.
echo "Element $element_number of array $array_number is $array_member"
} # Function can be rewritten to take parameters.
array_number=0 # First array.
element_number=3
choose_array # 13
array_number=2 # Third array.
element_number=4
choose_array # 34
array_number=3 # Null array (arr3 not allocated).
element_number=4
choose_array # (null)
# Thank you, Antonio Macchi, for pointing this out.
#!/bin/bash
# echo-params.sh
# Call this script with a few command-line parameters.
# For example:
# sh echo-params.sh first second third fourth fifth
params=$# # Number of command-line parameters.
param=1 # Start at first command-line param.
while [ "$param" -le "$params" ]
do
echo -n "Command-line parameter "
echo -n \$$param # Gives only the *name* of variable.
# ^^^ # $1, $2, $3, etc.
# Why?
# \$ escapes the first "$"
#+ so it echoes literally,
#+ and $param dereferences "$param" . . .
#+ . . . as expected.
echo -n " = "
eval echo \$$param # Gives the *value* of variable.
# ^^^^ ^^^ # The "eval" forces the *evaluation*
#+ of \$$
#+ as an indirect variable reference.
(( param ++ )) # On to the next.
done
exit $?
# =================================================
$ sh echo-params.sh first second third fourth fifth
Command-line parameter $1 = first
Command-line parameter $2 = second
Command-line parameter $3 = third
Command-line parameter $4 = fourth
Command-line parameter $5 = fifth
#!/bin/bash
# Killing ppp to force a log-off.
# For dialup connection, of course.
# Script should be run as root user.
SERPORT=ttyS3
# Depending on the hardware and even the kernel version,
#+ the modem port on your machine may be different --
#+ /dev/ttyS1 or /dev/ttyS2.
killppp="eval kill -9 `ps ax | awk '/ppp/ { print $1 }'`"
# -------- process ID of ppp -------
$killppp # This variable is now a command.
# The following operations must be done as root user.
chmod 666 /dev/$SERPORT # Restore r+w permissions, or else what?
# Since doing a SIGKILL on ppp changed the permissions on the serial port,
#+ we restore permissions to previous state.
rm /var/lock/LCK..$SERPORT # Remove the serial port lock file. Why?
exit $?
# Exercises:
# ---------
# 1) Have script check whether root user is invoking it.
# 2) Do a check on whether the process to be killed
#+ is actually running before attempting to kill it.
# 3) Write an alternate version of this script based on 'fuser':
#+ if [ fuser -s /dev/modem ]; then . . .
#!/bin/bash
# A version of "rot13" using 'eval'.
# Compare to "rot13.sh" example.
setvar_rot_13() # "rot13" scrambling
{
local varname=$1 varvalue=$2
eval $varname='$(echo "$varvalue" | tr a-z n-za-m)'
}
setvar_rot_13 var "foobar" # Run "foobar" through rot13.
echo $var # sbbone
setvar_rot_13 var "$var" # Run "sbbone" through rot13.
# Back to original variable.
echo $var # foobar
# This example by Stephane Chazelas.
# Modified by document author.
exit 0
eval ${1}+=\"${x} ${y} \"
eval var=\$$var
#!/bin/bash
# ex34.sh
# Script "set-test"
# Invoke this script with three command-line parameters,
# for example, "sh ex34.sh one two three".
echo
echo "Positional parameters before set \`uname -a\` :"
echo "Command-line argument #1 = $1"
echo "Command-line argument #2 = $2"
echo "Command-line argument #3 = $3"
set `uname -a` # Sets the positional parameters to the output
# of the command `uname -a`
echo
echo +++++
echo $_ # +++++
# Flags set in script.
echo $- # hB
# Anomalous behavior?
echo
echo "Positional parameters after set \`uname -a\` :"
# $1, $2, $3, etc. reinitialized to result of `uname -a`
echo "Field #1 of 'uname -a' = $1"
echo "Field #2 of 'uname -a' = $2"
echo "Field #3 of 'uname -a' = $3"
echo \#\#\#
echo $_ # ###
echo
exit 0
#!/bin/bash
# revposparams.sh: Reverse positional parameters.
# Script by Dan Jacobson, with stylistic revisions by document author.
set a\ b c d\ e;
# ^ ^ Spaces escaped
# ^ ^ Spaces not escaped
OIFS=$IFS; IFS=:;
# ^ Saving old IFS and setting new one.
echo
until [ $# -eq 0 ]
do # Step through positional parameters.
echo "### k0 = "$k"" # Before
k=$1:$k; # Append each pos param to loop variable.
# ^
echo "### k = "$k"" # After
echo
shift;
done
set $k # Set new positional parameters.
echo -
echo $# # Count of positional parameters.
echo -
echo
for i # Omitting the "in list" sets the variable -- i --
#+ to the positional parameters.
do
echo $i # Display new positional parameters.
done
IFS=$OIFS # Restore IFS.
# Question:
# Is it necessary to set an new IFS, internal field separator,
#+ in order for this script to work properly?
# What happens if you don't? Try it.
# And, why use the new IFS -- a colon -- in line 17,
#+ to append to the loop variable?
# What is the purpose of this?
exit 0
$ ./revposparams.sh
### k0 =
### k = a b
### k0 = a b
### k = c a b
### k0 = c a b
### k = d e c a b
-
3
-
d e
c
a b
#!/bin/bash
variable="one two three four five"
set -- $variable
# Sets positional parameters to the contents of "$variable".
first_param=$1
second_param=$2
shift; shift # Shift past first two positional params.
# shift 2 also works.
remaining_params="$*"
echo
echo "first parameter = $first_param" # one
echo "second parameter = $second_param" # two
echo "remaining parameters = $remaining_params" # three four five
echo; echo
# Again.
set -- $variable
first_param=$1
second_param=$2
echo "first parameter = $first_param" # one
echo "second parameter = $second_param" # two
# ======================================================
set --
# Unsets positional parameters if no variable specified.
first_param=$1
second_param=$2
echo "first parameter = $first_param" # (null value)
echo "second parameter = $second_param" # (null value)
exit 0
#!/bin/bash
# unset.sh: Unsetting a variable.
variable=hello # Initialized.
echo "variable = $variable"
unset variable # Unset.
# In this particular context,
#+ same effect as: variable=
echo "(unset) variable = $variable" # $variable is null.
if [ -z "$variable" ] # Try a string-length test.
then
echo "\$variable has zero length."
fi
exit 0
#!/bin/bash
# Yet another version of the "column totaler" script (col-totaler.sh)
#+ that adds up a specified column (of numbers) in the target file.
# This uses the environment to pass a script variable to 'awk' . . .
#+ and places the awk script in a variable.
ARGS=2
E_WRONGARGS=85
if [ $# -ne "$ARGS" ] # Check for proper number of command-line args.
then
echo "Usage: `basename $0` filename column-number"
exit $E_WRONGARGS
fi
filename=$1
column_number=$2
#===== Same as original script, up to this point =====#
export column_number
# Export column number to environment, so it's available for retrieval.
# -----------------------------------------------
awkscript='{ total += $ENVIRON["column_number"] }
END { print total }'
# Yes, a variable can hold an awk script.
# -----------------------------------------------
# Now, run the awk script.
awk "$awkscript" "$filename"
# Thanks, Stephane Chazelas.
exit 0
while getopts ":abcde:fg" Option
# Initial declaration.
# a, b, c, d, e, f, and g are the options (flags) expected.
# The : after option 'e' shows it will have an argument passed with it.
do
case $Option in
a ) # Do something with variable 'a'.
b ) # Do something with variable 'b'.
...
e) # Do something with 'e', and also with $OPTARG,
# which is the associated argument passed with option 'e'.
...
g ) # Do something with variable 'g'.
esac
done
shift $(($OPTIND - 1))
# Move argument pointer to next.
# All this is not nearly as complicated as it looks <grin&gt;.
#!/bin/bash
# ex33.sh: Exercising getopts and OPTIND
# Script modified 10/09/03 at the suggestion of Bill Gradwohl.
# Here we observe how 'getopts' processes command-line arguments to script.
# The arguments are parsed as "options" (flags) and associated arguments.
# Try invoking this script with:
# 'scriptname -mn'
# 'scriptname -oq qOption' (qOption can be some arbitrary string.)
# 'scriptname -qXXX -r'
#
# 'scriptname -qr'
#+ - Unexpected result, takes "r" as the argument to option "q"
# 'scriptname -q -r'
#+ - Unexpected result, same as above
# 'scriptname -mnop -mnop' - Unexpected result
# (OPTIND is unreliable at stating where an option came from.)
#
# If an option expects an argument ("flag:"), then it will grab
#+ whatever is next on the command-line.
NO_ARGS=0
E_OPTERROR=85
if [ $# -eq "$NO_ARGS" ] # Script invoked with no command-line args?
then
echo "Usage: `basename $0` options (-mnopqrs)"
exit $E_OPTERROR # Exit and explain usage.
# Usage: scriptname -options
# Note: dash (-) necessary
fi
while getopts ":mnopq:rs" Option
do
case $Option in
m ) echo "Scenario #1: option -m- [OPTIND=${OPTIND}]";;
n | o ) echo "Scenario #2: option -$Option- [OPTIND=${OPTIND}]";;
p ) echo "Scenario #3: option -p- [OPTIND=${OPTIND}]";;
q ) echo "Scenario #4: option -q-\
with argument \"$OPTARG\" [OPTIND=${OPTIND}]";;
# Note that option 'q' must have an associated argument,
#+ otherwise it falls through to the default.
r | s ) echo "Scenario #5: option -$Option-";;
* ) echo "Unimplemented option chosen.";; # Default.
esac
done
shift $(($OPTIND - 1))
# Decrements the argument pointer so it points to next argument.
# $1 now references the first non-option item supplied on the command-line
#+ if one exists.
exit $?
# As Bill Gradwohl states,
# "The getopts mechanism allows one to specify: scriptname -mnop -mnop
#+ but there is no reliable way to differentiate what came
#+ from where by using OPTIND."
# There are, however, workarounds.
#!/bin/bash
# Note that this example must be invoked with bash, i.e., bash ex38.sh
#+ not sh ex38.sh !
. data-file # Load a data file.
# Same effect as "source data-file", but more portable.
# The file "data-file" must be present in current working directory,
#+ since it is referred to by its basename.
# Now, let's reference some data from that file.
echo "variable1 (from data-file) = $variable1"
echo "variable3 (from data-file) = $variable3"
let "sum = $variable2 + $variable4"
echo "Sum of variable2 + variable4 (from data-file) = $sum"
echo "message1 (from data-file) is \"$message1\""
# Escaped quotes
echo "message2 (from data-file) is \"$message2\""
print_message This is the message-print function in the data-file.
exit $?
# This is a data file loaded by a script.
# Files of this type may contain variables, functions, etc.
# It loads with a 'source' or '.' command from a shell script.
# Let's initialize some variables.
variable1=23
variable2=474
variable3=5
variable4=97
message1="Greetings from *** line $LINENO *** of the data file!"
message2="Enough for now. Goodbye."
print_message ()
{ # Echoes any message passed to it.
if [ -z "$1" ]
then
return 1 # Error, if argument missing.
fi
echo
until [ -z "$1" ]
do # Step through arguments passed to function.
echo -n "$1" # Echo args one at a time, suppressing line feeds.
echo -n " " # Insert spaces between words.
shift # Next one.
done
echo
return 0
}
source $filename $arg1 arg2
#!/bin/bash
# self-source.sh: a script sourcing itself "recursively."
# From "Stupid Script Tricks," Volume II.
MAXPASSCNT=100 # Maximum number of execution passes.
echo -n "$pass_count "
# At first execution pass, this just echoes two blank spaces,
#+ since $pass_count still uninitialized.
let "pass_count += 1"
# Assumes the uninitialized variable $pass_count
#+ can be incremented the first time around.
# This works with Bash and pdksh, but
#+ it relies on non-portable (and possibly dangerous) behavior.
# Better would be to initialize $pass_count to 0 before incrementing.
while [ "$pass_count" -le $MAXPASSCNT ]
do
. $0 # Script "sources" itself, rather than calling itself.
# ./$0 (which would be true recursion) doesn't work here. Why?
done
# What occurs here is not actually recursion,
#+ since the script effectively "expands" itself, i.e.,
#+ generates a new section of code
#+ with each pass through the 'while' loop',
# with each 'source' in line 20.
#
# Of course, the script interprets each newly 'sourced' "#!" line
#+ as a comment, and not as the start of a new script.
echo
exit 0 # The net effect is counting from 1 to 100.
# Very impressive.
# Exercise:
# --------
# Write a script that uses this trick to actually do something useful.
#!/bin/bash
exec echo "Exiting \"$0\" at line $LINENO." # Exit from script here.
# $LINENO is an internal Bash variable set to the line number it's on.
# ----------------------------------
# The following lines never execute.
echo "This echo fails to echo."
exit 99 # This script will not exit here.
# Check exit value after script terminates
#+ with an 'echo $?'.
# It will *not* be 99.
#!/bin/bash
# self-exec.sh
# Note: Set permissions on this script to 555 or 755,
# then call it with ./self-exec.sh or sh ./self-exec.sh.
echo
echo "This line appears ONCE in the script, yet it keeps echoing."
echo "The PID of this instance of the script is still $$."
# Demonstrates that a subshell is not forked off.
echo "==================== Hit Ctl-C to exit ===================="
sleep 1
exec $0 # Spawns another instance of this same script
#+ that replaces the previous one.
echo "This line will never echo!" # Why not?
exit 99 # Will not exit here!
# Exit code will not be 99!
shopt -s cdspell
# Allows minor misspelling of directory names with 'cd'
# Option -s sets, -u unsets.
cd /hpme # Oops! Mistyped '/home'.
pwd # /home
# The shell corrected the misspelling.
#!/bin/bash
function1 ()
{
# Inside function1 ().
caller 0 # Tell me about it.
}
function1 # Line 9 of script.
# 9 main test.sh
# ^ Line number that the function was called from.
# ^^^^ Invoked from "main" part of script.
# ^^^^^^^ Name of calling script.
caller 0 # Has no effect because it's not inside a function.
# Endless loop
while true # alias for ":"
do
operation-1
operation-2
...
operation-n
# Need a way to break out of loop or script will hang.
done
# Testing "false"
if false
then
echo "false evaluates \"true\""
else
echo "false evaluates \"false\""
fi
# false evaluates "false"
# Looping while "false" (null loop)
while false
do
# The following code will not execute.
operation-1
operation-2
...
operation-n
# Nothing happens!
done </pre>]
#!/bin/bash
COMMAND_1
. . .
COMMAND_LAST
# Will exit with status of last command.
exit
#!/bin/bash
COMMAND_1
. . .
COMMAND_LAST
# Will exit with status of last command.
exit $?
#!/bin/bash
COMMAND1
. . .
COMMAND_LAST
# Will exit with status of last command.
#!/bin/bash
echo hello
echo $? # Exit status 0 returned because command executed successfully.
lskdf # Unrecognized command.
echo $? # Non-zero exit status returned -- command failed to execute.
echo
exit 113 # Will return 113 to shell.
# To verify this, type "echo $?" after script terminates.
# By convention, an 'exit 0' indicates success,
#+ while a non-zero exit value means an error or anomalous condition.
# See the "Exit Codes With Special Meanings" appendix.
true # The "true" builtin.
echo "exit status of \"true\" = $?" # 0
! true
echo "exit status of \"! true\" = $?" # 1
# Note that the "!" needs a space between it and the command.
# !true leads to a "command not found" error
#
# The '!' operator prefixing a command invokes the Bash history mechanism.
true
!true
# No error this time, but no negation either.
# It just repeats the previous command (true).
# =========================================================== #
# Preceding a _pipe_ with ! inverts the exit status returned.
ls | bogus_command # bash: bogus_command: command not found
echo $? # 127
! ls | bogus_command # bash: bogus_command: command not found
echo $? # 0
# Note that the ! does not change the execution of the pipe.
# Only the exit status changes.
# =========================================================== #
# Thanks, Stéphane Chazelas and Kristopher Newsome.</pre>]
# Instead of:
if echo "$VAR" | grep -q txt # if [[ $VAR = *txt* ]]
# etc.
# Try:
if grep -q "txt" <<< "$VAR"
then # ^^^
echo "$VAR contains the substring sequence \"txt\""
fi
# Thank you, Sebastian Kaminski, for the suggestion.
String="This is a string of words."
read -r -a Words <<< "$String"
# The -a option to "read"
#+ assigns the resulting values to successive members of an array.
echo "First word in String is: ${Words[0]}" # This
echo "Second word in String is: ${Words[1]}" # is
echo "Third word in String is: ${Words[2]}" # a
echo "Fourth word in String is: ${Words[3]}" # string
echo "Fifth word in String is: ${Words[4]}" # of
echo "Sixth word in String is: ${Words[5]}" # words.
echo "Seventh word in String is: ${Words[6]}" # (null)
# Past end of $String.
# Thank you, Francisco Lobo, for the suggestion.
# As Seamus points out . . .
ArrayVar=( element0 element1 element2 {A..D} )
while read element ; do
echo "$element" 1&gt;&2
done <<< $(echo ${ArrayVar[*]})
# element0 element1 element2 A B C D
#!/bin/bash
# prepend.sh: Add text at beginning of file.
#
# Example contributed by Kenny Stauffer,
#+ and slightly modified by document author.
E_NOSUCHFILE=85
read -p "File: " file # -p arg to 'read' displays prompt.
if [ ! -e "$file" ]
then # Bail out if no such file.
echo "File $file not found."
exit $E_NOSUCHFILE
fi
read -p "Title: " title
cat - $file <<<$title &gt; $file.new
echo "Modified file is $file.new"
exit # Ends script execution.
from 'man bash':
Here Strings
A variant of here documents, the format is:
<<<word
The word is expanded and supplied to the command on its standard input.
Of course, the following also works:
sed -e '1i\
Title: ' $file
#!/bin/bash
# Script by Francisco Lobo,
#+ and slightly modified and commented by ABS Guide author.
# Used in ABS Guide with permission. (Thank you!)
# This script will not run under Bash versions -lt 3.0.
E_MISSING_ARG=87
if [ -z "$1" ]
then
echo "Usage: $0 mailbox-file"
exit $E_MISSING_ARG
fi
mbox_grep() # Parse mailbox file.
{
declare -i body=0 match=0
declare -a date sender
declare mail header value
while IFS= read -r mail
# ^^^^ Reset $IFS.
# Otherwise "read" will strip leading & trailing space from its input.
do
if [[ $mail =~ ^From ]] # Match "From" field in message.
then
(( body = 0 )) # "Zero out" variables.
(( match = 0 ))
unset date
elif (( body ))
then
(( match ))
# echo "$mail"
# Uncomment above line if you want entire body
#+ of message to display.
elif [[ $mail ]]; then
IFS=: read -r header value <<< "$mail"
# ^^^ "here string"
case "$header" in
[Ff][Rr][Oo][Mm] ) [[ $value =~ "$2" ]] && (( match++ )) ;;
# Match "From" line.
[Dd][Aa][Tt][Ee] ) read -r -a date <<< "$value" ;;
# ^^^
# Match "Date" line.
[Rr][Ee][Cc][Ee][Ii][Vv][Ee][Dd] ) read -r -a sender <<< "$value" ;;
# ^^^
# Match IP Address (may be spoofed).
esac
else
(( body++ ))
(( match )) &&
echo "MESSAGE ${date:+of: ${date[*]} }"
# Entire $date array ^
echo "IP address of sender: ${sender[1]}"
# Second field of "Received" line ^
fi
done < "$1" # Redirect stdout of file into loop.
}
mbox_grep "$1" # Send mailbox file to function.
exit $?
# Exercises:
# ---------
# 1) Break the single function, above, into multiple functions,
#+ for the sake of readability.
# 2) Add additional parsing to the script, checking for various keywords.
$ mailbox_grep.sh scam_mail
MESSAGE of Thu, 5 Jan 2006 08:00:56 -0500 (EST)
IP address of sender: 196.3.62.4</pre>]
# =============================================================== #
#
# PERSONAL $HOME/.bashrc FILE for bash-3.0 (or later)
# By Emmanuel Rouat [no-email]
#
# Last modified: Tue Nov 20 22:04:47 CET 2012
# This file is normally read by interactive shells only.
#+ Here is the place to define your aliases, functions and
#+ other interactive features like your prompt.
#
# The majority of the code here assumes you are on a GNU
#+ system (most likely a Linux box) and is often based on code
#+ found on Usenet or Internet.
#
# See for instance:
# http://tldp.org/LDP/abs/html/index.html
# http://www.caliban.org/bash
# http://www.shelldorado.com/scripts/categories.html
# http://www.dotfiles.org
#
# The choice of colors was done for a shell with a dark background
#+ (white on black), and this is usually also suited for pure text-mode
#+ consoles (no X server available). If you use a white background,
#+ you'll have to do some other choices for readability.
#
# This bashrc file is a bit overcrowded.
# Remember, it is just just an example.
# Tailor it to your needs.
#
# =============================================================== #
# --&gt; Comments added by HOWTO author.
# If not running interactively, don't do anything
[ -z "$PS1" ] && return
#-------------------------------------------------------------
# Source global definitions (if any)
#-------------------------------------------------------------
if [ -f /etc/bashrc ]; then
. /etc/bashrc # --&gt; Read /etc/bashrc, if present.
fi
#--------------------------------------------------------------
# Automatic setting of $DISPLAY (if not set already).
# This works for me - your mileage may vary. . . .
# The problem is that different types of terminals give
#+ different answers to 'who am i' (rxvt in particular can be
#+ troublesome) - however this code seems to work in a majority
#+ of cases.
#--------------------------------------------------------------
function get_xserver ()
{
case $TERM in
xterm )
XSERVER=$(who am i | awk '{print $NF}' | tr -d ')''(' )
# Ane-Pieter Wieringa suggests the following alternative:
# I_AM=$(who am i)
# SERVER=${I_AM#*(}
# SERVER=${SERVER%*)}
XSERVER=${XSERVER%%:*}
;;
aterm | rxvt)
# Find some code that works here. ...
;;
esac
}
if [ -z ${DISPLAY:=""} ]; then
get_xserver
if [[ -z ${XSERVER} || ${XSERVER} == $(hostname) ||
${XSERVER} == "unix" ]]; then
DISPLAY=":0.0" # Display on local host.
else
DISPLAY=${XSERVER}:0.0 # Display on remote host.
fi
fi
export DISPLAY
#-------------------------------------------------------------
# Some settings
#-------------------------------------------------------------
#set -o nounset # These two options are useful for debugging.
#set -o xtrace
alias debug="set -o nounset; set -o xtrace"
ulimit -S -c 0 # Don't want coredumps.
set -o notify
set -o noclobber
set -o ignoreeof
# Enable options:
shopt -s cdspell
shopt -s cdable_vars
shopt -s checkhash
shopt -s checkwinsize
shopt -s sourcepath
shopt -s no_empty_cmd_completion
shopt -s cmdhist
shopt -s histappend histreedit histverify
shopt -s extglob # Necessary for programmable completion.
# Disable options:
shopt -u mailwarn
unset MAILCHECK # Don't want my shell to warn me of incoming mail.
#-------------------------------------------------------------
# Greeting, motd etc. ...
#-------------------------------------------------------------
# Color definitions (taken from Color Bash Prompt HowTo).
# Some colors might look different of some terminals.
# For example, I see 'Bold Red' as 'orange' on my screen,
# hence the 'Green' 'BRed' 'Red' sequence I often use in my prompt.
# Normal Colors
Black='\e[0;30m' # Black
Red='\e[0;31m' # Red
Green='\e[0;32m' # Green
Yellow='\e[0;33m' # Yellow
Blue='\e[0;34m' # Blue
Purple='\e[0;35m' # Purple
Cyan='\e[0;36m' # Cyan
White='\e[0;37m' # White
# Bold
BBlack='\e[1;30m' # Black
BRed='\e[1;31m' # Red
BGreen='\e[1;32m' # Green
BYellow='\e[1;33m' # Yellow
BBlue='\e[1;34m' # Blue
BPurple='\e[1;35m' # Purple
BCyan='\e[1;36m' # Cyan
BWhite='\e[1;37m' # White
# Background
On_Black='\e[40m' # Black
On_Red='\e[41m' # Red
On_Green='\e[42m' # Green
On_Yellow='\e[43m' # Yellow
On_Blue='\e[44m' # Blue
On_Purple='\e[45m' # Purple
On_Cyan='\e[46m' # Cyan
On_White='\e[47m' # White
NC="\e[m" # Color Reset
ALERT=${BWhite}${On_Red} # Bold White on red background
echo -e "${BCyan}This is BASH ${BRed}${BASH_VERSION%.*}${BCyan}\
- DISPLAY on ${BRed}$DISPLAY${NC}\n"
date
if [ -x /usr/games/fortune ]; then
/usr/games/fortune -s # Makes our day a bit more fun.... :-)
fi
function _exit() # Function to run upon exit of shell.
{
echo -e "${BRed}Hasta la vista, baby${NC}"
}
trap _exit EXIT
#-------------------------------------------------------------
# Shell Prompt - for many examples, see:
# http://www.debian-administration.org/articles/205
# http://www.askapache.com/linux/bash-power-prompt.html
# http://tldp.org/HOWTO/Bash-Prompt-HOWTO
# https://github.com/nojhan/liquidprompt
#-------------------------------------------------------------
# Current Format: [TIME USER@HOST PWD] &gt;
# TIME:
# Green == machine load is low
# Orange == machine load is medium
# Red == machine load is high
# ALERT == machine load is very high
# USER:
# Cyan == normal user
# Orange == SU to user
# Red == root
# HOST:
# Cyan == local session
# Green == secured remote connection (via ssh)
# Red == unsecured remote connection
# PWD:
# Green == more than 10% free disk space
# Orange == less than 10% free disk space
# ALERT == less than 5% free disk space
# Red == current user does not have write privileges
# Cyan == current filesystem is size zero (like /proc)
# &gt;:
# White == no background or suspended jobs in this shell
# Cyan == at least one background job in this shell
# Orange == at least one suspended job in this shell
#
# Command is added to the history file each time you hit enter,
# so it's available to all shells (using 'history -a').
# Test connection type:
if [ -n "${SSH_CONNECTION}" ]; then
CNX=${Green} # Connected on remote machine, via ssh (good).
elif [[ "${DISPLAY%%:0*}" != "" ]]; then
CNX=${ALERT} # Connected on remote machine, not via ssh (bad).
else
CNX=${BCyan} # Connected on local machine.
fi
# Test user type:
if [[ ${USER} == "root" ]]; then
SU=${Red} # User is root.
elif [[ ${USER} != $(logname) ]]; then
SU=${BRed} # User is not login user.
else
SU=${BCyan} # User is normal (well ... most of us are).
fi
NCPU=$(grep -c 'processor' /proc/cpuinfo) # Number of CPUs
SLOAD=$(( 100*${NCPU} )) # Small load
MLOAD=$(( 200*${NCPU} )) # Medium load
XLOAD=$(( 400*${NCPU} )) # Xlarge load
# Returns system load as percentage, i.e., '40' rather than '0.40)'.
function load()
{
local SYSLOAD=$(cut -d " " -f1 /proc/loadavg | tr -d '.')
# System load of the current host.
echo $((10#$SYSLOAD)) # Convert to decimal.
}
# Returns a color indicating system load.
function load_color()
{
local SYSLOAD=$(load)
if [ ${SYSLOAD} -gt ${XLOAD} ]; then
echo -en ${ALERT}
elif [ ${SYSLOAD} -gt ${MLOAD} ]; then
echo -en ${Red}
elif [ ${SYSLOAD} -gt ${SLOAD} ]; then
echo -en ${BRed}
else
echo -en ${Green}
fi
}
# Returns a color according to free disk space in $PWD.
function disk_color()
{
if [ ! -w "${PWD}" ] ; then
echo -en ${Red}
# No 'write' privilege in the current directory.
elif [ -s "${PWD}" ] ; then
local used=$(command df -P "$PWD" |
awk 'END {print $5} {sub(/%/,"")}')
if [ ${used} -gt 95 ]; then
echo -en ${ALERT} # Disk almost full (&gt;95%).
elif [ ${used} -gt 90 ]; then
echo -en ${BRed} # Free disk space almost gone.
else
echo -en ${Green} # Free disk space is ok.
fi
else
echo -en ${Cyan}
# Current directory is size '0' (like /proc, /sys etc).
fi
}
# Returns a color according to running/suspended jobs.
function job_color()
{
if [ $(jobs -s | wc -l) -gt "0" ]; then
echo -en ${BRed}
elif [ $(jobs -r | wc -l) -gt "0" ] ; then
echo -en ${BCyan}
fi
}
# Adds some text in the terminal frame (if applicable).
# Now we construct the prompt.
PROMPT_COMMAND="history -a"
case ${TERM} in
*term | rxvt | linux)
PS1="\[\$(load_color)\][\A\[${NC}\] "
# Time of day (with load info):
PS1="\[\$(load_color)\][\A\[${NC}\] "
# User@Host (with connection type info):
PS1=${PS1}"\[${SU}\]\u\[${NC}\]@\[${CNX}\]\h\[${NC}\] "
# PWD (with 'disk space' info):
PS1=${PS1}"\[\$(disk_color)\]\W]\[${NC}\] "
# Prompt (with 'job' info):
PS1=${PS1}"\[\$(job_color)\]&gt;\[${NC}\] "
# Set title of current xterm:
PS1=${PS1}"\[\e]0;[\u@\h] \w\a\]"
;;
*)
PS1="(\A \u@\h \W) &gt; " # --&gt; PS1="(\A \u@\h \w) &gt; "
# --&gt; Shows full pathname of current dir.
;;
esac
export TIMEFORMAT=$'\nreal %3R\tuser %3U\tsys %3S\tpcpu %P\n'
export HISTIGNORE="&:bg:fg:ll:h"
export HISTTIMEFORMAT="$(echo -e ${BCyan})[%d/%m %H:%M:%S]$(echo -e ${NC}) "
export HISTCONTROL=ignoredups
export HOSTFILE=$HOME/.hosts # Put a list of remote hosts in ~/.hosts
#============================================================
#
# ALIASES AND FUNCTIONS
#
# Arguably, some functions defined here are quite big.
# If you want to make this file smaller, these functions can
#+ be converted into scripts and removed from here.
#
#============================================================
#-------------------
# Personnal Aliases
#-------------------
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
# -&gt; Prevents accidentally clobbering files.
alias mkdir='mkdir -p'
alias h='history'
alias j='jobs -l'
alias which='type -a'
alias ..='cd ..'
# Pretty-print of some PATH variables:
alias path='echo -e ${PATH//:/\\n}'
alias libpath='echo -e ${LD_LIBRARY_PATH//:/\\n}'
alias du='du -kh' # Makes a more readable output.
alias df='df -kTh'
#-------------------------------------------------------------
# The 'ls' family (this assumes you use a recent GNU ls).
#-------------------------------------------------------------
# Add colors for filetype and human-readable sizes by default on 'ls':
alias ls='ls -h --color'
alias lx='ls -lXB' # Sort by extension.
alias lk='ls -lSr' # Sort by size, biggest last.
alias lt='ls -ltr' # Sort by date, most recent last.
alias lc='ls -ltcr' # Sort by/show change time,most recent last.
alias lu='ls -ltur' # Sort by/show access time,most recent last.
# The ubiquitous 'll': directories first, with alphanumeric sorting:
alias ll="ls -lv --group-directories-first"
alias lm='ll |more' # Pipe through 'more'
alias lr='ll -R' # Recursive ls.
alias la='ll -A' # Show hidden files.
alias tree='tree -Csuh' # Nice alternative to 'recursive ls' ...
#-------------------------------------------------------------
# Tailoring 'less'
#-------------------------------------------------------------
alias more='less'
export PAGER=less
export LESSCHARSET='latin1'
export LESSOPEN='|/usr/bin/lesspipe.sh %s 2&gt;&-'
# Use this if lesspipe.sh exists.
export LESS='-i -N -w -z-4 -g -e -M -X -F -R -P%t?f%f \
:stdin .?pb%pb\%:?lbLine %lb:?bbByte %bb:-...'
# LESS man page colors (makes Man pages more readable).
export LESS_TERMCAP_mb=$'\E[01;31m'
export LESS_TERMCAP_md=$'\E[01;31m'
export LESS_TERMCAP_me=$'\E[0m'
export LESS_TERMCAP_se=$'\E[0m'
export LESS_TERMCAP_so=$'\E[01;44;33m'
export LESS_TERMCAP_ue=$'\E[0m'
export LESS_TERMCAP_us=$'\E[01;32m'
#-------------------------------------------------------------
# Spelling typos - highly personnal and keyboard-dependent :-)
#-------------------------------------------------------------
alias xs='cd'
alias vf='cd'
alias moer='more'
alias moew='more'
alias kk='ll'
#-------------------------------------------------------------
# A few fun ones
#-------------------------------------------------------------
# Adds some text in the terminal frame (if applicable).
function xtitle()
{
case "$TERM" in
*term* | rxvt)
echo -en "\e]0;$*\a" ;;
*) ;;
esac
}
# Aliases that use xtitle
alias top='xtitle Processes on $HOST && top'
alias make='xtitle Making $(basename $PWD) ; make'
# .. and functions
function man()
{
for i ; do
xtitle The $(basename $1|tr -d .[:digit:]) manual
command man -a "$i"
done
}
#-------------------------------------------------------------
# Make the following commands run in background automatically:
#-------------------------------------------------------------
function te() # wrapper around xemacs/gnuserv
{
if [ "$(gnuclient -batch -eval t 2&gt;&-)" == "t" ]; then
gnuclient -q "$@";
else
( xemacs "$@" &);
fi
}
function soffice() { command soffice "$@" & }
function firefox() { command firefox "$@" & }
function xpdf() { command xpdf "$@" & }
#-------------------------------------------------------------
# File & strings related functions:
#-------------------------------------------------------------
# Find a file with a pattern in name:
function ff() { find . -type f -iname '*'"$*"'*' -ls ; }
# Find a file with pattern $1 in name and Execute $2 on it:
function fe() { find . -type f -iname '*'"${1:-}"'*' \
-exec ${2:-file} {} \; ; }
# Find a pattern in a set of files and highlight them:
#+ (needs a recent version of egrep).
function fstr()
{
OPTIND=1
local mycase=""
local usage="fstr: find string in files.
Usage: fstr [-i] \"pattern\" [\"filename pattern\"] "
while getopts :it opt
do
case "$opt" in
i) mycase="-i " ;;
*) echo "$usage"; return ;;
esac
done
shift $(( $OPTIND - 1 ))
if [ "$#" -lt 1 ]; then
echo "$usage"
return;
fi
find . -type f -name "${2:-*}" -print0 | \
xargs -0 egrep --color=always -sn ${case} "$1" 2&gt;&- | more
}
function swap()
{ # Swap 2 filenames around, if they exist (from Uzi's bashrc).
local TMPFILE=tmp.$$
[ $# -ne 2 ] && echo "swap: 2 arguments needed" && return 1
[ ! -e $1 ] && echo "swap: $1 does not exist" && return 1
[ ! -e $2 ] && echo "swap: $2 does not exist" && return 1
mv "$1" $TMPFILE
mv "$2" "$1"
mv $TMPFILE "$2"
}
function extract() # Handy Extract Program
{
if [ -f $1 ] ; then
case $1 in
*.tar.bz2) tar xvjf $1 ;;
*.tar.gz) tar xvzf $1 ;;
*.bz2) bunzip2 $1 ;;
*.rar) unrar x $1 ;;
*.gz) gunzip $1 ;;
*.tar) tar xvf $1 ;;
*.tbz2) tar xvjf $1 ;;
*.tgz) tar xvzf $1 ;;
*.zip) unzip $1 ;;
*.Z) uncompress $1 ;;
*.7z) 7z x $1 ;;
*) echo "'$1' cannot be extracted via &gt;extract<" ;;
esac
else
echo "'$1' is not a valid file!"
fi
}
# Creates an archive (*.tar.gz) from given directory.
function maketar() { tar cvzf "${1%%/}.tar.gz" "${1%%/}/"; }
# Create a ZIP archive of a file or folder.
function makezip() { zip -r "${1%%/}.zip" "$1" ; }
# Make your directories and files access rights sane.
function sanitize() { chmod -R u=rwX,g=rX,o= "$@" ;}
#-------------------------------------------------------------
# Process/system related functions:
#-------------------------------------------------------------
function my_ps() { ps $@ -u $USER -o pid,%cpu,%mem,bsdtime,command ; }
function pp() { my_ps f | awk '!/awk/ && $0~var' var=${1:-".*"} ; }
function killps() # kill by process name
{
local pid pname sig="-TERM" # default signal
if [ "$#" -lt 1 ] || [ "$#" -gt 2 ]; then
echo "Usage: killps [-SIGNAL] pattern"
return;
fi
if [ $# = 2 ]; then sig=$1 ; fi
for pid in $(my_ps| awk '!/awk/ && $0~pat { print $1 }' pat=${!#} )
do
pname=$(my_ps | awk '$1~var { print $5 }' var=$pid )
if ask "Kill process $pid <$pname&gt; with signal $sig?"
then kill $sig $pid
fi
done
}
function mydf() # Pretty-print of 'df' output.
{ # Inspired by 'dfc' utility.
for fs ; do
if [ ! -d $fs ]
then
echo -e $fs" :No such file or directory" ; continue
fi
local info=( $(command df -P $fs | awk 'END{ print $2,$3,$5 }') )
local free=( $(command df -Pkh $fs | awk 'END{ print $4 }') )
local nbstars=$(( 20 * ${info[1]} / ${info[0]} ))
local out="["
for ((j=0;j<20;j++)); do
if [ ${j} -lt ${nbstars} ]; then
out=$out"*"
else
out=$out"-"
fi
done
out=${info[2]}" "$out"] ("$free" free on "$fs")"
echo -e $out
done
}
function my_ip() # Get IP adress on ethernet.
{
MY_IP=$(/sbin/ifconfig eth0 | awk '/inet/ { print $2 } ' |
sed -e s/addr://)
echo ${MY_IP:-"Not connected"}
}
function ii() # Get current host related info.
{
echo -e "\nYou are logged on ${BRed}$HOST"
echo -e "\n${BRed}Additionnal information:$NC " ; uname -a
echo -e "\n${BRed}Users logged on:$NC " ; w -hs |
cut -d " " -f1 | sort | uniq
echo -e "\n${BRed}Current date :$NC " ; date
echo -e "\n${BRed}Machine stats :$NC " ; uptime
echo -e "\n${BRed}Memory stats :$NC " ; free
echo -e "\n${BRed}Diskspace :$NC " ; mydf / $HOME
echo -e "\n${BRed}Local IP Address :$NC" ; my_ip
echo -e "\n${BRed}Open connections :$NC "; netstat -pan --inet;
echo
}
#-------------------------------------------------------------
# Misc utilities:
#-------------------------------------------------------------
function repeat() # Repeat n times command.
{
local i max
max=$1; shift;
for ((i=1; i <= max ; i++)); do # --&gt; C-like syntax
eval "$@";
done
}
function ask() # See 'killps' for example of use.
{
echo -n "$@" '[y/n] ' ; read ans
case "$ans" in
y*|Y*) return 0 ;;
*) return 1 ;;
esac
}
function corename() # Get name of app that created a corefile.
{
for file ; do
echo -n $file : ; gdb --core=$file --batch | head -1
done
}
#=========================================================================
#
# PROGRAMMABLE COMPLETION SECTION
# Most are taken from the bash 2.05 documentation and from Ian McDonald's
# 'Bash completion' package (http://www.caliban.org/bash/#completion)
# You will in fact need bash more recent then 3.0 for some features.
#
# Note that most linux distributions now provide many completions
# 'out of the box' - however, you might need to make your own one day,
# so I kept those here as examples.
#=========================================================================
if [ "${BASH_VERSION%.*}" \< "3.0" ]; then
echo "You will need to upgrade to version 3.0 for full \
programmable completion features"
return
fi
shopt -s extglob # Necessary.
complete -A hostname rsh rcp telnet rlogin ftp ping disk
complete -A export printenv
complete -A variable export local readonly unset
complete -A enabled builtin
complete -A alias alias unalias
complete -A function function
complete -A user su mail finger
complete -A helptopic help # Currently same as builtins.
complete -A shopt shopt
complete -A stopped -P '%' bg
complete -A job -P '%' fg jobs disown
complete -A directory mkdir rmdir
complete -A directory -o default cd
# Compression
complete -f -o default -X '*.+(zip|ZIP)' zip
complete -f -o default -X '!*.+(zip|ZIP)' unzip
complete -f -o default -X '*.+(z|Z)' compress
complete -f -o default -X '!*.+(z|Z)' uncompress
complete -f -o default -X '*.+(gz|GZ)' gzip
complete -f -o default -X '!*.+(gz|GZ)' gunzip
complete -f -o default -X '*.+(bz2|BZ2)' bzip2
complete -f -o default -X '!*.+(bz2|BZ2)' bunzip2
complete -f -o default -X '!*.+(zip|ZIP|z|Z|gz|GZ|bz2|BZ2)' extract
# Documents - Postscript,pdf,dvi.....
complete -f -o default -X '!*.+(ps|PS)' gs ghostview ps2pdf ps2ascii
complete -f -o default -X \
'!*.+(dvi|DVI)' dvips dvipdf xdvi dviselect dvitype
complete -f -o default -X '!*.+(pdf|PDF)' acroread pdf2ps
complete -f -o default -X '!*.@(@(?(e)ps|?(E)PS|pdf|PDF)?\
(.gz|.GZ|.bz2|.BZ2|.Z))' gv ggv
complete -f -o default -X '!*.texi*' makeinfo texi2dvi texi2html texi2pdf
complete -f -o default -X '!*.tex' tex latex slitex
complete -f -o default -X '!*.lyx' lyx
complete -f -o default -X '!*.+(htm*|HTM*)' lynx html2ps
complete -f -o default -X \
'!*.+(doc|DOC|xls|XLS|ppt|PPT|sx?|SX?|csv|CSV|od?|OD?|ott|OTT)' soffice
# Multimedia
complete -f -o default -X \
'!*.+(gif|GIF|jp*g|JP*G|bmp|BMP|xpm|XPM|png|PNG)' xv gimp ee gqview
complete -f -o default -X '!*.+(mp3|MP3)' mpg123 mpg321
complete -f -o default -X '!*.+(ogg|OGG)' ogg123
complete -f -o default -X \
'!*.@(mp[23]|MP[23]|ogg|OGG|wav|WAV|pls|\
m3u|xm|mod|s[3t]m|it|mtm|ult|flac)' xmms
complete -f -o default -X '!*.@(mp?(e)g|MP?(E)G|wma|avi|AVI|\
asf|vob|VOB|bin|dat|vcd|ps|pes|fli|viv|rm|ram|yuv|mov|MOV|qt|\
QT|wmv|mp3|MP3|ogg|OGG|ogm|OGM|mp4|MP4|wav|WAV|asx|ASX)' xine
complete -f -o default -X '!*.pl' perl perl5
# This is a 'universal' completion function - it works when commands have
#+ a so-called 'long options' mode , ie: 'ls --all' instead of 'ls -a'
# Needs the '-o' option of grep
#+ (try the commented-out version if not available).
# First, remove '=' from completion word separators
#+ (this will allow completions like 'ls --color=auto' to work correctly).
COMP_WORDBREAKS=${COMP_WORDBREAKS/=/}
_get_longopts()
{
#$1 --help | sed -e '/--/!d' -e 's/.*--\([^[:space:].,]*\).*/--\1/'| \
#grep ^"$2" |sort -u ;
$1 --help | grep -o -e "--[^[:space:].,]*" | grep -e "$2" |sort -u
}
_longopts()
{
local cur
cur=${COMP_WORDS[COMP_CWORD]}
case "${cur:-*}" in
-*) ;;
*) return ;;
esac
case "$1" in
\~*) eval cmd="$1" ;;
*) cmd="$1" ;;
esac
COMPREPLY=( $(_get_longopts ${1} ${cur} ) )
}
complete -o default -F _longopts configure bash
complete -o default -F _longopts wget id info a2ps ls recode
_tar()
{
local cur ext regex tar untar
COMPREPLY=()
cur=${COMP_WORDS[COMP_CWORD]}
# If we want an option, return the possible long options.
case "$cur" in
-*) COMPREPLY=( $(_get_longopts $1 $cur ) ); return 0;;
esac
if [ $COMP_CWORD -eq 1 ]; then
COMPREPLY=( $( compgen -W 'c t x u r d A' -- $cur ) )
return 0
fi
case "${COMP_WORDS[1]}" in
?(-)c*f)
COMPREPLY=( $( compgen -f $cur ) )
return 0
;;
+([^Izjy])f)
ext='tar'
regex=$ext
;;
*z*f)
ext='tar.gz'
regex='t\(ar\.\)\(gz\|Z\)'
;;
*[Ijy]*f)
ext='t?(ar.)bz?(2)'
regex='t\(ar\.\)bz2\?'
;;
*)
COMPREPLY=( $( compgen -f $cur ) )
return 0
;;
esac
if [[ "$COMP_LINE" == tar*.$ext' '* ]]; then
# Complete on files in tar file.
#
# Get name of tar file from command line.
tar=$( echo "$COMP_LINE" | \
sed -e 's|^.* \([^ ]*'$regex'\) .*$|\1|' )
# Devise how to untar and list it.
untar=t${COMP_WORDS[1]//[^Izjyf]/}
COMPREPLY=( $( compgen -W "$( echo $( tar $untar $tar \
2&gt;/dev/null ) )" -- "$cur" ) )
return 0
else
# File completion on relevant files.
COMPREPLY=( $( compgen -G $cur\*.$ext ) )
fi
return 0
}
complete -F _tar -o default tar
_make()
{
local mdef makef makef_dir="." makef_inc gcmd cur prev i;
COMPREPLY=();
cur=${COMP_WORDS[COMP_CWORD]};
prev=${COMP_WORDS[COMP_CWORD-1]};
case "$prev" in
-*f)
COMPREPLY=($(compgen -f $cur ));
return 0
;;
esac;
case "$cur" in
-*)
COMPREPLY=($(_get_longopts $1 $cur ));
return 0
;;
esac;
# ... make reads
# GNUmakefile,
# then makefile
# then Makefile ...
if [ -f ${makef_dir}/GNUmakefile ]; then
makef=${makef_dir}/GNUmakefile
elif [ -f ${makef_dir}/makefile ]; then
makef=${makef_dir}/makefile
elif [ -f ${makef_dir}/Makefile ]; then
makef=${makef_dir}/Makefile
else
makef=${makef_dir}/*.mk # Local convention.
fi
# Before we scan for targets, see if a Makefile name was
#+ specified with -f.
for (( i=0; i < ${#COMP_WORDS[@]}; i++ )); do
if [[ ${COMP_WORDS[i]} == -f ]]; then
# eval for tilde expansion
eval makef=${COMP_WORDS[i+1]}
break
fi
done
[ ! -f $makef ] && return 0
# Deal with included Makefiles.
makef_inc=$( grep -E '^-?include' $makef |
sed -e "s,^.* ,"$makef_dir"/," )
for file in $makef_inc; do
[ -f $file ] && makef="$makef $file"
done
# If we have a partial word to complete, restrict completions
#+ to matches of that word.
if [ -n "$cur" ]; then gcmd='grep "^$cur"' ; else gcmd=cat ; fi
COMPREPLY=( $( awk -F':' '/^[a-zA-Z0-9][^$#\/\t=]*:([^=]|$)/ \
{split($1,A,/ /);for(i in A)print A[i]}' \
$makef 2&gt;/dev/null | eval $gcmd ))
}
complete -F _make -X '+($*|*.[cho])' make gmake pmake
_killall()
{
local cur prev
COMPREPLY=()
cur=${COMP_WORDS[COMP_CWORD]}
# Get a list of processes
#+ (the first sed evaluation
#+ takes care of swapped out processes, the second
#+ takes care of getting the basename of the process).
COMPREPLY=( $( ps -u $USER -o comm | \
sed -e '1,1d' -e 's#[]\[]##g' -e 's#^.*/##'| \
awk '{if ($0 ~ /^'$cur'/) print $0}' ))
return 0
}
complete -F _killall killall killps
# Local Variables:
# mode:shell-script
# sh-shell:bash
# End:
# From Andrzej Szelachowski's ~/.bash_profile:
# Note that a variable may require special treatment
#+ if it will be exported.
DARKGRAY='\e[1;30m'
LIGHTRED='\e[1;31m'
GREEN='\e[32m'
YELLOW='\e[1;33m'
LIGHTBLUE='\e[1;34m'
NC='\e[m'
PCT="\`if [[ \$EUID -eq 0 ]]; then T='$LIGHTRED' ; else T='$LIGHTBLUE'; fi;
echo \$T \`"
# For "literal" command substitution to be assigned to a variable,
#+ use escapes and double quotes:
#+ PCT="\` ... \`" . . .
# Otherwise, the value of PCT variable is assigned only once,
#+ when the variable is exported/read from .bash_profile,
#+ and it will not change afterwards even if the user ID changes.
PS1="\n$GREEN[\w] \n$DARKGRAY($PCT\t$DARKGRAY)-($PCT\u$DARKGRAY)-($PCT\!
$DARKGRAY)$YELLOW-&gt; $NC"
# Escape a variables whose value changes:
# if [[ \$EUID -eq 0 ]],
# Otherwise the value of the EUID variable will be assigned only once,
#+ as above.
# When a variable is assigned, it should be called escaped:
#+ echo \$T,
# Otherwise the value of the T variable is taken from the moment the PCT
#+ variable is exported/read from .bash_profile.
# So, in this example it would be null.
# When a variable's value contains a semicolon it should be strong quoted:
# T='$LIGHTRED',
# Otherwise, the semicolon will be interpreted as a command separator.
# Variables PCT and PS1 can be merged into a new PS1 variable:
PS1="\`if [[ \$EUID -eq 0 ]]; then PCT='$LIGHTRED';
else PCT='$LIGHTBLUE'; fi;
echo '\n$GREEN[\w] \n$DARKGRAY('\$PCT'\t$DARKGRAY)-\
('\$PCT'\u$DARKGRAY)-('\$PCT'\!$DARKGRAY)$YELLOW-&gt; $NC'\`"
# The trick is to use strong quoting for parts of old PS1 variable.</pre>]
#!/bin/bash
# numbers.sh: Representation of numbers in different bases.
# Decimal: the default
let "dec = 32"
echo "decimal number = $dec" # 32
# Nothing out of the ordinary here.
# Octal: numbers preceded by '0' (zero)
let "oct = 032"
echo "octal number = $oct" # 26
# Expresses result in decimal.
# --------- ------ -- -------
# Hexadecimal: numbers preceded by '0x' or '0X'
let "hex = 0x32"
echo "hexadecimal number = $hex" # 50
echo $((0x9abc)) # 39612
# ^^ ^^ double-parentheses arithmetic expansion/evaluation
# Expresses result in decimal.
# Other bases: BASE#NUMBER
# BASE between 2 and 64.
# NUMBER must use symbols within the BASE range, see below.
let "bin = 2#111100111001101"
echo "binary number = $bin" # 31181
let "b32 = 32#77"
echo "base-32 number = $b32" # 231
let "b64 = 64#@_"
echo "base-64 number = $b64" # 4031
# This notation only works for a limited range (2 - 64) of ASCII characters.
# 10 digits + 26 lowercase characters + 26 uppercase characters + @ + _
echo
echo $((36#zz)) $((2#10101010)) $((16#AF16)) $((53#1aA))
# 1295 170 44822 3375
# Important note:
# --------------
# Using a digit out of range of the specified base notation
#+ gives an error message.
let "bad_oct = 081"
# (Partial) error message output:
# bad_oct = 081: value too great for base (error token is "081")
# Octal numbers use only digits in the range 0 - 7.
exit $? # Exit value = 1 (error)
# Thanks, Rich Bartell and Stephane Chazelas, for clarification.</pre>]
#!/bin/bash
# Starting the script with "#!/bin/bash -r"
#+ runs entire script in restricted mode.
echo
echo "Changing directory."
cd /usr/local
echo "Now in `pwd`"
echo "Coming back home."
cd
echo "Now in `pwd`"
echo
# Everything up to here in normal, unrestricted mode.
set -r
# set --restricted has same effect.
echo "==&gt; Now in restricted mode. <=="
echo
echo
echo "Attempting directory change in restricted mode."
cd ..
echo "Still in `pwd`"
echo
echo
echo "\$SHELL = $SHELL"
echo "Attempting to change shell in restricted mode."
SHELL="/bin/ash"
echo
echo "\$SHELL= $SHELL"
echo
echo
echo "Attempting to redirect output in restricted mode."
ls -l /usr/bin &gt; bin.files
ls -l bin.files # Try to list attempted file creation effort.
echo
exit 0</pre>]
#!/bin/bash
for i in {1..10}
# Simpler and more straightforward than
#+ for i in $(seq 10)
do
echo -n "$i "
done
echo
# 1 2 3 4 5 6 7 8 9 10
# Or just . . .
echo {a..z} # a b c d e f g h i j k l m n o p q r s t u v w x y z
echo {e..m} # e f g h i j k l m
echo {z..a} # z y x w v u t s r q p o n m l k j i h g f e d c b a
# Works backwards, too.
echo {25..30} # 25 26 27 28 29 30
echo {3..-2} # 3 2 1 0 -1 -2
echo {X..d} # X Y Z [ ] ^ _ ` a b c d
# Shows (some of) the ASCII characters between Z and a,
#+ but don't rely on this type of behavior because . . .
echo {]..a} # {]..a}
# Why?
# You can tack on prefixes and suffixes.
echo "Number #"{1..4}, "..."
# Number #1, Number #2, Number #3, Number #4, ...
# You can concatenate brace-expansion sets.
echo {1..3}{x..z}" +" "..."
# 1x + 1y + 1z + 2x + 2y + 2z + 3x + 3y + 3z + ...
# Generates an algebraic expression.
# This could be used to find permutations.
# You can nest brace-expansion sets.
echo {{a..c},{1..3}}
# a b c 1 2 3
# The "comma operator" splices together strings.
# ########## ######### ############ ########### ######### ###############
# Unfortunately, brace expansion does not lend itself to parameterization.
var1=1
var2=5
echo {$var1..$var2} # {1..5}
# Yet, as Emiliano G. points out, using "eval" overcomes this limitation.
start=0
end=10
for index in $(eval echo {$start..$end})
do
echo -n "$index " # 0 1 2 3 4 5 6 7 8 9 10
done
echo
#!/bin/bash
Array=(element-zero element-one element-two element-three)
echo ${Array[0]} # element-zero
# First element of array.
echo ${!Array[@]} # 0 1 2 3
# All the indices of Array.
for i in ${!Array[@]}
do
echo ${Array[i]} # element-zero
# element-one
# element-two
# element-three
#
# All the elements in Array.
done
#!/bin/bash
variable="This is a fine mess."
echo "$variable"
# Regex matching with =~ operator within [[ double brackets ]].
if [[ "$variable" =~ T.........fin*es* ]]
# NOTE: As of version 3.2 of Bash, expression to match no longer quoted.
then
echo "match found"
# match found
fi
#!/bin/bash
input=$1
if [[ "$input" =~ "[0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9]" ]]
# ^ NOTE: Quoting not necessary, as of version 3.2 of Bash.
# NNN-NN-NNNN (where each N is a digit).
then
echo "Social Security number."
# Process SSN.
else
echo "Not a Social Security number!"
# Or, ask for corrected input.
fi
a=1
echo $a # 1
a+=5 # Won't work under versions of Bash earlier than 3.1.
echo $a # 15
a+=Hello
echo $a # 15Hello
a=1
echo $a # 1
let a+=5 # Integer arithmetic, rather than string concatenation.
echo $a # 6
let a+=Hello # Doesn't "add" anything to a.
echo $a # 6</pre>]
[]
[]
if [ -f $HOME/.Xclients ]; then
exec $HOME/.Xclients
elif [ -f /etc/X11/xinit/Xclients ]; then
exec /etc/X11/xinit/Xclients
else
# failsafe settings. Although we should never get here
# (we provide fallbacks in Xclients as well) it can't hurt.
xclock -geometry 100x100-5+5 &
xterm -geometry 80x50-50+150 &
if [ -f /usr/bin/netscape -a -f /usr/share/doc/HTML/index.html ]; then
netscape /usr/share/doc/HTML/index.html &
fi
fi</pre>]
[]
#!/bin/bash
# Redirecting stdin using 'exec'.
exec 6<&0 # Link file descriptor #6 with stdin.
# Saves stdin.
exec < data-file # stdin replaced by file "data-file"
read a1 # Reads first line of file "data-file".
read a2 # Reads second line of file "data-file."
echo
echo "Following lines read from file."
echo "-------------------------------"
echo $a1
echo $a2
echo; echo; echo
exec 0<&6 6<&-
# Now restore stdin from fd #6, where it had been saved,
#+ and close fd #6 ( 6<&- ) to free it for other processes to use.
#
# <&6 6<&- also works.
echo -n "Enter data "
read b1 # Now "read" functions as expected, reading from normal stdin.
echo "Input read from stdin."
echo "----------------------"
echo "b1 = $b1"
echo
exit 0
#!/bin/bash
# reassign-stdout.sh
LOGFILE=logfile.txt
exec 6&gt;&1 # Link file descriptor #6 with stdout.
# Saves stdout.
exec &gt; $LOGFILE # stdout replaced with file "logfile.txt".
# ----------------------------------------------------------- #
# All output from commands in this block sent to file $LOGFILE.
echo -n "Logfile: "
date
echo "-------------------------------------"
echo
echo "Output of \"ls -al\" command"
echo
ls -al
echo; echo
echo "Output of \"df\" command"
echo
df
# ----------------------------------------------------------- #
exec 1&gt;&6 6&gt;&- # Restore stdout and close file descriptor #6.
echo
echo "== stdout now restored to default == "
echo
ls -al
echo
exit 0
#!/bin/bash
# upperconv.sh
# Converts a specified input file to uppercase.
E_FILE_ACCESS=70
E_WRONG_ARGS=71
if [ ! -r "$1" ] # Is specified input file readable?
then
echo "Can't read from input file!"
echo "Usage: $0 input-file output-file"
exit $E_FILE_ACCESS
fi # Will exit with same error
#+ even if input file ($1) not specified (why?).
if [ -z "$2" ]
then
echo "Need to specify output file."
echo "Usage: $0 input-file output-file"
exit $E_WRONG_ARGS
fi
exec 4<&0
exec < $1 # Will read from input file.
exec 7&gt;&1
exec &gt; $2 # Will write to output file.
# Assumes output file writable (add check?).
# -----------------------------------------------
cat - | tr a-z A-Z # Uppercase conversion.
# ^^^^^ # Reads from stdin.
# ^^^^^^^^^^ # Writes to stdout.
# However, both stdin and stdout were redirected.
# Note that the 'cat' can be omitted.
# -----------------------------------------------
exec 1&gt;&7 7&gt;&- # Restore stout.
exec 0<&4 4<&- # Restore stdin.
# After restoration, the following line prints to stdout as expected.
echo "File \"$1\" written to \"$2\" as uppercase conversion."
exit 0
#!/bin/bash
# avoid-subshell.sh
# Suggested by Matthew Walker.
Lines=0
echo
cat myfile.txt | while read line;
do {
echo $line
(( Lines++ )); # Incremented values of this variable
#+ inaccessible outside loop.
# Subshell problem.
}
done
echo "Number of lines read = $Lines" # 0
# Wrong!
echo "------------------------"
exec 3<&gt; myfile.txt
while read line <&3
do {
echo "$line"
(( Lines++ )); # Incremented values of this variable
#+ accessible outside loop.
# No subshell, no problem.
}
done
exec 3&gt;&-
echo "Number of lines read = $Lines" # 8
echo
exit 0
# Lines below not seen by script.
$ cat myfile.txt
Line 1.
Line 2.
Line 3.
Line 4.
Line 5.
Line 6.
Line 7.
Line 8.</pre>]
#!/bin/bash
# primes2.sh
# Generating prime numbers the quick-and-easy way,
#+ without resorting to fancy algorithms.
CEILING=10000 # 1 to 10000
PRIME=0
E_NOTPRIME=
is_prime ()
{
local factors
factors=( $(factor $1) ) # Load output of `factor` into array.
if [ -z "${factors[2]}" ]
# Third element of "factors" array:
#+ ${factors[2]} is 2nd factor of argument.
# If it is blank, then there is no 2nd factor,
#+ and the argument is therefore prime.
then
return $PRIME # 0
else
return $E_NOTPRIME # null
fi
}
echo
for n in $(seq $CEILING)
do
if is_prime $n
then
printf %5d $n
fi # ^ Five positions per number suffices.
done # For a higher $CEILING, adjust upward, as necessary.
echo
exit
#!/bin/bash
# monthlypmt.sh: Calculates monthly payment on a mortgage.
# This is a modification of code in the
#+ "mcalc" (mortgage calculator) package,
#+ by Jeff Schmidt
#+ and
#+ Mendel Cooper (yours truly, the ABS Guide author).
# http://www.ibiblio.org/pub/Linux/apps/financial/mcalc-1.6.tar.gz
echo
echo "Given the principal, interest rate, and term of a mortgage,"
echo "calculate the monthly payment."
bottom=1.0
echo
echo -n "Enter principal (no commas) "
read principal
echo -n "Enter interest rate (percent) " # If 12%, enter "12", not ".12".
read interest_r
echo -n "Enter term (months) "
read term
interest_r=$(echo "scale=9; $interest_r/100.0" | bc) # Convert to decimal.
# ^^^^^^^^^^^^^^^^^ Divide by 100.
# "scale" determines how many decimal places.
interest_rate=$(echo "scale=9; $interest_r/12 + 1.0" | bc)
top=$(echo "scale=9; $principal*$interest_rate^$term" | bc)
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
# Standard formula for figuring interest.
echo; echo "Please be patient. This may take a while."
let "months = $term - 1"
# ====================================================================
for ((x=$months; x &gt; 0; x--))
do
bot=$(echo "scale=9; $interest_rate^$x" | bc)
bottom=$(echo "scale=9; $bottom+$bot" | bc)
# bottom = $(($bottom + $bot"))
done
# ====================================================================
# --------------------------------------------------------------------
# Rick Boivie pointed out a more efficient implementation
#+ of the above loop, which decreases computation time by 2/3.
# for ((x=1; x <= $months; x++))
# do
# bottom=$(echo "scale=9; $bottom * $interest_rate + 1" | bc)
# done
# And then he came up with an even more efficient alternative,
#+ one that cuts down the run time by about 95%!
# bottom=`{
# echo "scale=9; bottom=$bottom; interest_rate=$interest_rate"
# for ((x=1; x <= $months; x++))
# do
# echo 'bottom = bottom * interest_rate + 1'
# done
# echo 'bottom'
# } | bc` # Embeds a 'for loop' within command substitution.
# --------------------------------------------------------------------------
# On the other hand, Frank Wang suggests:
# bottom=$(echo "scale=9; ($interest_rate^$term-1)/($interest_rate-1)" | bc)
# Because . . .
# The algorithm behind the loop
#+ is actually a sum of geometric proportion series.
# The sum formula is e0(1-q^n)/(1-q),
#+ where e0 is the first element and q=e(n+1)/e(n)
#+ and n is the number of elements.
# --------------------------------------------------------------------------
# let "payment = $top/$bottom"
payment=$(echo "scale=2; $top/$bottom" | bc)
# Use two decimal places for dollars and cents.
echo
echo "monthly payment = \$$payment" # Echo a dollar sign in front of amount.
echo
exit 0
# Exercises:
# 1) Filter input to permit commas in principal amount.
# 2) Filter input to permit interest to be entered as percent or decimal.
# 3) If you are really ambitious,
#+ expand this script to print complete amortization tables.
#!/bin/bash
###########################################################################
# Shellscript: base.sh - print number to different bases (Bourne Shell)
# Author : Heiner Steven (heiner.steven@odn.de)
# Date : 07-03-95
# Category : Desktop
# $Id: base.sh,v 1.2 2000/02/06 19:55:35 heiner Exp $
# ==&gt; Above line is RCS ID info.
###########################################################################
# Description
#
# Changes
# 21-03-95 stv fixed error occuring with 0xb as input (0.2)
###########################################################################
# ==&gt; Used in ABS Guide with the script author's permission.
# ==&gt; Comments added by ABS Guide author.
NOARGS=85
PN=`basename "$0"` # Program name
VER=`echo '$Revision: 1.2 $' | cut -d' ' -f2` # ==&gt; VER=1.2
Usage () {
echo "$PN - print number to different bases, $VER (stv '95)
usage: $PN [number ...]
If no number is given, the numbers are read from standard input.
A number may be
binary (base 2) starting with 0b (i.e. 0b1100)
octal (base 8) starting with 0 (i.e. 014)
hexadecimal (base 16) starting with 0x (i.e. 0xc)
decimal otherwise (i.e. 12)" &gt;&2
exit $NOARGS
} # ==&gt; Prints usage message.
Msg () {
for i # ==&gt; in [list] missing. Why?
do echo "$PN: $i" &gt;&2
done
}
Fatal () { Msg "$@"; exit 66; }
PrintBases () {
# Determine base of the number
for i # ==&gt; in [list] missing...
do # ==&gt; so operates on command-line arg(s).
case "$i" in
0b*) ibase=2;; # binary
0x*|[a-f]*|[A-F]*) ibase=16;; # hexadecimal
0*) ibase=8;; # octal
[1-9]*) ibase=10;; # decimal
*)
Msg "illegal number $i - ignored"
continue;;
esac
# Remove prefix, convert hex digits to uppercase (bc needs this).
number=`echo "$i" | sed -e 's:^0[bBxX]::' | tr '[a-f]' '[A-F]'`
# ==&gt; Uses ":" as sed separator, rather than "/".
# Convert number to decimal
dec=`echo "ibase=$ibase; $number" | bc` # ==&gt; 'bc' is calculator utility.
case "$dec" in
[0-9]*) ;; # number ok
*) continue;; # error: ignore
esac
# Print all conversions in one line.
# ==&gt; 'here document' feeds command list to 'bc'.
echo `bc <<!
obase=16; "hex="; $dec
obase=10; "dec="; $dec
obase=8; "oct="; $dec
obase=2; "bin="; $dec
!
` | sed -e 's: : :g'
done
}
while [ $# -gt 0 ]
# ==&gt; Is a "while loop" really necessary here,
# ==&gt;+ since all the cases either break out of the loop
# ==&gt;+ or terminate the script.
# ==&gt; (Above comment by Paulo Marcel Coelho Aragao.)
do
case "$1" in
--) shift; break;;
-h) Usage;; # ==&gt; Help message.
-*) Usage;;
*) break;; # First number
esac # ==&gt; Error checking for illegal input might be appropriate.
shift
done
if [ $# -gt 0 ]
then
PrintBases "$@"
else # Read from stdin.
while read line
do
PrintBases $line
done
fi
exit
variable=`bc << LIMIT_STRING
options
statements
operations
LIMIT_STRING
`
...or...
variable=$(bc << LIMIT_STRING
options
statements
operations
LIMIT_STRING
)
#!/bin/bash
# Invoking 'bc' using command substitution
# in combination with a 'here document'.
var1=`bc << EOF
18.33 * 19.78
EOF
`
echo $var1 # 362.56
# $( ... ) notation also works.
v1=23.53
v2=17.881
v3=83.501
v4=171.63
var2=$(bc << EOF
scale = 4
a = ( $v1 + $v2 )
b = ( $v3 * $v4 )
a * b + 15.35
EOF
)
echo $var2 # 593487.8452
var3=$(bc -l << EOF
scale = 9
s ( 1.7 )
EOF
)
# Returns the sine of 1.7 radians.
# The "-l" option calls the 'bc' math library.
echo $var3 # .991664810
# Now, try it in a function...
hypotenuse () # Calculate hypotenuse of a right triangle.
{ # c = sqrt( a^2 + b^2 )
hyp=$(bc -l << EOF
scale = 9
sqrt ( $1 * $1 + $2 * $2 )
EOF
)
# Can't directly return floating point values from a Bash function.
# But, can echo-and-capture:
echo "$hyp"
}
hyp=$(hypotenuse 3.68 7.31)
echo "hypotenuse = $hyp" # 8.184039344
exit 0
#!/bin/bash
# cannon.sh: Approximating PI by firing cannonballs.
# Author: Mendel Cooper
# License: Public Domain
# Version 2.2, reldate 13oct08.
# This is a very simple instance of a "Monte Carlo" simulation:
#+ a mathematical model of a real-life event,
#+ using pseudorandom numbers to emulate random chance.
# Consider a perfectly square plot of land, 10000 units on a side.
# This land has a perfectly circular lake in its center,
#+ with a diameter of 10000 units.
# The plot is actually mostly water, except for land in the four corners.
# (Think of it as a square with an inscribed circle.)
#
# We will fire iron cannonballs from an old-style cannon
#+ at the square.
# All the shots impact somewhere on the square,
#+ either in the lake or on the dry corners.
# Since the lake takes up most of the area,
#+ most of the shots will SPLASH! into the water.
# Just a few shots will THUD! into solid ground
#+ in the four corners of the square.
#
# If we take enough random, unaimed shots at the square,
#+ Then the ratio of SPLASHES to total shots will approximate
#+ the value of PI/4.
#
# The simplified explanation is that the cannon is actually
#+ shooting only at the upper right-hand quadrant of the square,
#+ i.e., Quadrant I of the Cartesian coordinate plane.
#
#
# Theoretically, the more shots taken, the better the fit.
# However, a shell script, as opposed to a compiled language
#+ with floating-point math built in, requires some compromises.
# This decreases the accuracy of the simulation.
DIMENSION=10000 # Length of each side of the plot.
# Also sets ceiling for random integers generated.
MAXSHOTS=1000 # Fire this many shots.
# 10000 or more would be better, but would take too long.
PMULTIPLIER=4.0 # Scaling factor.
declare -r M_PI=3.141592654
# Actual 9-place value of PI, for comparison purposes.
get_random ()
{
SEED=$(head -n 1 /dev/urandom | od -N 1 | awk '{ print $2 }')
RANDOM=$SEED # From "seeding-random.sh"
#+ example script.
let "rnum = $RANDOM % $DIMENSION" # Range less than 10000.
echo $rnum
}
distance= # Declare global variable.
hypotenuse () # Calculate hypotenuse of a right triangle.
{ # From "alt-bc.sh" example.
distance=$(bc -l << EOF
scale = 0
sqrt ( $1 * $1 + $2 * $2 )
EOF
)
# Setting "scale" to zero rounds down result to integer value,
#+ a necessary compromise in this script.
# It decreases the accuracy of this simulation.
}
# ==========================================================
# main() {
# "Main" code block, mimicking a C-language main() function.
# Initialize variables.
shots=0
splashes=0
thuds=0
Pi=0
error=0
while [ "$shots" -lt "$MAXSHOTS" ] # Main loop.
do
xCoord=$(get_random) # Get random X and Y coords.
yCoord=$(get_random)
hypotenuse $xCoord $yCoord # Hypotenuse of
#+ right-triangle = distance.
((shots++))
printf "#%4d " $shots
printf "Xc = %4d " $xCoord
printf "Yc = %4d " $yCoord
printf "Distance = %5d " $distance # Distance from
#+ center of lake
#+ -- the "origin" --
#+ coordinate (0,0).
if [ "$distance" -le "$DIMENSION" ]
then
echo -n "SPLASH! "
((splashes++))
else
echo -n "THUD! "
((thuds++))
fi
Pi=$(echo "scale=9; $PMULTIPLIER*$splashes/$shots" | bc)
# Multiply ratio by 4.0.
echo -n "PI ~ $Pi"
echo
done
echo
echo "After $shots shots, PI looks like approximately $Pi"
# Tends to run a bit high,
#+ possibly due to round-off error and imperfect randomness of $RANDOM.
# But still usually within plus-or-minus 5% . . .
#+ a pretty fair rough approximation.
error=$(echo "scale=9; $Pi - $M_PI" | bc)
pct_error=$(echo "scale=2; 100.0 * $error / $M_PI" | bc)
echo -n "Deviation from mathematical value of PI = $error"
echo " ($pct_error% error)"
echo
# End of "main" code block.
# }
# ==========================================================
exit 0
# One might well wonder whether a shell script is appropriate for
#+ an application as complex and computation-intensive as a simulation.
#
# There are at least two justifications.
# 1) As a proof of concept: to show it can be done.
# 2) To prototype and test the algorithms before rewriting
#+ it in a compiled high-level language.
echo "[Printing a string ... ]P" | dc
# The P command prints the string between the preceding brackets.
# And now for some simple arithmetic.
echo "7 8 * p" | dc # 56
# Pushes 7, then 8 onto the stack,
#+ multiplies ("*" operator), then prints the result ("p" operator).
#!/bin/bash
# hexconvert.sh: Convert a decimal number to hexadecimal.
E_NOARGS=85 # Command-line arg missing.
BASE=16 # Hexadecimal.
if [ -z "$1" ]
then # Need a command-line argument.
echo "Usage: $0 number"
exit $E_NOARGS
fi # Exercise: add argument validity checking.
hexcvt ()
{
if [ -z "$1" ]
then
echo 0
return # "Return" 0 if no arg passed to function.
fi
echo ""$1" "$BASE" o p" | dc
# o sets radix (numerical base) of output.
# p prints the top of stack.
# For other options: 'man dc' ...
return
}
hexcvt "$1"
exit
dc <<< 10k5v1+2/p # 1.6180339887
# ^^^ Feed operations to dc using a Here String.
# ^^^ Pushes 10 and sets that as the precision (10k).
# ^^ Pushes 5 and takes its square root
# (5v, v = square root).
# ^^ Pushes 1 and adds it to the running total (1+).
# ^^ Pushes 2 and divides the running total by that (2/).
# ^ Pops and prints the result (p)
# The result is 1.6180339887 ...
# ... which happens to be the Pythagorean Golden Ratio, to 10 places.
#!/bin/bash
# factr.sh: Factor a number
MIN=2 # Will not work for number smaller than this.
E_NOARGS=85
E_TOOSMALL=86
if [ -z $1 ]
then
echo "Usage: $0 number"
exit $E_NOARGS
fi
if [ "$1" -lt "$MIN" ]
then
echo "Number to factor must be $MIN or greater."
exit $E_TOOSMALL
fi
# Exercise: Add type checking (to reject non-integer arg).
echo "Factors of $1:"
# -------------------------------------------------------
echo "$1[p]s2[lip/dli%0=1dvsr]s12sid2%0=13sidvsr[dli%0=\
1lrli2+dsi!&gt;.]ds.xd1<2" | dc
# -------------------------------------------------------
# Above code written by Michel Charpentier <charpov@cs.unh.edu&gt;
# (as a one-liner, here broken into two lines for display purposes).
# Used in ABS Guide with permission (thanks!).
exit
# $ sh factr.sh 270138
# 2
# 3
# 11
# 4093
#!/bin/bash
# hypotenuse.sh: Returns the "hypotenuse" of a right triangle.
# (square root of sum of squares of the "legs")
ARGS=2 # Script needs sides of triangle passed.
E_BADARGS=85 # Wrong number of arguments.
if [ $# -ne "$ARGS" ] # Test number of arguments to script.
then
echo "Usage: `basename $0` side_1 side_2"
exit $E_BADARGS
fi
AWKSCRIPT=' { printf( "%3.7f\n", sqrt($1*$1 + $2*$2) ) } '
# command(s) / parameters passed to awk
# Now, pipe the parameters to awk.
echo -n "Hypotenuse of $1 and $2 = "
echo $1 $2 | awk "$AWKSCRIPT"
# ^^^^^^^^^^^^
# An echo-and-pipe is an easy way of passing shell parameters to awk.
exit
# Exercise: Rewrite this script using 'bc' rather than awk.
# Which method is more intuitive?</pre>]
#!/bin/bash
# Naked variables
echo
# When is a variable "naked", i.e., lacking the '$' in front?
# When it is being assigned, rather than referenced.
# Assignment
a=879
echo "The value of \"a\" is $a."
# Assignment using 'let'
let a=16+5
echo "The value of \"a\" is now $a."
echo
# In a 'for' loop (really, a type of disguised assignment):
echo -n "Values of \"a\" in the loop are: "
for a in 7 8 9 11
do
echo -n "$a "
done
echo
echo
# In a 'read' statement (also a type of assignment):
echo -n "Enter \"a\" "
read a
echo "The value of \"a\" is now $a."
echo
exit 0
#!/bin/bash
a=23 # Simple case
echo $a
b=$a
echo $b
# Now, getting a little bit fancier (command substitution).
a=`echo Hello!` # Assigns result of 'echo' command to 'a' ...
echo $a
# Note that including an exclamation mark (!) within a
#+ command substitution construct will not work from the command-line,
#+ since this triggers the Bash "history mechanism."
# Inside a script, however, the history functions are disabled by default.
a=`ls -l` # Assigns result of 'ls -l' command to 'a'
echo $a # Unquoted, however, it removes tabs and newlines.
echo
echo "$a" # The quoted variable preserves whitespace.
# (See the chapter on "Quoting.")
exit 0
# From /etc/rc.d/rc.local
R=$(cat /etc/redhat-release)
arch=$(uname -m)</pre>]
[]
[]
sed -e '/^$/d' $filename
# The -e option causes the next string to be interpreted as an editing instruction.
# (If passing only a single instruction to sed, the "-e" is optional.)
# The "strong" quotes ('') protect the RE characters in the instruction
#+ from reinterpretation as special characters by the body of the script.
# (This reserves RE expansion of the instruction for sed.)
#
# Operates on the text contained in file $filename.
filename=file1.txt
pattern=BEGIN
sed "/^$pattern/d" "$filename" # Works as specified.
# sed '/^$pattern/d' "$filename" has unexpected results.
# In this instance, with strong quoting (' ... '),
#+ "$pattern" will not expand to "BEGIN".
sed -n '/xzy/p' $filename
# The -n option tells sed to print only those lines matching the pattern.
# Otherwise all input lines would print.
# The -e option not necessary here since there is only a single editing instruction.
s/^ */\
/g
/[0-9A-Za-z]/,/^$/{
/^$/d
}</pre>]
[]
#!/bin/bash
# Testing ranges of characters.
echo; echo "Hit a key, then hit return."
read Keypress
case "$Keypress" in
[[:lower:]] ) echo "Lowercase letter";;
[[:upper:]] ) echo "Uppercase letter";;
[0-9] ) echo "Digit";;
* ) echo "Punctuation, whitespace, or other";;
esac # Allows ranges of characters in [square brackets],
#+ or POSIX ranges in [[double square brackets.
# In the first version of this example,
#+ the tests for lowercase and uppercase characters were
#+ [a-z] and [A-Z].
# This no longer works in certain locales and/or Linux distros.
# POSIX is more portable.
# Thanks to Frank Wang for pointing this out.
# Exercise:
# --------
# As the script stands, it accepts a single keystroke, then terminates.
# Change the script so it accepts repeated input,
#+ reports on each keystroke, and terminates only when "X" is hit.
# Hint: enclose everything in a "while" loop.
exit 0
#!/bin/bash
# Crude address database
clear # Clear the screen.
echo " Contact List"
echo " ------- ----"
echo "Choose one of the following persons:"
echo
echo "[E]vans, Roland"
echo "[J]ones, Mildred"
echo "[S]mith, Julie"
echo "[Z]ane, Morris"
echo
read person
case "$person" in
# Note variable is quoted.
"E" | "e" )
# Accept upper or lowercase input.
echo
echo "Roland Evans"
echo "4321 Flash Dr."
echo "Hardscrabble, CO 80753"
echo "(303) 734-9874"
echo "(303) 734-9892 fax"
echo "revans@zzy.net"
echo "Business partner & old friend"
;;
# Note double semicolon to terminate each option.
"J" | "j" )
echo
echo "Mildred Jones"
echo "249 E. 7th St., Apt. 19"
echo "New York, NY 10009"
echo "(212) 533-2814"
echo "(212) 533-9972 fax"
echo "milliej@loisaida.com"
echo "Ex-girlfriend"
echo "Birthday: Feb. 11"
;;
# Add info for Smith & Zane later.
* )
# Default option.
# Empty input (hitting RETURN) fits here, too.
echo
echo "Not yet in database."
;;
esac
echo
# Exercise:
# --------
# Change the script so it accepts multiple inputs,
#+ instead of terminating after displaying just one address.
exit 0
#! /bin/bash
case "$1" in
"") echo "Usage: ${0##*/} <filename&gt;"; exit $E_PARAM;;
# No command-line parameters,
# or first parameter empty.
# Note that ${0##*/} is ${var##pattern} param substitution.
# Net result is $0.
-*) FILENAME=./$1;; # If filename passed as argument ($1)
#+ starts with a dash,
#+ replace it with ./$1
#+ so further commands don't interpret it
#+ as an option.
* ) FILENAME=$1;; # Otherwise, $1.
esac
#! /bin/bash
while [ $# -gt 0 ]; do # Until you run out of parameters . . .
case "$1" in
-d|--debug)
# "-d" or "--debug" parameter?
DEBUG=1
;;
-c|--conf)
CONFFILE="$2"
shift
if [ ! -f $CONFFILE ]; then
echo "Error: Supplied file doesn't exist!"
exit $E_CONFFILE # File not found error.
fi
;;
esac
shift # Check next set of parameters.
done
# From Stefano Falsetto's "Log2Rot" script,
#+ part of his "rottlog" package.
# Used with permission.
#!/bin/bash
# case-cmd.sh: Using command substitution to generate a "case" variable.
case $( arch ) in # $( arch ) returns machine architecture.
# Equivalent to 'uname -m' ...
i386 ) echo "80386-based machine";;
i486 ) echo "80486-based machine";;
i586 ) echo "Pentium-based machine";;
i686 ) echo "Pentium2+-based machine";;
* ) echo "Other type of machine";;
esac
exit 0
#!/bin/bash
# match-string.sh: Simple string matching
# using a 'case' construct.
match_string ()
{ # Exact string match.
MATCH=0
E_NOMATCH=90
PARAMS=2 # Function requires 2 arguments.
E_BAD_PARAMS=91
[ $# -eq $PARAMS ] || return $E_BAD_PARAMS
case "$1" in
"$2") return $MATCH;;
* ) return $E_NOMATCH;;
esac
}
a=one
b=two
c=three
d=two
match_string $a # wrong number of parameters
echo $? # 91
match_string $a $b # no match
echo $? # 90
match_string $b $d # match
echo $? # 0
exit 0
#!/bin/bash
# isalpha.sh: Using a "case" structure to filter a string.
SUCCESS=0
FAILURE=1 # Was FAILURE=-1,
#+ but Bash no longer allows negative return value.
isalpha () # Tests whether *first character* of input string is alphabetic.
{
if [ -z "$1" ] # No argument passed?
then
return $FAILURE
fi
case "$1" in
[a-zA-Z]*) return $SUCCESS;; # Begins with a letter?
* ) return $FAILURE;;
esac
} # Compare this with "isalpha ()" function in C.
isalpha2 () # Tests whether *entire string* is alphabetic.
{
[ $# -eq 1 ] || return $FAILURE
case $1 in
*[!a-zA-Z]*|"") return $FAILURE;;
*) return $SUCCESS;;
esac
}
isdigit () # Tests whether *entire string* is numerical.
{ # In other words, tests for integer variable.
[ $# -eq 1 ] || return $FAILURE
case $1 in
*[!0-9]*|"") return $FAILURE;;
*) return $SUCCESS;;
esac
}
check_var () # Front-end to isalpha ().
{
if isalpha "$@"
then
echo "\"$*\" begins with an alpha character."
if isalpha2 "$@"
then # No point in testing if first char is non-alpha.
echo "\"$*\" contains only alpha characters."
else
echo "\"$*\" contains at least one non-alpha character."
fi
else
echo "\"$*\" begins with a non-alpha character."
# Also "non-alpha" if no argument passed.
fi
echo
}
digit_check () # Front-end to isdigit ().
{
if isdigit "$@"
then
echo "\"$*\" contains only digits [0 - 9]."
else
echo "\"$*\" has at least one non-digit character."
fi
echo
}
a=23skidoo
b=H3llo
c=-What?
d=What?
e=$(echo $b) # Command substitution.
f=AbcDef
g=27234
h=27a34
i=27.34
check_var $a
check_var $b
check_var $c
check_var $d
check_var $e
check_var $f
check_var # No argument passed, so what happens?
#
digit_check $g
digit_check $h
digit_check $i
exit 0 # Script improved by S.C.
# Exercise:
# --------
# Write an 'isfloat ()' function that tests for floating point numbers.
# Hint: The function duplicates 'isdigit ()',
#+ but adds a test for a mandatory decimal point.
#!/bin/bash
PS3='Choose your favorite vegetable: ' # Sets the prompt string.
# Otherwise it defaults to #? .
echo
select vegetable in "beans" "carrots" "potatoes" "onions" "rutabagas"
do
echo
echo "Your favorite veggie is $vegetable."
echo "Yuck!"
echo
break # What happens if there is no 'break' here?
done
exit
# Exercise:
# --------
# Fix this script to accept user input not specified in
#+ the "select" statement.
# For example, if the user inputs "peas,"
#+ the script would respond "Sorry. That is not on the menu."
#!/bin/bash
PS3='Choose your favorite vegetable: '
echo
choice_of()
{
select vegetable
# [in list] omitted, so 'select' uses arguments passed to function.
do
echo
echo "Your favorite veggie is $vegetable."
echo "Yuck!"
echo
break
done
}
choice_of beans rice carrots radishes rutabaga spinach
# $1 $2 $3 $4 $5 $6
# passed to choice_of() function
exit 0
case $( arch ) in # $( arch ) returns machine architecture.
( i386 ) echo "80386-based machine";;
# ^ ^
( i486 ) echo "80486-based machine";;
( i586 ) echo "Pentium-based machine";;
( i686 ) echo "Pentium2+-based machine";;
( * ) echo "Other type of machine";;
esac</pre>]
[]
PASS="$PASS${MATRIX:$(($RANDOM%${#MATRIX})):1}"
# It made perfect sense when you wrote it last year,
#+ but now it's a complete mystery.
# (From Antek Sawicki's "pw.sh" script.)
#!/bin/bash
#************************************************#
# xyz.sh #
# written by Bozo Bozeman #
# July 05, 2001 #
# #
# Clean up project files. #
#************************************************#
E_BADDIR=85 # No such directory.
projectdir=/home/bozo/projects # Directory to clean up.
# --------------------------------------------------------- #
# cleanup_pfiles () #
# Removes all files in designated directory. #
# Parameter: $target_directory #
# Returns: 0 on success, $E_BADDIR if something went wrong. #
# --------------------------------------------------------- #
cleanup_pfiles ()
{
if [ ! -d "$1" ] # Test if target directory exists.
then
echo "$1 is not a directory."
return $E_BADDIR
fi
rm -f "$1"/*
return 0 # Success.
}
cleanup_pfiles $projectdir
exit $?
if [ -f /var/log/messages ]
then
...
fi
# A year later, you decide to change the script to check /var/log/syslog.
# It is now necessary to manually change the script, instance by instance,
#+ and hope nothing breaks.
# A better way:
LOGFILE=/var/log/messages # Only line that needs to be changed.
if [ -f "$LOGFILE" ]
then
...
fi
fl=`ls -al $dirname` # Cryptic.
file_listing=`ls -al $dirname` # Better.
MAXVAL=10 # All caps used for a script constant.
while [ "$index" -le "$MAXVAL" ]
...
E_NOTFOUND=95 # Uppercase for an errorcode,
#+ and name prefixed with E_.
if [ ! -e "$filename" ]
then
echo "File $filename not found."
exit $E_NOTFOUND
fi
MAIL_DIRECTORY=/var/spool/mail/bozo # Uppercase for an environmental
export MAIL_DIRECTORY #+ variable.
GetAnswer () # Mixed case works well for a
{ #+ function name, especially
prompt=$1 #+ when it improves legibility.
echo -n $prompt
read answer
return $answer
}
GetAnswer "What is your favorite number? "
favorite_number=$?
echo $favorite_number
_uservariable=23 # Permissible, but not recommended.
# It's better for user-defined variables not to start with an underscore.
# Leave that for system variables.
E_WRONG_ARGS=95
...
...
exit $E_WRONG_ARGS
-a All: Return all information (including hidden file info).
-b Brief: Short version, usually for other scripts.
-c Copy, concatenate, etc.
-d Daily: Use information from the whole day, and not merely
information for a specific instance/user.
-e Extended/Elaborate: (often does not include hidden file info).
-h Help: Verbose usage w/descs, aux info, discussion, help.
See also -V.
-l Log output of script.
-m Manual: Launch man-page for base command.
-n Numbers: Numerical data only.
-r Recursive: All files in a directory (and/or all sub-dirs).
-s Setup & File Maintenance: Config files for this script.
-u Usage: List of invocation flags for the script.
-v Verbose: Human readable output, more or less formatted.
-V Version / License / Copy(right|left) / Contribs (email too).
COMMAND
if [ $? -eq 0 ]
...
# Redundant and non-intuitive.
if COMMAND
...
# More concise (if perhaps not quite as legible).</pre>]
REM VIEWDATA
REM INSPIRED BY AN EXAMPLE IN "DOS POWERTOOLS"
REM BY PAUL SOMERSON
@ECHO OFF
IF !%1==! GOTO VIEWDATA
REM IF NO COMMAND-LINE ARG...
FIND "%1" C:\BOZO\BOOKLIST.TXT
GOTO EXIT0
REM PRINT LINE WITH STRING MATCH, THEN EXIT.
:VIEWDATA
TYPE C:\BOZO\BOOKLIST.TXT | MORE
REM SHOW ENTIRE FILE, 1 PAGE AT A TIME.
:EXIT0
#!/bin/bash
# viewdata.sh
# Conversion of VIEWDATA.BAT to shell script.
DATAFILE=/home/bozo/datafiles/book-collection.data
ARGNO=1
# @ECHO OFF Command unnecessary here.
if [ $# -lt "$ARGNO" ] # IF !%1==! GOTO VIEWDATA
then
less $DATAFILE # TYPE C:\MYDIR\BOOKLIST.TXT | MORE
else
grep "$1" $DATAFILE # FIND "%1" C:\MYDIR\BOOKLIST.TXT
fi
exit 0 # :EXIT0
# GOTOs, labels, smoke-and-mirrors, and flimflam unnecessary.
# The converted script is short, sweet, and clean,
#+ which is more than can be said for the original.</pre>]
#!/bin/bash
# fibo.sh : Fibonacci sequence (recursive)
# Author: M. Cooper
# License: GPL3
# ----------algorithm--------------
# Fibo(0) = 0
# Fibo(1) = 1
# else
# Fibo(j) = Fibo(j-1) + Fibo(j-2)
# ---------------------------------
MAXTERM=15 # Number of terms (+1) to generate.
MINIDX=2 # If idx is less than 2, then Fibo(idx) = idx.
Fibonacci ()
{
idx=$1 # Doesn't need to be local. Why not?
if [ "$idx" -lt "$MINIDX" ]
then
echo "$idx" # First two terms are 0 1 ... see above.
else
(( --idx )) # j-1
term1=$( Fibonacci $idx ) # Fibo(j-1)
(( --idx )) # j-2
term2=$( Fibonacci $idx ) # Fibo(j-2)
echo $(( term1 + term2 ))
fi
# An ugly, ugly kludge.
# The more elegant implementation of recursive fibo in C
#+ is a straightforward translation of the algorithm in lines 7 - 10.
}
for i in $(seq 0 $MAXTERM)
do # Calculate $MAXTERM+1 terms.
FIBO=$(Fibonacci $i)
echo -n "$FIBO "
done
# 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610
# Takes a while, doesn't it? Recursion in a script is slow.
echo
exit 0
#! /bin/bash
#
# The Towers Of Hanoi
# Bash script
# Copyright (C) 2000 Amit Singh. All Rights Reserved.
# http://hanoi.kernelthread.com
#
# Tested under Bash version 2.05b.0(13)-release.
# Also works under Bash version 3.x.
#
# Used in "Advanced Bash Scripting Guide"
#+ with permission of script author.
# Slightly modified and commented by ABS author.
#=================================================================#
# The Tower of Hanoi is a mathematical puzzle attributed to
#+ Edouard Lucas, a nineteenth-century French mathematician.
#
# There are three vertical posts set in a base.
# The first post has a set of annular rings stacked on it.
# These rings are disks with a hole drilled out of the center,
#+ so they can slip over the posts and rest flat.
# The rings have different diameters, and they stack in ascending
#+ order, according to size.
# The smallest ring is on top, and the largest on the bottom.
#
# The task is to transfer the stack of rings
#+ to one of the other posts.
# You can move only one ring at a time to another post.
# You are permitted to move rings back to the original post.
# You may place a smaller ring atop a larger one,
#+ but *not* vice versa.
# Again, it is forbidden to place a larger ring atop a smaller one.
#
# For a small number of rings, only a few moves are required.
#+ For each additional ring,
#+ the required number of moves approximately doubles,
#+ and the "strategy" becomes increasingly complicated.
#
# For more information, see http://hanoi.kernelthread.com
#+ or pp. 186-92 of _The Armchair Universe_ by A.K. Dewdney.
#
#
# ... ... ...
# | | | | | |
# _|_|_ | | | |
# |_____| | | | |
# |_______| | | | |
# |_________| | | | |
# |___________| | | | |
# | | | | | |
# .--------------------------------------------------------------.
# |**************************************************************|
# #1 #2 #3
#
#=================================================================#
E_NOPARAM=66 # No parameter passed to script.
E_BADPARAM=67 # Illegal number of disks passed to script.
Moves= # Global variable holding number of moves.
# Modification to original script.
dohanoi() { # Recursive function.
case $1 in
0)
;;
*)
dohanoi "$(($1-1))" $2 $4 $3
echo move $2 "--&gt;" $3
((Moves++)) # Modification to original script.
dohanoi "$(($1-1))" $4 $3 $2
;;
esac
}
case $# in
1) case $(($1&gt;0)) in # Must have at least one disk.
1) # Nested case statement.
dohanoi $1 1 3 2
echo "Total moves = $Moves" # 2^n - 1, where n = # of disks.
exit 0;
;;
*)
echo "$0: illegal value for number of disks";
exit $E_BADPARAM;
;;
esac
;;
*)
echo "usage: $0 N"
echo " Where \"N\" is the number of disks."
exit $E_NOPARAM;
;;
esac
# Exercises:
# ---------
# 1) Would commands beyond this point ever be executed?
# Why not? (Easy)
# 2) Explain the workings of the workings of the "dohanoi" function.
# (Difficult -- see the Dewdney reference, above.)</pre>]
#!/bin/bash
# mail-format.sh (ver. 1.1): Format e-mail messages.
# Gets rid of carets, tabs, and also folds excessively long lines.
# =================================================================
# Standard Check for Script Argument(s)
ARGS=1
E_BADARGS=85
E_NOFILE=86
if [ $# -ne $ARGS ] # Correct number of arguments passed to script?
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS
fi
if [ -f "$1" ] # Check if file exists.
then
file_name=$1
else
echo "File \"$1\" does not exist."
exit $E_NOFILE
fi
# -----------------------------------------------------------------
MAXWIDTH=70 # Width to fold excessively long lines to.
# =================================
# A variable can hold a sed script.
# It's a useful technique.
sedscript='s/^&gt;//
s/^ *&gt;//
s/^ *//
s/ *//'
# =================================
# Delete carets and tabs at beginning of lines,
#+ then fold lines to $MAXWIDTH characters.
sed "$sedscript" $1 | fold -s --width=$MAXWIDTH
# -s option to "fold"
#+ breaks lines at whitespace, if possible.
# This script was inspired by an article in a well-known trade journal
#+ extolling a 164K MS Windows utility with similar functionality.
#
# An nice set of text processing utilities and an efficient
#+ scripting language provide an alternative to the bloated executables
#+ of a clunky operating system.
exit $?
#! /bin/bash
# rn.sh
# Very simpleminded filename "rename" utility (based on "lowercase.sh").
#
# The "ren" utility, by Vladimir Lanin (lanin@csd2.nyu.edu),
#+ does a much better job of this.
ARGS=2
E_BADARGS=85
ONE=1 # For getting singular/plural right (see below).
if [ $# -ne "$ARGS" ]
then
echo "Usage: `basename $0` old-pattern new-pattern"
# As in "rn gif jpg", which renames all gif files in working directory to jpg.
exit $E_BADARGS
fi
number=0 # Keeps track of how many files actually renamed.
for filename in *$1* #Traverse all matching files in directory.
do
if [ -f "$filename" ] # If finds match...
then
fname=`basename $filename` # Strip off path.
n=`echo $fname | sed -e "s/$1/$2/"` # Substitute new for old in filename.
mv $fname $n # Rename.
let "number += 1"
fi
done
if [ "$number" -eq "$ONE" ] # For correct grammar.
then
echo "$number file renamed."
else
echo "$number files renamed."
fi
exit $?
# Exercises:
# ---------
# What types of files will this not work on?
# How can this be fixed?
#! /bin/bash
# blank-rename.sh
#
# Substitutes underscores for blanks in all the filenames in a directory.
ONE=1 # For getting singular/plural right (see below).
number=0 # Keeps track of how many files actually renamed.
FOUND=0 # Successful return value.
for filename in * #Traverse all files in directory.
do
echo "$filename" | grep -q " " # Check whether filename
if [ $? -eq $FOUND ] #+ contains space(s).
then
fname=$filename # Yes, this filename needs work.
n=`echo $fname | sed -e "s/ /_/g"` # Substitute underscore for blank.
mv "$fname" "$n" # Do the actual renaming.
let "number += 1"
fi
done
if [ "$number" -eq "$ONE" ] # For correct grammar.
then
echo "$number file renamed."
else
echo "$number files renamed."
fi
exit 0
#!/bin/bash
# Example "ex72.sh" modified to use encrypted password.
# Note that this is still rather insecure,
#+ since the decrypted password is sent in the clear.
# Use something like "ssh" if this is a concern.
E_BADARGS=85
if [ -z "$1" ]
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS
fi
Username=bozo # Change to suit.
pword=/home/bozo/secret/password_encrypted.file
# File containing encrypted password.
Filename=`basename $1` # Strips pathname out of file name.
Server="XXX"
Directory="YYY" # Change above to actual server name & directory.
Password=`cruft <$pword` # Decrypt password.
# Uses the author's own "cruft" file encryption package,
#+ based on the classic "onetime pad" algorithm,
#+ and obtainable from:
#+ Primary-site: ftp://ibiblio.org/pub/Linux/utils/file
#+ cruft-0.2.tar.gz [16k]
ftp -n $Server <<End-Of-Session
user $Username $Password
binary
bell
cd $Directory
put $Filename
bye
End-Of-Session
# -n option to "ftp" disables auto-logon.
# Note that "bell" rings 'bell' after each file transfer.
exit 0
#!/bin/bash
# copy-cd.sh: copying a data CD
CDROM=/dev/cdrom # CD ROM device
OF=/home/bozo/projects/cdimage.iso # output file
# /xxxx/xxxxxxxx/ Change to suit your system.
BLOCKSIZE=2048
# SPEED=10 # If unspecified, uses max spd.
# DEVICE=/dev/cdrom older version.
DEVICE="1,0,0"
echo; echo "Insert source CD, but do *not* mount it."
echo "Press ENTER when ready. "
read ready # Wait for input, $ready not used.
echo; echo "Copying the source CD to $OF."
echo "This may take a while. Please be patient."
dd if=$CDROM of=$OF bs=$BLOCKSIZE # Raw device copy.
echo; echo "Remove data CD."
echo "Insert blank CDR."
echo "Press ENTER when ready. "
read ready # Wait for input, $ready not used.
echo "Copying $OF to CDR."
# cdrecord -v -isosize speed=$SPEED dev=$DEVICE $OF # Old version.
wodim -v -isosize dev=$DEVICE $OF
# Uses Joerg Schilling's "cdrecord" package (see its docs).
# http://www.fokus.gmd.de/nthp/employees/schilling/cdrecord.html
# Newer Linux distros may use "wodim" rather than "cdrecord" ...
echo; echo "Done copying $OF to CDR on device $CDROM."
echo "Do you want to erase the image file (y/n)? " # Probably a huge file.
read answer
case "$answer" in
[yY]) rm -f $OF
echo "$OF erased."
;;
*) echo "$OF not erased.";;
esac
echo
# Exercise:
# Change the above "case" statement to also accept "yes" and "Yes" as input.
exit 0
#!/bin/bash
# collatz.sh
# The notorious "hailstone" or Collatz series.
# -------------------------------------------
# 1) Get the integer "seed" from the command-line.
# 2) NUMBER <-- seed
# 3) Print NUMBER.
# 4) If NUMBER is even, divide by 2, or
# 5)+ if odd, multiply by 3 and add 1.
# 6) NUMBER <-- result
# 7) Loop back to step 3 (for specified number of iterations).
#
# The theory is that every such sequence,
#+ no matter how large the initial value,
#+ eventually settles down to repeating "4,2,1..." cycles,
#+ even after fluctuating through a wide range of values.
#
# This is an instance of an "iterate,"
#+ an operation that feeds its output back into its input.
# Sometimes the result is a "chaotic" series.
MAX_ITERATIONS=200
# For large seed numbers (&gt;32000), try increasing MAX_ITERATIONS.
h=${1:-$$} # Seed.
# Use $PID as seed,
#+ if not specified as command-line arg.
echo
echo "C($h) -*- $MAX_ITERATIONS Iterations"
echo
for ((i=1; i<=MAX_ITERATIONS; i++))
do
# echo -n "$h "
# ^^^
# tab
# printf does it better ...
COLWIDTH=%7d
printf $COLWIDTH $h
let "remainder = h % 2"
if [ "$remainder" -eq 0 ] # Even?
then
let "h /= 2" # Divide by 2.
else
let "h = h*3 + 1" # Multiply by 3 and add 1.
fi
COLUMNS=10 # Output 10 values per line.
let "line_break = i % $COLUMNS"
if [ "$line_break" -eq 0 ]
then
echo
fi
done
echo
# For more information on this strange mathematical function,
#+ see _Computers, Pattern, Chaos, and Beauty_, by Pickover, p. 185 ff.,
#+ as listed in the bibliography.
exit 0
#!/bin/bash
# days-between.sh: Number of days between two dates.
# Usage: ./days-between.sh [M]M/[D]D/YYYY [M]M/[D]D/YYYY
#
# Note: Script modified to account for changes in Bash, v. 2.05b +,
#+ that closed the loophole permitting large negative
#+ integer return values.
ARGS=2 # Two command-line parameters expected.
E_PARAM_ERR=85 # Param error.
REFYR=1600 # Reference year.
CENTURY=100
DIY=365
ADJ_DIY=367 # Adjusted for leap year + fraction.
MIY=12
DIM=31
LEAPCYCLE=4
MAXRETVAL=255 # Largest permissible
#+ positive return value from a function.
diff= # Declare global variable for date difference.
value= # Declare global variable for absolute value.
day= # Declare globals for day, month, year.
month=
year=
Param_Error () # Command-line parameters wrong.
{
echo "Usage: `basename $0` [M]M/[D]D/YYYY [M]M/[D]D/YYYY"
echo " (date must be after 1/3/1600)"
exit $E_PARAM_ERR
}
Parse_Date () # Parse date from command-line params.
{
month=${1%%/**}
dm=${1%/**} # Day and month.
day=${dm#*/}
let "year = `basename $1`" # Not a filename, but works just the same.
}
check_date () # Checks for invalid date(s) passed.
{
[ "$day" -gt "$DIM" ] || [ "$month" -gt "$MIY" ] ||
[ "$year" -lt "$REFYR" ] && Param_Error
# Exit script on bad value(s).
# Uses or-list / and-list.
#
# Exercise: Implement more rigorous date checking.
}
strip_leading_zero () # Better to strip possible leading zero(s)
{ #+ from day and/or month
return ${1#0} #+ since otherwise Bash will interpret them
} #+ as octal values (POSIX.2, sect 2.9.2.1).
day_index () # Gauss' Formula:
{ # Days from March 1, 1600 to date passed as param.
# ^^^^^^^^^^^^^
day=$1
month=$2
year=$3
let "month = $month - 2"
if [ "$month" -le 0 ]
then
let "month += 12"
let "year -= 1"
fi
let "year -= $REFYR"
let "indexyr = $year / $CENTURY"
let "Days = $DIY*$year + $year/$LEAPCYCLE - $indexyr \
+ $indexyr/$LEAPCYCLE + $ADJ_DIY*$month/$MIY + $day - $DIM"
# For an in-depth explanation of this algorithm, see
#+ http://weblogs.asp.net/pgreborio/archive/2005/01/06/347968.aspx
echo $Days
}
calculate_difference () # Difference between two day indices.
{
let "diff = $1 - $2" # Global variable.
}
abs () # Absolute value
{ # Uses global "value" variable.
if [ "$1" -lt 0 ] # If negative
then #+ then
let "value = 0 - $1" #+ change sign,
else #+ else
let "value = $1" #+ leave it alone.
fi
}
if [ $# -ne "$ARGS" ] # Require two command-line params.
then
Param_Error
fi
Parse_Date $1
check_date $day $month $year # See if valid date.
strip_leading_zero $day # Remove any leading zeroes
day=$? #+ on day and/or month.
strip_leading_zero $month
month=$?
let "date1 = `day_index $day $month $year`"
Parse_Date $2
check_date $day $month $year
strip_leading_zero $day
day=$?
strip_leading_zero $month
month=$?
date2=$(day_index $day $month $year) # Command substitution.
calculate_difference $date1 $date2
abs $diff # Make sure it's positive.
diff=$value
echo $diff
exit 0
# Exercise:
# --------
# If given only one command-line parameter, have the script
#+ use today's date as the second.
# Compare this script with
#+ the implementation of Gauss' Formula in a C program at
#+ http://buschencrew.hypermart.net/software/datedif
#!/bin/bash
# makedict.sh [make dictionary]
# Modification of /usr/sbin/mkdict (/usr/sbin/cracklib-forman) script.
# Original script copyright 1993, by Alec Muffett.
#
# This modified script included in this document in a manner
#+ consistent with the "LICENSE" document of the "Crack" package
#+ that the original script is a part of.
# This script processes text files to produce a sorted list
#+ of words found in the files.
# This may be useful for compiling dictionaries
#+ and for other lexicographic purposes.
E_BADARGS=85
if [ ! -r "$1" ] # Need at least one
then #+ valid file argument.
echo "Usage: $0 files-to-process"
exit $E_BADARGS
fi
# SORT="sort" # No longer necessary to define
#+ options to sort. Changed from
#+ original script.
cat $* | # Dump specified files to stdout.
tr A-Z a-z | # Convert to lowercase.
tr ' ' '\012' | # New: change spaces to newlines.
# tr -cd '\012[a-z][0-9]' | # Get rid of everything
#+ non-alphanumeric (in orig. script).
tr -c '\012a-z' '\012' | # Rather than deleting non-alpha
#+ chars, change them to newlines.
sort | # $SORT options unnecessary now.
uniq | # Remove duplicates.
grep -v '^#' | # Delete lines starting with #.
grep -v '^$' # Delete blank lines.
exit $?
#!/bin/bash
# soundex.sh: Calculate "soundex" code for names
# =======================================================
# Soundex script
# by
# Mendel Cooper
# thegrendel.abs@gmail.com
# reldate: 23 January, 2002
#
# Placed in the Public Domain.
#
# A slightly different version of this script appeared in
#+ Ed Schaefer's July, 2002 "Shell Corner" column
#+ in "Unix Review" on-line,
#+ http://www.unixreview.com/documents/uni1026336632258/
# =======================================================
ARGCOUNT=1 # Need name as argument.
E_WRONGARGS=90
if [ $# -ne "$ARGCOUNT" ]
then
echo "Usage: `basename $0` name"
exit $E_WRONGARGS
fi
assign_value () # Assigns numerical value
{ #+ to letters of name.
val1=bfpv # 'b,f,p,v' = 1
val2=cgjkqsxz # 'c,g,j,k,q,s,x,z' = 2
val3=dt # etc.
val4=l
val5=mn
val6=r
# Exceptionally clever use of 'tr' follows.
# Try to figure out what is going on here.
value=$( echo "$1" \
| tr -d wh \
| tr $val1 1 | tr $val2 2 | tr $val3 3 \
| tr $val4 4 | tr $val5 5 | tr $val6 6 \
| tr -s 123456 \
| tr -d aeiouy )
# Assign letter values.
# Remove duplicate numbers, except when separated by vowels.
# Ignore vowels, except as separators, so delete them last.
# Ignore 'w' and 'h', even as separators, so delete them first.
#
# The above command substitution lays more pipe than a plumber <g&gt;.
}
input_name="$1"
echo
echo "Name = $input_name"
# Change all characters of name input to lowercase.
# ------------------------------------------------
name=$( echo $input_name | tr A-Z a-z )
# ------------------------------------------------
# Just in case argument to script is mixed case.
# Prefix of soundex code: first letter of name.
# --------------------------------------------
char_pos=0 # Initialize character position.
prefix0=${name:$char_pos:1}
prefix=`echo $prefix0 | tr a-z A-Z`
# Uppercase 1st letter of soundex.
let "char_pos += 1" # Bump character position to 2nd letter of name.
name1=${name:$char_pos}
# ++++++++++++++++++++++++++ Exception Patch ++++++++++++++++++++++++++++++
# Now, we run both the input name and the name shifted one char
#+ to the right through the value-assigning function.
# If we get the same value out, that means that the first two characters
#+ of the name have the same value assigned, and that one should cancel.
# However, we also need to test whether the first letter of the name
#+ is a vowel or 'w' or 'h', because otherwise this would bollix things up.
char1=`echo $prefix | tr A-Z a-z` # First letter of name, lowercased.
assign_value $name
s1=$value
assign_value $name1
s2=$value
assign_value $char1
s3=$value
s3=9$s3 # If first letter of name is a vowel
#+ or 'w' or 'h',
#+ then its "value" will be null (unset).
#+ Therefore, set it to 9, an otherwise
#+ unused value, which can be tested for.
if [[ "$s1" -ne "$s2" || "$s3" -eq 9 ]]
then
suffix=$s2
else
suffix=${s2:$char_pos}
fi
# ++++++++++++++++++++++ end Exception Patch ++++++++++++++++++++++++++++++
padding=000 # Use at most 3 zeroes to pad.
soun=$prefix$suffix$padding # Pad with zeroes.
MAXLEN=4 # Truncate to maximum of 4 chars.
soundex=${soun:0:$MAXLEN}
echo "Soundex = $soundex"
echo
# The soundex code is a method of indexing and classifying names
#+ by grouping together the ones that sound alike.
# The soundex code for a given name is the first letter of the name,
#+ followed by a calculated three-number code.
# Similar sounding names should have almost the same soundex codes.
# Examples:
# Smith and Smythe both have a "S-530" soundex.
# Harrison = H-625
# Hargison = H-622
# Harriman = H-655
# This works out fairly well in practice, but there are numerous anomalies.
#
#
# The U.S. Census and certain other governmental agencies use soundex,
# as do genealogical researchers.
#
# For more information,
#+ see the "National Archives and Records Administration home page",
#+ http://www.nara.gov/genealogy/soundex/soundex.html
# Exercise:
# --------
# Simplify the "Exception Patch" section of this script.
exit 0
#!/bin/bash
# life.sh: "Life in the Slow Lane"
# Author: Mendel Cooper
# License: GPL3
# Version 0.2: Patched by Daniel Albers
#+ to allow non-square grids as input.
# Version 0.2.1: Added 2-second delay between generations.
# ##################################################################### #
# This is the Bash script version of John Conway's "Game of Life". #
# "Life" is a simple implementation of cellular automata. #
# --------------------------------------------------------------------- #
# On a rectangular grid, let each "cell" be either "living" or "dead." #
# Designate a living cell with a dot, and a dead one with a blank space.#
# Begin with an arbitrarily drawn dot-and-blank grid, #
#+ and let this be the starting generation: generation 0. #
# Determine each successive generation by the following rules: #
# 1) Each cell has 8 neighbors, the adjoining cells #
#+ left, right, top, bottom, and the 4 diagonals. #
# #
# 123 #
# 4*5 The * is the cell under consideration. #
# 678 #
# #
# 2) A living cell with either 2 or 3 living neighbors remains alive. #
SURVIVE=2 #
# 3) A dead cell with 3 living neighbors comes alive, a "birth." #
BIRTH=3 #
# 4) All other cases result in a dead cell for the next generation. #
# ##################################################################### #
startfile=gen0 # Read the starting generation from the file "gen0" ...
# Default, if no other file specified when invoking script.
#
if [ -n "$1" ] # Specify another "generation 0" file.
then
startfile="$1"
fi
############################################
# Abort script if "startfile" not specified
#+ and
#+ default file "gen0" not present.
E_NOSTARTFILE=86
if [ ! -e "$startfile" ]
then
echo "Startfile \""$startfile"\" missing!"
exit $E_NOSTARTFILE
fi
############################################
ALIVE1=.
DEAD1=_
# Represent living and dead cells in the start-up file.
# -----------------------------------------------------#
# This script uses a 10 x 10 grid (may be increased,
#+ but a large grid will slow down execution).
ROWS=10
COLS=10
# Change above two variables to match desired grid size.
# -----------------------------------------------------#
GENERATIONS=10 # How many generations to cycle through.
# Adjust this upwards
#+ if you have time on your hands.
NONE_ALIVE=85 # Exit status on premature bailout,
#+ if no cells left alive.
DELAY=2 # Pause between generations.
TRUE=0
FALSE=1
ALIVE=0
DEAD=1
avar= # Global; holds current generation.
generation=0 # Initialize generation count.
# =================================================================
let "cells = $ROWS * $COLS" # How many cells.
# Arrays containing "cells."
declare -a initial
declare -a current
display ()
{
alive=0 # How many cells alive at any given time.
# Initially zero.
declare -a arr
arr=( `echo "$1"` ) # Convert passed arg to array.
element_count=${#arr[*]}
local i
local rowcheck
for ((i=0; i<$element_count; i++))
do
# Insert newline at end of each row.
let "rowcheck = $i % COLS"
if [ "$rowcheck" -eq 0 ]
then
echo # Newline.
echo -n " " # Indent.
fi
cell=${arr[i]}
if [ "$cell" = . ]
then
let "alive += 1"
fi
echo -n "$cell" | sed -e 's/_/ /g'
# Print out array, changing underscores to spaces.
done
return
}
IsValid () # Test if cell coordinate valid.
{
if [ -z "$1" -o -z "$2" ] # Mandatory arguments missing?
then
return $FALSE
fi
local row
local lower_limit=0 # Disallow negative coordinate.
local upper_limit
local left
local right
let "upper_limit = $ROWS * $COLS - 1" # Total number of cells.
if [ "$1" -lt "$lower_limit" -o "$1" -gt "$upper_limit" ]
then
return $FALSE # Out of array bounds.
fi
row=$2
let "left = $row * $COLS" # Left limit.
let "right = $left + $COLS - 1" # Right limit.
if [ "$1" -lt "$left" -o "$1" -gt "$right" ]
then
return $FALSE # Beyond row boundary.
fi
return $TRUE # Valid coordinate.
}
IsAlive () # Test whether cell is alive.
# Takes array, cell number, and
{ #+ state of cell as arguments.
GetCount "$1" $2 # Get alive cell count in neighborhood.
local nhbd=$?
if [ "$nhbd" -eq "$BIRTH" ] # Alive in any case.
then
return $ALIVE
fi
if [ "$3" = "." -a "$nhbd" -eq "$SURVIVE" ]
then # Alive only if previously alive.
return $ALIVE
fi
return $DEAD # Defaults to dead.
}
GetCount () # Count live cells in passed cell's neighborhood.
# Two arguments needed:
# $1) variable holding array
# $2) cell number
{
local cell_number=$2
local array
local top
local center
local bottom
local r
local row
local i
local t_top
local t_cen
local t_bot
local count=0
local ROW_NHBD=3
array=( `echo "$1"` )
let "top = $cell_number - $COLS - 1" # Set up cell neighborhood.
let "center = $cell_number - 1"
let "bottom = $cell_number + $COLS - 1"
let "r = $cell_number / $COLS"
for ((i=0; i<$ROW_NHBD; i++)) # Traverse from left to right.
do
let "t_top = $top + $i"
let "t_cen = $center + $i"
let "t_bot = $bottom + $i"
let "row = $r" # Count center row.
IsValid $t_cen $row # Valid cell position?
if [ $? -eq "$TRUE" ]
then
if [ ${array[$t_cen]} = "$ALIVE1" ] # Is it alive?
then # If yes, then ...
let "count += 1" # Increment count.
fi
fi
let "row = $r - 1" # Count top row.
IsValid $t_top $row
if [ $? -eq "$TRUE" ]
then
if [ ${array[$t_top]} = "$ALIVE1" ] # Redundancy here.
then # Can it be optimized?
let "count += 1"
fi
fi
let "row = $r + 1" # Count bottom row.
IsValid $t_bot $row
if [ $? -eq "$TRUE" ]
then
if [ ${array[$t_bot]} = "$ALIVE1" ]
then
let "count += 1"
fi
fi
done
if [ ${array[$cell_number]} = "$ALIVE1" ]
then
let "count -= 1" # Make sure value of tested cell itself
fi #+ is not counted.
return $count
}
next_gen () # Update generation array.
{
local array
local i=0
array=( `echo "$1"` ) # Convert passed arg to array.
while [ "$i" -lt "$cells" ]
do
IsAlive "$1" $i ${array[$i]} # Is the cell alive?
if [ $? -eq "$ALIVE" ]
then # If alive, then
array[$i]=. #+ represent the cell as a period.
else
array[$i]="_" # Otherwise underscore
fi #+ (will later be converted to space).
let "i += 1"
done
# let "generation += 1" # Increment generation count.
### Why was the above line commented out?
# Set variable to pass as parameter to "display" function.
avar=`echo ${array[@]}` # Convert array back to string variable.
display "$avar" # Display it.
echo; echo
echo "Generation $generation - $alive alive"
if [ "$alive" -eq 0 ]
then
echo
echo "Premature exit: no more cells alive!"
exit $NONE_ALIVE # No point in continuing
fi #+ if no live cells.
}
# =========================================================
# main ()
# {
# Load initial array with contents of startup file.
initial=( `cat "$startfile" | sed -e '/#/d' | tr -d '\n' |\
# Delete lines containing '#' comment character.
sed -e 's/\./\. /g' -e 's/_/_ /g'` )
# Remove linefeeds and insert space between elements.
clear # Clear screen.
echo # Title
setterm -reverse on
echo "======================="
setterm -reverse off
echo " $GENERATIONS generations"
echo " of"
echo "\"Life in the Slow Lane\""
setterm -reverse on
echo "======================="
setterm -reverse off
sleep $DELAY # Display "splash screen" for 2 seconds.
# -------- Display first generation. --------
Gen0=`echo ${initial[@]}`
display "$Gen0" # Display only.
echo; echo
echo "Generation $generation - $alive alive"
sleep $DELAY
# -------------------------------------------
let "generation += 1" # Bump generation count.
echo
# ------- Display second generation. -------
Cur=`echo ${initial[@]}`
next_gen "$Cur" # Update & display.
sleep $DELAY
# ------------------------------------------
let "generation += 1" # Increment generation count.
# ------ Main loop for displaying subsequent generations ------
while [ "$generation" -le "$GENERATIONS" ]
do
Cur="$avar"
next_gen "$Cur"
let "generation += 1"
sleep $DELAY
done
# ==============================================================
echo
# }
exit 0 # CEOF:EOF
# The grid in this script has a "boundary problem."
# The the top, bottom, and sides border on a void of dead cells.
# Exercise: Change the script to have the grid wrap around,
# + so that the left and right sides will "touch,"
# + as will the top and bottom.
#
# Exercise: Create a new "gen0" file to seed this script.
# Use a 12 x 16 grid, instead of the original 10 x 10 one.
# Make the necessary changes to the script,
#+ so it will run with the altered file.
#
# Exercise: Modify this script so that it can determine the grid size
#+ from the "gen0" file, and set any variables necessary
#+ for the script to run.
# This would make unnecessary any changes to variables
#+ in the script for an altered grid size.
#
# Exercise: Optimize this script.
# It has redundant code.
# gen0
#
# This is an example "generation 0" start-up file for "life.sh".
# --------------------------------------------------------------
# The "gen0" file is a 10 x 10 grid using a period (.) for live cells,
#+ and an underscore (_) for dead ones. We cannot simply use spaces
#+ for dead cells in this file because of a peculiarity in Bash arrays.
# [Exercise for the reader: explain this.]
#
# Lines beginning with a '#' are comments, and the script ignores them.
__.__..___
__.._.____
____.___..
_._______.
____._____
..__...___
____._____
___...____
__.._..___
_..___..__
#! /bin/sh
# Strips off the header from a mail/News message i.e. till the first
#+ empty line.
# Author: Mark Moraes, University of Toronto
# ==&gt; These comments added by author of this document.
if [ $# -eq 0 ]; then
# ==&gt; If no command-line args present, then works on file redirected to stdin.
sed -e '1,/^$/d' -e '/^[ ]*$/d'
# --&gt; Delete empty lines and all lines until
# --&gt; first one beginning with white space.
else
# ==&gt; If command-line args present, then work on files named.
for i do
sed -e '1,/^$/d' -e '/^[ ]*$/d' $i
# --&gt; Ditto, as above.
done
fi
exit
# ==&gt; Exercise: Add error checking and other options.
# ==&gt;
# ==&gt; Note that the small sed script repeats, except for the arg passed.
# ==&gt; Does it make sense to embed it in a function? Why or why not?
/*
* Copyright University of Toronto 1988, 1989.
* Written by Mark Moraes
*
* Permission is granted to anyone to use this software for any purpose on
* any computer system, and to alter it and redistribute it freely, subject
* to the following restrictions:
*
* 1. The author and the University of Toronto are not responsible
* for the consequences of use of this software, no matter how awful,
* even if they arise from flaws in it.
*
* 2. The origin of this software must not be misrepresented, either by
* explicit claim or by omission. Since few users ever read sources,
* credits must appear in the documentation.
*
* 3. Altered versions must be plainly marked as such, and must not be
* misrepresented as being the original software. Since few users
* ever read sources, credits must appear in the documentation.
*
* 4. This notice may not be removed or altered.
*/
#!/bin/bash
#
#
# Random password generator for Bash 2.x +
#+ by Antek Sawicki <tenox@tenox.tc&gt;,
#+ who generously gave usage permission to the ABS Guide author.
#
# ==&gt; Comments added by document author ==&gt;
MATRIX="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
# ==&gt; Password will consist of alphanumeric characters.
LENGTH="8"
# ==&gt; May change 'LENGTH' for longer password.
while [ "${n:=1}" -le "$LENGTH" ]
# ==&gt; Recall that := is "default substitution" operator.
# ==&gt; So, if 'n' has not been initialized, set it to 1.
do
PASS="$PASS${MATRIX:$(($RANDOM%${#MATRIX})):1}"
# ==&gt; Very clever, but tricky.
# ==&gt; Starting from the innermost nesting...
# ==&gt; ${#MATRIX} returns length of array MATRIX.
# ==&gt; $RANDOM%${#MATRIX} returns random number between 1
# ==&gt; and [length of MATRIX] - 1.
# ==&gt; ${MATRIX:$(($RANDOM%${#MATRIX})):1}
# ==&gt; returns expansion of MATRIX at random position, by length 1.
# ==&gt; See {var:pos:len} parameter substitution in Chapter 9.
# ==&gt; and the associated examples.
# ==&gt; PASS=... simply pastes this result onto previous PASS (concatenation).
# ==&gt; To visualize this more clearly, uncomment the following line
# echo "$PASS"
# ==&gt; to see PASS being built up,
# ==&gt; one character at a time, each iteration of the loop.
let n+=1
# ==&gt; Increment 'n' for next pass.
done
echo "$PASS" # ==&gt; Or, redirect to a file, as desired.
exit 0
#!/bin/bash
# ==&gt; Script by James R. Van Zandt, and used here with his permission.
# ==&gt; Comments added by author of this document.
HERE=`uname -n` # ==&gt; hostname
THERE=bilbo
echo "starting remote backup to $THERE at `date +%r`"
# ==&gt; `date +%r` returns time in 12-hour format, i.e. "08:08:34 PM".
# make sure /pipe really is a pipe and not a plain file
rm -rf /pipe
mkfifo /pipe # ==&gt; Create a "named pipe", named "/pipe" ...
# ==&gt; 'su xyz' runs commands as user "xyz".
# ==&gt; 'ssh' invokes secure shell (remote login client).
su xyz -c "ssh $THERE \"cat &gt; /home/xyz/backup/${HERE}-daily.tar.gz\" < /pipe"&
cd /
tar -czf - bin boot dev etc home info lib man root sbin share usr var &gt; /pipe
# ==&gt; Uses named pipe, /pipe, to communicate between processes:
# ==&gt; 'tar/gzip' writes to /pipe and 'ssh' reads from /pipe.
# ==&gt; The end result is this backs up the main directories, from / on down.
# ==&gt; What are the advantages of a "named pipe" in this situation,
# ==&gt;+ as opposed to an "anonymous pipe", with |?
# ==&gt; Will an anonymous pipe even work here?
# ==&gt; Is it necessary to delete the pipe before exiting the script?
# ==&gt; How could that be done?
exit 0
#!/bin/bash
# primes.sh: Generate prime numbers, without using arrays.
# Script contributed by Stephane Chazelas.
# This does *not* use the classic "Sieve of Eratosthenes" algorithm,
#+ but instead the more intuitive method of testing each candidate number
#+ for factors (divisors), using the "%" modulo operator.
LIMIT=1000 # Primes, 2 ... 1000.
Primes()
{
(( n = $1 + 1 )) # Bump to next integer.
shift # Next parameter in list.
# echo "_n=$n i=$i_"
if (( n == LIMIT ))
then echo $*
return
fi
for i; do # "i" set to "@", previous values of $n.
# echo "-n=$n i=$i-"
(( i * i &gt; n )) && break # Optimization.
(( n % i )) && continue # Sift out non-primes using modulo operator.
Primes $n $@ # Recursion inside loop.
return
done
Primes $n $@ $n # Recursion outside loop.
# Successively accumulate
#+ positional parameters.
# "$@" is the accumulating list of primes.
}
Primes 1
exit $?
# Pipe output of the script to 'fmt' for prettier printing.
# Uncomment lines 16 and 24 to help figure out what is going on.
# Compare the speed of this algorithm for generating primes
#+ with the Sieve of Eratosthenes (ex68.sh).
# Exercise: Rewrite this script without recursion.
#!/bin/bash
# tree.sh
# Written by Rick Boivie.
# Used with permission.
# This is a revised and simplified version of a script
#+ by Jordi Sanfeliu (the original author), and patched by Ian Kjos.
# This script replaces the earlier version used in
#+ previous releases of the Advanced Bash Scripting Guide.
# Copyright (c) 2002, by Jordi Sanfeliu, Rick Boivie, and Ian Kjos.
# ==&gt; Comments added by the author of this document.
search () {
for dir in `echo *`
# ==&gt; `echo *` lists all the files in current working directory,
#+ ==&gt; without line breaks.
# ==&gt; Similar effect to for dir in *
# ==&gt; but "dir in `echo *`" will not handle filenames with blanks.
do
if [ -d "$dir" ] ; then # ==&gt; If it is a directory (-d)...
zz=0 # ==&gt; Temp variable, keeping track of
# directory level.
while [ $zz != $1 ] # Keep track of inner nested loop.
do
echo -n "| " # ==&gt; Display vertical connector symbol,
# ==&gt; with 2 spaces & no line feed
# in order to indent.
zz=`expr $zz + 1` # ==&gt; Increment zz.
done
if [ -L "$dir" ] ; then # ==&gt; If directory is a symbolic link...
echo "+---$dir" `ls -l $dir | sed 's/^.*'$dir' //'`
# ==&gt; Display horiz. connector and list directory name, but...
# ==&gt; delete date/time part of long listing.
else
echo "+---$dir" # ==&gt; Display horizontal connector symbol...
# ==&gt; and print directory name.
numdirs=`expr $numdirs + 1` # ==&gt; Increment directory count.
if cd "$dir" ; then # ==&gt; If can move to subdirectory...
search `expr $1 + 1` # with recursion ;-)
# ==&gt; Function calls itself.
cd ..
fi
fi
fi
done
}
if [ $# != 0 ] ; then
cd $1 # Move to indicated directory.
#else # stay in current directory
fi
echo "Initial directory = `pwd`"
numdirs=0
search 0
echo "Total directories = $numdirs"
exit 0
#!/bin/bash
# tree2.sh
# Lightly modified/reformatted by ABS Guide author.
# Included in ABS Guide with permission of script author (thanks!).
## Recursive file/dirsize checking script, by Patsie
##
## This script builds a list of files/directories and their size (du -akx)
## and processes this list to a human readable tree shape
## The 'du -akx' is only as good as the permissions the owner has.
## So preferably run as root* to get the best results, or use only on
## directories for which you have read permissions. Anything you can't
## read is not in the list.
#* ABS Guide author advises caution when running scripts as root!
########## THIS IS CONFIGURABLE ##########
TOP=5 # Top 5 biggest (sub)directories.
MAXRECURS=5 # Max 5 subdirectories/recursions deep.
E_BL=80 # Blank line already returned.
E_DIR=81 # Directory not specified.
########## DON'T CHANGE ANYTHING BELOW THIS LINE ##########
PID=$$ # Our own process ID.
SELF=`basename $0` # Our own program name.
TMP="/tmp/${SELF}.${PID}.tmp" # Temporary 'du' result.
# Convert number to dotted thousand.
function dot { echo " $*" |
sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta' |
tail -c 12; }
# Usage: tree <recursion&gt; <indent prefix&gt; <min size&gt; <directory&gt;
function tree {
recurs="$1" # How deep nested are we?
prefix="$2" # What do we display before file/dirname?
minsize="$3" # What is the minumum file/dirsize?
dirname="$4" # Which directory are we checking?
# Get ($TOP) biggest subdirs/subfiles from TMP file.
LIST=`egrep "[[:space:]]${dirname}/[^/]*$" "$TMP" |
awk '{if($1&gt;'$minsize') print;}' | sort -nr | head -$TOP`
[ -z "$LIST" ] && return # Empty list, then go back.
cnt=0
num=`echo "$LIST" | wc -l` # How many entries in the list.
## Main loop
echo "$LIST" | while read size name; do
((cnt+=1)) # Count entry number.
bname=`basename "$name"` # We only need a basename of the entry.
[ -d "$name" ] && bname="$bname/"
# If it's a directory, append a slash.
echo "`dot $size`$prefix +-$bname"
# Display the result.
# Call ourself recursively if it's a directory
#+ and we're not nested too deep ($MAXRECURS).
# The recursion goes up: $((recurs+1))
# The prefix gets a space if it's the last entry,
#+ or a pipe if there are more entries.
# The minimum file/dirsize becomes
#+ a tenth of his parent: $((size/10)).
# Last argument is the full directory name to check.
if [ -d "$name" -a $recurs -lt $MAXRECURS ]; then
[ $cnt -lt $num ] \
|| (tree $((recurs+1)) "$prefix " $((size/10)) "$name") \
&& (tree $((recurs+1)) "$prefix |" $((size/10)) "$name")
fi
done
[ $? -eq 0 ] && echo " $prefix"
# Every time we jump back add a 'blank' line.
return $E_BL
# We return 80 to tell we added a blank line already.
}
### ###
### main program ###
### ###
rootdir="$@"
[ -d "$rootdir" ] ||
{ echo "$SELF: Usage: $SELF <directory&gt;" &gt;&2; exit $E_DIR; }
# We should be called with a directory name.
echo "Building inventory list, please wait ..."
# Show "please wait" message.
du -akx "$rootdir" 1&gt;"$TMP" 2&gt;/dev/null
# Build a temporary list of all files/dirs and their size.
size=`tail -1 "$TMP" | awk '{print $1}'`
# What is our rootdirectory's size?
echo "`dot $size` $rootdir"
# Display rootdirectory's entry.
tree 0 "" 0 "$rootdir"
# Display the tree below our rootdirectory.
rm "$TMP" 2&gt;/dev/null
# Clean up TMP file.
exit $?
#!/bin/bash
# string.bash --- bash emulation of string(3) library routines
# Author: Noah Friedman <friedman@prep.ai.mit.edu&gt;
# ==&gt; Used with his kind permission in this document.
# Created: 1992-07-01
# Last modified: 1993-09-29
# Public domain
# Conversion to bash v2 syntax done by Chet Ramey
# Commentary:
# Code:
#:docstring strcat:
# Usage: strcat s1 s2
#
# Strcat appends the value of variable s2 to variable s1.
#
# Example:
# a="foo"
# b="bar"
# strcat a b
# echo $a
# =&gt; foobar
#
#:end docstring:
###;;;autoload ==&gt; Autoloading of function commented out.
function strcat ()
{
local s1_val s2_val
s1_val=${!1} # indirect variable expansion
s2_val=${!2}
eval "$1"=\'"${s1_val}${s2_val}"\'
# ==&gt; eval $1='${s1_val}${s2_val}' avoids problems,
# ==&gt; if one of the variables contains a single quote.
}
#:docstring strncat:
# Usage: strncat s1 s2 $n
#
# Line strcat, but strncat appends a maximum of n characters from the value
# of variable s2. It copies fewer if the value of variabl s2 is shorter
# than n characters. Echoes result on stdout.
#
# Example:
# a=foo
# b=barbaz
# strncat a b 3
# echo $a
# =&gt; foobar
#
#:end docstring:
###;;;autoload
function strncat ()
{
local s1="$1"
local s2="$2"
local -i n="$3"
local s1_val s2_val
s1_val=${!s1} # ==&gt; indirect variable expansion
s2_val=${!s2}
if [ ${#s2_val} -gt ${n} ]; then
s2_val=${s2_val:0:$n} # ==&gt; substring extraction
fi
eval "$s1"=\'"${s1_val}${s2_val}"\'
# ==&gt; eval $1='${s1_val}${s2_val}' avoids problems,
# ==&gt; if one of the variables contains a single quote.
}
#:docstring strcmp:
# Usage: strcmp $s1 $s2
#
# Strcmp compares its arguments and returns an integer less than, equal to,
# or greater than zero, depending on whether string s1 is lexicographically
# less than, equal to, or greater than string s2.
#:end docstring:
###;;;autoload
function strcmp ()
{
[ "$1" = "$2" ] && return 0
[ "${1}" '<' "${2}" ] &gt; /dev/null && return -1
return 1
}
#:docstring strncmp:
# Usage: strncmp $s1 $s2 $n
#
# Like strcmp, but makes the comparison by examining a maximum of n
# characters (n less than or equal to zero yields equality).
#:end docstring:
###;;;autoload
function strncmp ()
{
if [ -z "${3}" -o "${3}" -le "0" ]; then
return 0
fi
if [ ${3} -ge ${#1} -a ${3} -ge ${#2} ]; then
strcmp "$1" "$2"
return $?
else
s1=${1:0:$3}
s2=${2:0:$3}
strcmp $s1 $s2
return $?
fi
}
#:docstring strlen:
# Usage: strlen s
#
# Strlen returns the number of characters in string literal s.
#:end docstring:
###;;;autoload
function strlen ()
{
eval echo "\${#${1}}"
# ==&gt; Returns the length of the value of the variable
# ==&gt; whose name is passed as an argument.
}
#:docstring strspn:
# Usage: strspn $s1 $s2
#
# Strspn returns the length of the maximum initial segment of string s1,
# which consists entirely of characters from string s2.
#:end docstring:
###;;;autoload
function strspn ()
{
# Unsetting IFS allows whitespace to be handled as normal chars.
local IFS=
local result="${1%%[!${2}]*}"
echo ${#result}
}
#:docstring strcspn:
# Usage: strcspn $s1 $s2
#
# Strcspn returns the length of the maximum initial segment of string s1,
# which consists entirely of characters not from string s2.
#:end docstring:
###;;;autoload
function strcspn ()
{
# Unsetting IFS allows whitspace to be handled as normal chars.
local IFS=
local result="${1%%[${2}]*}"
echo ${#result}
}
#:docstring strstr:
# Usage: strstr s1 s2
#
# Strstr echoes a substring starting at the first occurrence of string s2 in
# string s1, or nothing if s2 does not occur in the string. If s2 points to
# a string of zero length, strstr echoes s1.
#:end docstring:
###;;;autoload
function strstr ()
{
# if s2 points to a string of zero length, strstr echoes s1
[ ${#2} -eq 0 ] && { echo "$1" ; return 0; }
# strstr echoes nothing if s2 does not occur in s1
case "$1" in
*$2*) ;;
*) return 1;;
esac
# use the pattern matching code to strip off the match and everything
# following it
first=${1/$2*/}
# then strip off the first unmatched portion of the string
echo "${1##$first}"
}
#:docstring strtok:
# Usage: strtok s1 s2
#
# Strtok considers the string s1 to consist of a sequence of zero or more
# text tokens separated by spans of one or more characters from the
# separator string s2. The first call (with a non-empty string s1
# specified) echoes a string consisting of the first token on stdout. The
# function keeps track of its position in the string s1 between separate
# calls, so that subsequent calls made with the first argument an empty
# string will work through the string immediately following that token. In
# this way subsequent calls will work through the string s1 until no tokens
# remain. The separator string s2 may be different from call to call.
# When no token remains in s1, an empty value is echoed on stdout.
#:end docstring:
###;;;autoload
function strtok ()
{
:
}
#:docstring strtrunc:
# Usage: strtrunc $n $s1 {$s2} {$...}
#
# Used by many functions like strncmp to truncate arguments for comparison.
# Echoes the first n characters of each string s1 s2 ... on stdout.
#:end docstring:
###;;;autoload
function strtrunc ()
{
n=$1 ; shift
for z; do
echo "${z:0:$n}"
done
}
# provide string
# string.bash ends here
# ========================================================================== #
# ==&gt; Everything below here added by the document author.
# ==&gt; Suggested use of this script is to delete everything below here,
# ==&gt; and "source" this file into your own scripts.
# strcat
string0=one
string1=two
echo
echo "Testing \"strcat\" function:"
echo "Original \"string0\" = $string0"
echo "\"string1\" = $string1"
strcat string0 string1
echo "New \"string0\" = $string0"
echo
# strlen
echo
echo "Testing \"strlen\" function:"
str=123456789
echo "\"str\" = $str"
echo -n "Length of \"str\" = "
strlen str
echo
# Exercise:
# --------
# Add code to test all the other string functions above.
exit 0
#! /bin/bash
# directory-info.sh
# Parses and lists directory information.
# NOTE: Change lines 273 and 353 per "README" file.
# Michael Zick is the author of this script.
# Used here with his permission.
# Controls
# If overridden by command arguments, they must be in the order:
# Arg1: "Descriptor Directory"
# Arg2: "Exclude Paths"
# Arg3: "Exclude Directories"
#
# Environment Settings override Defaults.
# Command arguments override Environment Settings.
# Default location for content addressed file descriptors.
MD5UCFS=${1:-${MD5UCFS:-'/tmpfs/ucfs'}}
# Directory paths never to list or enter
declare -a \
EXCLUDE_PATHS=${2:-${EXCLUDE_PATHS:-'(/proc /dev /devfs /tmpfs)'}}
# Directories never to list or enter
declare -a \
EXCLUDE_DIRS=${3:-${EXCLUDE_DIRS:-'(ucfs lost+found tmp wtmp)'}}
# Files never to list or enter
declare -a \
EXCLUDE_FILES=${3:-${EXCLUDE_FILES:-'(core "Name with Spaces")'}}
# Here document used as a comment block.
: <<LSfieldsDoc
# # # # # List Filesystem Directory Information # # # # #
#
# ListDirectory "FileGlob" "Field-Array-Name"
# or
# ListDirectory -of "FileGlob" "Field-Array-Filename"
# '-of' meaning 'output to filename'
# # # # #
String format description based on: ls (GNU fileutils) version 4.0.36
Produces a line (or more) formatted:
inode permissions hard-links owner group ...
32736 -rw------- 1 mszick mszick
size day month date hh:mm:ss year path
2756608 Sun Apr 20 08:53:06 2003 /home/mszick/core
Unless it is formatted:
inode permissions hard-links owner group ...
266705 crw-rw---- 1 root uucp
major minor day month date hh:mm:ss year path
4, 68 Sun Apr 20 09:27:33 2003 /dev/ttyS4
NOTE: that pesky comma after the major number
NOTE: the 'path' may be multiple fields:
/home/mszick/core
/proc/982/fd/0 -&gt; /dev/null
/proc/982/fd/1 -&gt; /home/mszick/.xsession-errors
/proc/982/fd/13 -&gt; /tmp/tmpfZVVOCs (deleted)
/proc/982/fd/7 -&gt; /tmp/kde-mszick/ksycoca
/proc/982/fd/8 -&gt; socket:[11586]
/proc/982/fd/9 -&gt; pipe:[11588]
If that isn't enough to keep your parser guessing,
either or both of the path components may be relative:
../Built-Shared -&gt; Built-Static
../linux-2.4.20.tar.bz2 -&gt; ../../../SRCS/linux-2.4.20.tar.bz2
The first character of the 11 (10?) character permissions field:
's' Socket
'd' Directory
'b' Block device
'c' Character device
'l' Symbolic link
NOTE: Hard links not marked - test for identical inode numbers
on identical filesystems.
All information about hard linked files are shared, except
for the names and the name's location in the directory system.
NOTE: A "Hard link" is known as a "File Alias" on some systems.
'-' An undistingushed file
Followed by three groups of letters for: User, Group, Others
Character 1: '-' Not readable; 'r' Readable
Character 2: '-' Not writable; 'w' Writable
Character 3, User and Group: Combined execute and special
'-' Not Executable, Not Special
'x' Executable, Not Special
's' Executable, Special
'S' Not Executable, Special
Character 3, Others: Combined execute and sticky (tacky?)
'-' Not Executable, Not Tacky
'x' Executable, Not Tacky
't' Executable, Tacky
'T' Not Executable, Tacky
Followed by an access indicator
Haven't tested this one, it may be the eleventh character
or it may generate another field
' ' No alternate access
'+' Alternate access
LSfieldsDoc
ListDirectory()
{
local -a T
local -i of=0 # Default return in variable
# OLD_IFS=$IFS # Using BASH default ' \t\n'
case "$#" in
3) case "$1" in
-of) of=1 ; shift ;;
* ) return 1 ;;
esac ;;
2) : ;; # Poor man's "continue"
*) return 1 ;;
esac
# NOTE: the (ls) command is NOT quoted (")
T=( $(ls --inode --ignore-backups --almost-all --directory \
--full-time --color=none --time=status --sort=none \
--format=long $1) )
case $of in
# Assign T back to the array whose name was passed as $2
0) eval $2=\( \"\$\{T\[@\]\}\" \) ;;
# Write T into filename passed as $2
1) echo "${T[@]}" &gt; "$2" ;;
esac
return 0
}
# # # # # Is that string a legal number? # # # # #
#
# IsNumber "Var"
# # # # # There has to be a better way, sigh...
IsNumber()
{
local -i int
if [ $# -eq 0 ]
then
return 1
else
(let int=$1) 2&gt;/dev/null
return $? # Exit status of the let thread
fi
}
# # # # # Index Filesystem Directory Information # # # # #
#
# IndexList "Field-Array-Name" "Index-Array-Name"
# or
# IndexList -if Field-Array-Filename Index-Array-Name
# IndexList -of Field-Array-Name Index-Array-Filename
# IndexList -if -of Field-Array-Filename Index-Array-Filename
# # # # #
: <<IndexListDoc
Walk an array of directory fields produced by ListDirectory
Having suppressed the line breaks in an otherwise line oriented
report, build an index to the array element which starts each line.
Each line gets two index entries, the first element of each line
(inode) and the element that holds the pathname of the file.
The first index entry pair (Line-Number==0) are informational:
Index-Array-Name[0] : Number of "Lines" indexed
Index-Array-Name[1] : "Current Line" pointer into Index-Array-Name
The following index pairs (if any) hold element indexes into
the Field-Array-Name per:
Index-Array-Name[Line-Number * 2] : The "inode" field element.
NOTE: This distance may be either +11 or +12 elements.
Index-Array-Name[(Line-Number * 2) + 1] : The "pathname" element.
NOTE: This distance may be a variable number of elements.
Next line index pair for Line-Number+1.
IndexListDoc
IndexList()
{
local -a LIST # Local of listname passed
local -a -i INDEX=( 0 0 ) # Local of index to return
local -i Lidx Lcnt
local -i if=0 of=0 # Default to variable names
case "$#" in # Simplistic option testing
0) return 1 ;;
1) return 1 ;;
2) : ;; # Poor man's continue
3) case "$1" in
-if) if=1 ;;
-of) of=1 ;;
* ) return 1 ;;
esac ; shift ;;
4) if=1 ; of=1 ; shift ; shift ;;
*) return 1
esac
# Make local copy of list
case "$if" in
0) eval LIST=\( \"\$\{$1\[@\]\}\" \) ;;
1) LIST=( $(cat $1) ) ;;
esac
# Grok (grope?) the array
Lcnt=${#LIST[@]}
Lidx=0
until (( Lidx &gt;= Lcnt ))
do
if IsNumber ${LIST[$Lidx]}
then
local -i inode name
local ft
inode=Lidx
local m=${LIST[$Lidx+2]} # Hard Links field
ft=${LIST[$Lidx+1]:0:1} # Fast-Stat
case $ft in
b) ((Lidx+=12)) ;; # Block device
c) ((Lidx+=12)) ;; # Character device
*) ((Lidx+=11)) ;; # Anything else
esac
name=Lidx
case $ft in
-) ((Lidx+=1)) ;; # The easy one
b) ((Lidx+=1)) ;; # Block device
c) ((Lidx+=1)) ;; # Character device
d) ((Lidx+=1)) ;; # The other easy one
l) ((Lidx+=3)) ;; # At LEAST two more fields
# A little more elegance here would handle pipes,
#+ sockets, deleted files - later.
*) until IsNumber ${LIST[$Lidx]} || ((Lidx &gt;= Lcnt))
do
((Lidx+=1))
done
;; # Not required
esac
INDEX[${#INDEX[*]}]=$inode
INDEX[${#INDEX[*]}]=$name
INDEX[0]=${INDEX[0]}+1 # One more "line" found
# echo "Line: ${INDEX[0]} Type: $ft Links: $m Inode: \
# ${LIST[$inode]} Name: ${LIST[$name]}"
else
((Lidx+=1))
fi
done
case "$of" in
0) eval $2=\( \"\$\{INDEX\[@\]\}\" \) ;;
1) echo "${INDEX[@]}" &gt; "$2" ;;
esac
return 0 # What could go wrong?
}
# # # # # Content Identify File # # # # #
#
# DigestFile Input-Array-Name Digest-Array-Name
# or
# DigestFile -if Input-FileName Digest-Array-Name
# # # # #
# Here document used as a comment block.
: <<DigestFilesDoc
The key (no pun intended) to a Unified Content File System (UCFS)
is to distinguish the files in the system based on their content.
Distinguishing files by their name is just so 20th Century.
The content is distinguished by computing a checksum of that content.
This version uses the md5sum program to generate a 128 bit checksum
representative of the file's contents.
There is a chance that two files having different content might
generate the same checksum using md5sum (or any checksum). Should
that become a problem, then the use of md5sum can be replace by a
cyrptographic signature. But until then...
The md5sum program is documented as outputting three fields (and it
does), but when read it appears as two fields (array elements). This
is caused by the lack of whitespace between the second and third field.
So this function gropes the md5sum output and returns:
[0] 32 character checksum in hexidecimal (UCFS filename)
[1] Single character: ' ' text file, '*' binary file
[2] Filesystem (20th Century Style) name
Note: That name may be the character '-' indicating STDIN read.
DigestFilesDoc
DigestFile()
{
local if=0 # Default, variable name
local -a T1 T2
case "$#" in
3) case "$1" in
-if) if=1 ; shift ;;
* ) return 1 ;;
esac ;;
2) : ;; # Poor man's "continue"
*) return 1 ;;
esac
case $if in
0) eval T1=\( \"\$\{$1\[@\]\}\" \)
T2=( $(echo ${T1[@]} | md5sum -) )
;;
1) T2=( $(md5sum $1) )
;;
esac
case ${#T2[@]} in
0) return 1 ;;
1) return 1 ;;
2) case ${T2[1]:0:1} in # SanScrit-2.0.5
\*) T2[${#T2[@]}]=${T2[1]:1}
T2[1]=\*
;;
*) T2[${#T2[@]}]=${T2[1]}
T2[1]=" "
;;
esac
;;
3) : ;; # Assume it worked
*) return 1 ;;
esac
local -i len=${#T2[0]}
if [ $len -ne 32 ] ; then return 1 ; fi
eval $2=\( \"\$\{T2\[@\]\}\" \)
}
# # # # # Locate File # # # # #
#
# LocateFile [-l] FileName Location-Array-Name
# or
# LocateFile [-l] -of FileName Location-Array-FileName
# # # # #
# A file location is Filesystem-id and inode-number
# Here document used as a comment block.
: <<StatFieldsDoc
Based on stat, version 2.2
stat -t and stat -lt fields
[0] name
[1] Total size
File - number of bytes
Symbolic link - string length of pathname
[2] Number of (512 byte) blocks allocated
[3] File type and Access rights (hex)
[4] User ID of owner
[5] Group ID of owner
[6] Device number
[7] Inode number
[8] Number of hard links
[9] Device type (if inode device) Major
[10] Device type (if inode device) Minor
[11] Time of last access
May be disabled in 'mount' with noatime
atime of files changed by exec, read, pipe, utime, mknod (mmap?)
atime of directories changed by addition/deletion of files
[12] Time of last modification
mtime of files changed by write, truncate, utime, mknod
mtime of directories changed by addtition/deletion of files
[13] Time of last change
ctime reflects time of changed inode information (owner, group
permissions, link count
-*-*- Per:
Return code: 0
Size of array: 14
Contents of array
Element 0: /home/mszick
Element 1: 4096
Element 2: 8
Element 3: 41e8
Element 4: 500
Element 5: 500
Element 6: 303
Element 7: 32385
Element 8: 22
Element 9: 0
Element 10: 0
Element 11: 1051221030
Element 12: 1051214068
Element 13: 1051214068
For a link in the form of linkname -&gt; realname
stat -t linkname returns the linkname (link) information
stat -lt linkname returns the realname information
stat -tf and stat -ltf fields
[0] name
[1] ID-0? # Maybe someday, but Linux stat structure
[2] ID-0? # does not have either LABEL nor UUID
# fields, currently information must come
# from file-system specific utilities
These will be munged into:
[1] UUID if possible
[2] Volume Label if possible
Note: 'mount -l' does return the label and could return the UUID
[3] Maximum length of filenames
[4] Filesystem type
[5] Total blocks in the filesystem
[6] Free blocks
[7] Free blocks for non-root user(s)
[8] Block size of the filesystem
[9] Total inodes
[10] Free inodes
-*-*- Per:
Return code: 0
Size of array: 11
Contents of array
Element 0: /home/mszick
Element 1: 0
Element 2: 0
Element 3: 255
Element 4: ef53
Element 5: 2581445
Element 6: 2277180
Element 7: 2146050
Element 8: 4096
Element 9: 1311552
Element 10: 1276425
StatFieldsDoc
# LocateFile [-l] FileName Location-Array-Name
# LocateFile [-l] -of FileName Location-Array-FileName
LocateFile()
{
local -a LOC LOC1 LOC2
local lk="" of=0
case "$#" in
0) return 1 ;;
1) return 1 ;;
2) : ;;
*) while (( "$#" &gt; 2 ))
do
case "$1" in
-l) lk=-1 ;;
-of) of=1 ;;
*) return 1 ;;
esac
shift
done ;;
esac
# More Sanscrit-2.0.5
# LOC1=( $(stat -t $lk $1) )
# LOC2=( $(stat -tf $lk $1) )
# Uncomment above two lines if system has "stat" command installed.
LOC=( ${LOC1[@]:0:1} ${LOC1[@]:3:11}
${LOC2[@]:1:2} ${LOC2[@]:4:1} )
case "$of" in
0) eval $2=\( \"\$\{LOC\[@\]\}\" \) ;;
1) echo "${LOC[@]}" &gt; "$2" ;;
esac
return 0
# Which yields (if you are lucky, and have "stat" installed)
# -*-*- Location Discriptor -*-*-
# Return code: 0
# Size of array: 15
# Contents of array
# Element 0: /home/mszick 20th Century name
# Element 1: 41e8 Type and Permissions
# Element 2: 500 User
# Element 3: 500 Group
# Element 4: 303 Device
# Element 5: 32385 inode
# Element 6: 22 Link count
# Element 7: 0 Device Major
# Element 8: 0 Device Minor
# Element 9: 1051224608 Last Access
# Element 10: 1051214068 Last Modify
# Element 11: 1051214068 Last Status
# Element 12: 0 UUID (to be)
# Element 13: 0 Volume Label (to be)
# Element 14: ef53 Filesystem type
}
# And then there was some test code
ListArray() # ListArray Name
{
local -a Ta
eval Ta=\( \"\$\{$1\[@\]\}\" \)
echo
echo "-*-*- List of Array -*-*-"
echo "Size of array $1: ${#Ta[*]}"
echo "Contents of array $1:"
for (( i=0 ; i<${#Ta[*]} ; i++ ))
do
echo -e "\tElement $i: ${Ta[$i]}"
done
return 0
}
declare -a CUR_DIR
# For small arrays
ListDirectory "${PWD}" CUR_DIR
ListArray CUR_DIR
declare -a DIR_DIG
DigestFile CUR_DIR DIR_DIG
echo "The new \"name\" (checksum) for ${CUR_DIR[9]} is ${DIR_DIG[0]}"
declare -a DIR_ENT
# BIG_DIR # For really big arrays - use a temporary file in ramdisk
# BIG-DIR # ListDirectory -of "${CUR_DIR[11]}/*" "/tmpfs/junk2"
ListDirectory "${CUR_DIR[11]}/*" DIR_ENT
declare -a DIR_IDX
# BIG-DIR # IndexList -if "/tmpfs/junk2" DIR_IDX
IndexList DIR_ENT DIR_IDX
declare -a IDX_DIG
# BIG-DIR # DIR_ENT=( $(cat /tmpfs/junk2) )
# BIG-DIR # DigestFile -if /tmpfs/junk2 IDX_DIG
DigestFile DIR_ENT IDX_DIG
# Small (should) be able to parallize IndexList & DigestFile
# Large (should) be able to parallize IndexList & DigestFile & the assignment
echo "The \"name\" (checksum) for the contents of ${PWD} is ${IDX_DIG[0]}"
declare -a FILE_LOC
LocateFile ${PWD} FILE_LOC
ListArray FILE_LOC
exit 0
# Hash:
# Hash function library
# Author: Mariusz Gniazdowski <mariusz.gn-at-gmail.com&gt;
# Date: 2005-04-07
# Functions making emulating hashes in Bash a little less painful.
# Limitations:
# * Only global variables are supported.
# * Each hash instance generates one global variable per value.
# * Variable names collisions are possible
#+ if you define variable like __hash__hashname_key
# * Keys must use chars that can be part of a Bash variable name
#+ (no dashes, periods, etc.).
# * The hash is created as a variable:
# ... hashname_keyname
# So if somone will create hashes like:
# myhash_ + mykey = myhash__mykey
# myhash + _mykey = myhash__mykey
# Then there will be a collision.
# (This should not pose a major problem.)
Hash_config_varname_prefix=__hash__
# Emulates: hash[key]=value
#
# Params:
# 1 - hash
# 2 - key
# 3 - value
function hash_set {
eval "${Hash_config_varname_prefix}${1}_${2}=\"${3}\""
}
# Emulates: value=hash[key]
#
# Params:
# 1 - hash
# 2 - key
# 3 - value (name of global variable to set)
function hash_get_into {
eval "$3=\"\$${Hash_config_varname_prefix}${1}_${2}\""
}
# Emulates: echo hash[key]
#
# Params:
# 1 - hash
# 2 - key
# 3 - echo params (like -n, for example)
function hash_echo {
eval "echo $3 \"\$${Hash_config_varname_prefix}${1}_${2}\""
}
# Emulates: hash1[key1]=hash2[key2]
#
# Params:
# 1 - hash1
# 2 - key1
# 3 - hash2
# 4 - key2
function hash_copy {
eval "${Hash_config_varname_prefix}${1}_${2}\
=\"\$${Hash_config_varname_prefix}${3}_${4}\""
}
# Emulates: hash[keyN-1]=hash[key2]=...hash[key1]
#
# Copies first key to rest of keys.
#
# Params:
# 1 - hash1
# 2 - key1
# 3 - key2
# . . .
# N - keyN
function hash_dup {
local hashName="$1" keyName="$2"
shift 2
until [ ${#} -le 0 ]; do
eval "${Hash_config_varname_prefix}${hashName}_${1}\
=\"\$${Hash_config_varname_prefix}${hashName}_${keyName}\""
shift;
done;
}
# Emulates: unset hash[key]
#
# Params:
# 1 - hash
# 2 - key
function hash_unset {
eval "unset ${Hash_config_varname_prefix}${1}_${2}"
}
# Emulates something similar to: ref=&hash[key]
#
# The reference is name of the variable in which value is held.
#
# Params:
# 1 - hash
# 2 - key
# 3 - ref - Name of global variable to set.
function hash_get_ref_into {
eval "$3=\"${Hash_config_varname_prefix}${1}_${2}\""
}
# Emulates something similar to: echo &hash[key]
#
# That reference is name of variable in which value is held.
#
# Params:
# 1 - hash
# 2 - key
# 3 - echo params (like -n for example)
function hash_echo_ref {
eval "echo $3 \"${Hash_config_varname_prefix}${1}_${2}\""
}
# Emulates something similar to: $$hash[key](param1, param2, ...)
#
# Params:
# 1 - hash
# 2 - key
# 3,4, ... - Function parameters
function hash_call {
local hash key
hash=$1
key=$2
shift 2
eval "eval \"\$${Hash_config_varname_prefix}${hash}_${key} \\\"\\\$@\\\"\""
}
# Emulates something similar to: isset(hash[key]) or hash[key]==NULL
#
# Params:
# 1 - hash
# 2 - key
# Returns:
# 0 - there is such key
# 1 - there is no such key
function hash_is_set {
eval "if [[ \"\${${Hash_config_varname_prefix}${1}_${2}-a}\" = \"a\" &&
\"\${${Hash_config_varname_prefix}${1}_${2}-b}\" = \"b\" ]]
then return 1; else return 0; fi"
}
# Emulates something similar to:
# foreach($hash as $key =&gt; $value) { fun($key,$value); }
#
# It is possible to write different variations of this function.
# Here we use a function call to make it as "generic" as possible.
#
# Params:
# 1 - hash
# 2 - function name
function hash_foreach {
local keyname oldIFS="$IFS"
IFS=' '
for i in $(eval "echo \${!${Hash_config_varname_prefix}${1}_*}"); do
keyname=$(eval "echo \${i##${Hash_config_varname_prefix}${1}_}")
eval "$2 $keyname \"\$$i\""
done
IFS="$oldIFS"
}
# NOTE: In lines 103 and 116, ampersand changed.
# But, it doesn't matter, because these are comment lines anyhow.
#!/bin/bash
# hash-example.sh: Colorizing text.
# Author: Mariusz Gniazdowski <mariusz.gn-at-gmail.com&gt;
. Hash.lib # Load the library of functions.
hash_set colors red "\033[0;31m"
hash_set colors blue "\033[0;34m"
hash_set colors light_blue "\033[1;34m"
hash_set colors light_red "\033[1;31m"
hash_set colors cyan "\033[0;36m"
hash_set colors light_green "\033[1;32m"
hash_set colors light_gray "\033[0;37m"
hash_set colors green "\033[0;32m"
hash_set colors yellow "\033[1;33m"
hash_set colors light_purple "\033[1;35m"
hash_set colors purple "\033[0;35m"
hash_set colors reset_color "\033[0;00m"
# $1 - keyname
# $2 - value
try_colors() {
echo -en "$2"
echo "This line is $1."
}
hash_foreach colors try_colors
hash_echo colors reset_color -en
echo -e '\nLet us overwrite some colors with yellow.\n'
# It's hard to read yellow text on some terminals.
hash_dup colors yellow red light_green blue green light_gray cyan
hash_foreach colors try_colors
hash_echo colors reset_color -en
echo -e '\nLet us delete them and try colors once more . . .\n'
for i in red light_green blue green light_gray cyan; do
hash_unset colors $i
done
hash_foreach colors try_colors
hash_echo colors reset_color -en
hash_set other txt "Other examples . . ."
hash_echo other txt
hash_get_into other txt text
echo $text
hash_set other my_fun try_colors
hash_call other my_fun purple "`hash_echo colors purple`"
hash_echo colors reset_color -en
echo; echo "Back to normal?"; echo
exit $?
# On some terminals, the "light" colors print in bold,
# and end up looking darker than the normal ones.
# Why is this?
#!/bin/bash
# $Id: ha.sh,v 1.2 2005/04/21 23:24:26 oliver Exp $
# Copyright 2005 Oliver Beckstein
# Released under the GNU Public License
# Author of script granted permission for inclusion in ABS Guide.
# (Thank you!)
#----------------------------------------------------------------
# pseudo hash based on indirect parameter expansion
# API: access through functions:
#
# create the hash:
#
# newhash Lovers
#
# add entries (note single quotes for spaces)
#
# addhash Lovers Tristan Isolde
# addhash Lovers 'Romeo Montague' 'Juliet Capulet'
#
# access value by key
#
# gethash Lovers Tristan ----&gt; Isolde
#
# show all keys
#
# keyshash Lovers ----&gt; 'Tristan' 'Romeo Montague'
#
#
# Convention: instead of perls' foo{bar} = boing' syntax,
# use
# '_foo_bar=boing' (two underscores, no spaces)
#
# 1) store key in _NAME_keys[]
# 2) store value in _NAME_values[] using the same integer index
# The integer index for the last entry is _NAME_ptr
#
# NOTE: No error or sanity checks, just bare bones.
function _inihash () {
# private function
# call at the beginning of each procedure
# defines: _keys _values _ptr
#
# Usage: _inihash NAME
local name=$1
_keys=_${name}_keys
_values=_${name}_values
_ptr=_${name}_ptr
}
function newhash () {
# Usage: newhash NAME
# NAME should not contain spaces or dots.
# Actually: it must be a legal name for a Bash variable.
# We rely on Bash automatically recognising arrays.
local name=$1
local _keys _values _ptr
_inihash ${name}
eval ${_ptr}=0
}
function addhash () {
# Usage: addhash NAME KEY 'VALUE with spaces'
# arguments with spaces need to be quoted with single quotes ''
local name=$1 k="$2" v="$3"
local _keys _values _ptr
_inihash ${name}
#echo "DEBUG(addhash): ${_ptr}=${!_ptr}"
eval let ${_ptr}=${_ptr}+1
eval "$_keys[${!_ptr}]=\"${k}\""
eval "$_values[${!_ptr}]=\"${v}\""
}
function gethash () {
# Usage: gethash NAME KEY
# Returns boing
# ERR=0 if entry found, 1 otherwise
# That's not a proper hash --
#+ we simply linearly search through the keys.
local name=$1 key="$2"
local _keys _values _ptr
local k v i found h
_inihash ${name}
# _ptr holds the highest index in the hash
found=0
for i in $(seq 1 ${!_ptr}); do
h="\${${_keys}[${i}]}" # Safer to do it in two steps,
eval k=${h} #+ especially when quoting for spaces.
if [ "${k}" = "${key}" ]; then found=1; break; fi
done;
[ ${found} = 0 ] && return 1;
# else: i is the index that matches the key
h="\${${_values}[${i}]}"
eval echo "${h}"
return 0;
}
function keyshash () {
# Usage: keyshash NAME
# Returns list of all keys defined for hash name.
local name=$1 key="$2"
local _keys _values _ptr
local k i h
_inihash ${name}
# _ptr holds the highest index in the hash
for i in $(seq 1 ${!_ptr}); do
h="\${${_keys}[${i}]}" # Safer to do it in two steps,
eval k=${h} #+ especially when quoting for spaces.
echo -n "'${k}' "
done;
}
# -----------------------------------------------------------------------
# Now, let's test it.
# (Per comments at the beginning of the script.)
newhash Lovers
addhash Lovers Tristan Isolde
addhash Lovers 'Romeo Montague' 'Juliet Capulet'
# Output results.
echo
gethash Lovers Tristan # Isolde
echo
keyshash Lovers # 'Tristan' 'Romeo Montague'
echo; echo
exit 0
# Exercise:
# --------
# Add error checks to the functions.
#!/bin/bash
# ==&gt; usb.sh
# ==&gt; Script for mounting and installing pen/keychain USB storage devices.
# ==&gt; Runs as root at system startup (see below).
# ==&gt;
# ==&gt; Newer Linux distros (2004 or later) autodetect
# ==&gt; and install USB pen drives, and therefore don't need this script.
# ==&gt; But, it's still instructive.
# This code is free software covered by GNU GPL license version 2 or above.
# Please refer to http://www.gnu.org/ for the full license text.
#
# Some code lifted from usb-mount by Michael Hamilton's usb-mount (LGPL)
#+ see http://users.actrix.co.nz/michael/usbmount.html
#
# INSTALL
# -------
# Put this in /etc/hotplug/usb/diskonkey.
# Then look in /etc/hotplug/usb.distmap, and copy all usb-storage entries
#+ into /etc/hotplug/usb.usermap, substituting "usb-storage" for "diskonkey".
# Otherwise this code is only run during the kernel module invocation/removal
#+ (at least in my tests), which defeats the purpose.
#
# TODO
# ----
# Handle more than one diskonkey device at one time (e.g. /dev/diskonkey1
#+ and /mnt/diskonkey1), etc. The biggest problem here is the handling in
#+ devlabel, which I haven't yet tried.
#
# AUTHOR and SUPPORT
# ------------------
# Konstantin Riabitsev, <icon linux duke edu&gt;.
# Send any problem reports to my email address at the moment.
#
# ==&gt; Comments added by ABS Guide author.
SYMLINKDEV=/dev/diskonkey
MOUNTPOINT=/mnt/diskonkey
DEVLABEL=/sbin/devlabel
DEVLABELCONFIG=/etc/sysconfig/devlabel
IAM=$0
##
# Functions lifted near-verbatim from usb-mount code.
#
function allAttachedScsiUsb {
find /proc/scsi/ -path '/proc/scsi/usb-storage*' -type f |
xargs grep -l 'Attached: Yes'
}
function scsiDevFromScsiUsb {
echo $1 | awk -F"[-/]" '{ n=$(NF-1);
print "/dev/sd" substr("abcdefghijklmnopqrstuvwxyz", n+1, 1) }'
}
if [ "${ACTION}" = "add" ] && [ -f "${DEVICE}" ]; then
##
# lifted from usbcam code.
#
if [ -f /var/run/console.lock ]; then
CONSOLEOWNER=`cat /var/run/console.lock`
elif [ -f /var/lock/console.lock ]; then
CONSOLEOWNER=`cat /var/lock/console.lock`
else
CONSOLEOWNER=
fi
for procEntry in $(allAttachedScsiUsb); do
scsiDev=$(scsiDevFromScsiUsb $procEntry)
# Some bug with usb-storage?
# Partitions are not in /proc/partitions until they are accessed
#+ somehow.
/sbin/fdisk -l $scsiDev &gt;/dev/null
##
# Most devices have partitioning info, so the data would be on
#+ /dev/sd?1. However, some stupider ones don't have any partitioning
#+ and use the entire device for data storage. This tries to
#+ guess semi-intelligently if we have a /dev/sd?1 and if not, then
#+ it uses the entire device and hopes for the better.
#
if grep -q `basename $scsiDev`1 /proc/partitions; then
part="$scsiDev""1"
else
part=$scsiDev
fi
##
# Change ownership of the partition to the console user so they can
#+ mount it.
#
if [ ! -z "$CONSOLEOWNER" ]; then
chown $CONSOLEOWNER:disk $part
fi
##
# This checks if we already have this UUID defined with devlabel.
# If not, it then adds the device to the list.
#
prodid=`$DEVLABEL printid -d $part`
if ! grep -q $prodid $DEVLABELCONFIG; then
# cross our fingers and hope it works
$DEVLABEL add -d $part -s $SYMLINKDEV 2&gt;/dev/null
fi
##
# Check if the mount point exists and create if it doesn't.
#
if [ ! -e $MOUNTPOINT ]; then
mkdir -p $MOUNTPOINT
fi
##
# Take care of /etc/fstab so mounting is easy.
#
if ! grep -q "^$SYMLINKDEV" /etc/fstab; then
# Add an fstab entry
echo -e \
"$SYMLINKDEV\t\t$MOUNTPOINT\t\tauto\tnoauto,owner,kudzu 0 0" \
&gt;&gt; /etc/fstab
fi
done
if [ ! -z "$REMOVER" ]; then
##
# Make sure this script is triggered on device removal.
#
mkdir -p `dirname $REMOVER`
ln -s $IAM $REMOVER
fi
elif [ "${ACTION}" = "remove" ]; then
##
# If the device is mounted, unmount it cleanly.
#
if grep -q "$MOUNTPOINT" /etc/mtab; then
# unmount cleanly
umount -l $MOUNTPOINT
fi
##
# Remove it from /etc/fstab if it's there.
#
if grep -q "^$SYMLINKDEV" /etc/fstab; then
grep -v "^$SYMLINKDEV" /etc/fstab &gt; /etc/.fstab.new
mv -f /etc/.fstab.new /etc/fstab
fi
fi
exit 0
#!/bin/bash
# tohtml.sh [v. 0.2.01, reldate: 04/13/12, a teeny bit less buggy]
# Convert a text file to HTML format.
# Author: Mendel Cooper
# License: GPL3
# Usage: sh tohtml.sh < textfile &gt; htmlfile
# Script can easily be modified to accept source and target filenames.
# Assumptions:
# 1) Paragraphs in (target) text file are separated by a blank line.
# 2) Jpeg images (*.jpg) are located in "images" subdirectory.
# In the target file, the image names are enclosed in square brackets,
# for example, [image01.jpg].
# 3) Emphasized (italic) phrases begin with a space+underscore
#+ or the first character on the line is an underscore,
#+ and end with an underscore+space or underscore+end-of-line.
# Settings
FNTSIZE=2 # Small-medium font size
IMGDIR="images" # Image directory
# Headers
HDR01='<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"&gt;'
HDR02='<!-- Converted to HTML by ***tohtml.sh*** script --&gt;'
HDR03='<!-- script author: M. Leo Cooper <thegrendel.abs@gmail.com&gt; --&gt;'
HDR10='<html&gt;'
HDR11='<head&gt;'
HDR11a='</head&gt;'
HDR12a='<title&gt;'
HDR12b='</title&gt;'
HDR121='<META NAME="GENERATOR" CONTENT="tohtml.sh script"&gt;'
HDR13='<body bgcolor="#dddddd"&gt;' # Change background color to suit.
HDR14a='<font size='
HDR14b='&gt;'
# Footers
FTR10='</body&gt;'
FTR11='</html&gt;'
# Tags
BOLD="<b&gt;"
CENTER="<center&gt;"
END_CENTER="</center&gt;"
LF="<br&gt;"
write_headers ()
{
echo "$HDR01"
echo
echo "$HDR02"
echo "$HDR03"
echo
echo
echo "$HDR10"
echo "$HDR11"
echo "$HDR121"
echo "$HDR11a"
echo "$HDR13"
echo
echo -n "$HDR14a"
echo -n "$FNTSIZE"
echo "$HDR14b"
echo
echo "$BOLD" # Everything in bold (more easily readable).
}
process_text ()
{
while read line # Read one line at a time.
do
{
if [ ! "$line" ] # Blank line?
then # Then new paragraph must follow.
echo
echo "$LF" # Insert two <br&gt; tags.
echo "$LF"
echo
continue # Skip the underscore test.
else # Otherwise . . .
if [[ "$line" =~ \[*jpg\] ]] # Is a graphic?
then # Strip away brackets.
temp=$( echo "$line" | sed -e 's/\[//' -e 's/\]//' )
line=""$CENTER" <img src="\"$IMGDIR"/$temp\"&gt; "$END_CENTER" "
# Add image tag.
# And, center it.
fi
fi
echo "$line" | grep -q _
if [ "$?" -eq 0 ] # If line contains underscore ...
then
# ===================================================
# Convert underscored phrase to italics.
temp=$( echo "$line" |
sed -e 's/ _/ <i&gt;/' -e 's/_/<\/i&gt; /' |
sed -e 's/^_/<i&gt;/' -e 's/_/<\/i&gt;/' )
# Process only underscores prefixed by space,
#+ or at beginning or end of line.
# Do not convert underscores embedded within a word!
line="$temp"
# Slows script execution. Can be optimized?
# ===================================================
fi
# echo
echo "$line"
# echo
# Don't want extra blank lines in generated text!
} # End while
done
} # End process_text ()
write_footers () # Termination tags.
{
echo "$FTR10"
echo "$FTR11"
}
# main () {
# =========
write_headers
process_text
write_footers
# =========
# }
exit $?
# Exercises:
# ---------
# 1) Fixup: Check for closing underscore before a comma or period.
# 2) Add a test for the presence of a closing underscore
#+ in phrases to be italicized.
#!/bin/bash
# archiveweblogs.sh v1.0
# Troy Engel <tengel@fluid.com&gt;
# Slightly modified by document author.
# Used with permission.
#
# This script will preserve the normally rotated and
#+ thrown away weblogs from a default RedHat/Apache installation.
# It will save the files with a date/time stamp in the filename,
#+ bzipped, to a given directory.
#
# Run this from crontab nightly at an off hour,
#+ as bzip2 can suck up some serious CPU on huge logs:
# 0 2 * * * /opt/sbin/archiveweblogs.sh
PROBLEM=66
# Set this to your backup dir.
BKP_DIR=/opt/backups/weblogs
# Default Apache/RedHat stuff
LOG_DAYS="4 3 2 1"
LOG_DIR=/var/log/httpd
LOG_FILES="access_log error_log"
# Default RedHat program locations
LS=/bin/ls
MV=/bin/mv
ID=/usr/bin/id
CUT=/bin/cut
COL=/usr/bin/column
BZ2=/usr/bin/bzip2
# Are we root?
USER=`$ID -u`
if [ "X$USER" != "X0" ]; then
echo "PANIC: Only root can run this script!"
exit $PROBLEM
fi
# Backup dir exists/writable?
if [ ! -x $BKP_DIR ]; then
echo "PANIC: $BKP_DIR doesn't exist or isn't writable!"
exit $PROBLEM
fi
# Move, rename and bzip2 the logs
for logday in $LOG_DAYS; do
for logfile in $LOG_FILES; do
MYFILE="$LOG_DIR/$logfile.$logday"
if [ -w $MYFILE ]; then
DTS=`$LS -lgo --time-style=+%Y%m%d $MYFILE | $COL -t | $CUT -d ' ' -f7`
$MV $MYFILE $BKP_DIR/$logfile.$DTS
$BZ2 $BKP_DIR/$logfile.$DTS
else
# Only spew an error if the file exits (ergo non-writable).
if [ -f $MYFILE ]; then
echo "ERROR: $MYFILE not writable. Skipping."
fi
fi
done
done
exit 0
#! /bin/bash
# protect_literal.sh
# set -vx
:<<-'_Protect_Literal_String_Doc'
Copyright (c) Michael S. Zick, 2003; All Rights Reserved
License: Unrestricted reuse in any form, for any purpose.
Warranty: None
Revision: $ID$
Documentation redirected to the Bash no-operation.
Bash will '/dev/null' this block when the script is first read.
(Uncomment the above set command to see this action.)
Remove the first (Sha-Bang) line when sourcing this as a library
procedure. Also comment out the example use code in the two
places where shown.
Usage:
_protect_literal_str 'Whatever string meets your ${fancy}'
Just echos the argument to standard out, hard quotes
restored.
$(_protect_literal_str 'Whatever string meets your ${fancy}')
as the right-hand-side of an assignment statement.
Does:
As the right-hand-side of an assignment, preserves the
hard quotes protecting the contents of the literal during
assignment.
Notes:
The strange names (_*) are used to avoid trampling on
the user's chosen names when this is sourced as a
library.
_Protect_Literal_String_Doc
# The 'for illustration' function form
_protect_literal_str() {
# Pick an un-used, non-printing character as local IFS.
# Not required, but shows that we are ignoring it.
local IFS=$'\x1B' # \ESC character
# Enclose the All-Elements-Of in hard quotes during assignment.
local tmp=$'\x27'$@$'\x27'
# local tmp=$'\''$@$'\'' # Even uglier.
local len=${#tmp} # Info only.
echo $tmp is $len long. # Output AND information.
}
# This is the short-named version.
_pls() {
local IFS=$'x1B' # \ESC character (not required)
echo $'\x27'$@$'\x27' # Hard quoted parameter glob
}
# :<<-'_Protect_Literal_String_Test'
# # # Remove the above "# " to disable this code. # # #
# See how that looks when printed.
echo
echo "- - Test One - -"
_protect_literal_str 'Hello $user'
_protect_literal_str 'Hello "${username}"'
echo
# Which yields:
# - - Test One - -
# 'Hello $user' is 13 long.
# 'Hello "${username}"' is 21 long.
# Looks as expected, but why all of the trouble?
# The difference is hidden inside the Bash internal order
#+ of operations.
# Which shows when you use it on the RHS of an assignment.
# Declare an array for test values.
declare -a arrayZ
# Assign elements with various types of quotes and escapes.
arrayZ=( zero "$(_pls 'Hello ${Me}')" 'Hello ${You}' "\'Pass: ${pw}\'" )
# Now list that array and see what is there.
echo "- - Test Two - -"
for (( i=0 ; i<${#arrayZ[*]} ; i++ ))
do
echo Element $i: ${arrayZ[$i]} is: ${#arrayZ[$i]} long.
done
echo
# Which yields:
# - - Test Two - -
# Element 0: zero is: 4 long. # Our marker element
# Element 1: 'Hello ${Me}' is: 13 long. # Our "$(_pls '...' )"
# Element 2: Hello ${You} is: 12 long. # Quotes are missing
# Element 3: \'Pass: \' is: 10 long. # ${pw} expanded to nothing
# Now make an assignment with that result.
declare -a array2=( ${arrayZ[@]} )
# And print what happened.
echo "- - Test Three - -"
for (( i=0 ; i<${#array2[*]} ; i++ ))
do
echo Element $i: ${array2[$i]} is: ${#array2[$i]} long.
done
echo
# Which yields:
# - - Test Three - -
# Element 0: zero is: 4 long. # Our marker element.
# Element 1: Hello ${Me} is: 11 long. # Intended result.
# Element 2: Hello is: 5 long. # ${You} expanded to nothing.
# Element 3: 'Pass: is: 6 long. # Split on the whitespace.
# Element 4: ' is: 1 long. # The end quote is here now.
# Our Element 1 has had its leading and trailing hard quotes stripped.
# Although not shown, leading and trailing whitespace is also stripped.
# Now that the string contents are set, Bash will always, internally,
#+ hard quote the contents as required during its operations.
# Why?
# Considering our "$(_pls 'Hello ${Me}')" construction:
# " ... " -&gt; Expansion required, strip the quotes.
# $( ... ) -&gt; Replace with the result of..., strip this.
# _pls ' ... ' -&gt; called with literal arguments, strip the quotes.
# The result returned includes hard quotes; BUT the above processing
#+ has already been done, so they become part of the value assigned.
#
# Similarly, during further usage of the string variable, the ${Me}
#+ is part of the contents (result) and survives any operations
# (Until explicitly told to evaluate the string).
# Hint: See what happens when the hard quotes ($'\x27') are replaced
#+ with soft quotes ($'\x22') in the above procedures.
# Interesting also is to remove the addition of any quoting.
# _Protect_Literal_String_Test
# # # Remove the above "# " to disable this code. # # #
exit 0
#! /bin/bash
# unprotect_literal.sh
# set -vx
:<<-'_UnProtect_Literal_String_Doc'
Copyright (c) Michael S. Zick, 2003; All Rights Reserved
License: Unrestricted reuse in any form, for any purpose.
Warranty: None
Revision: $ID$
Documentation redirected to the Bash no-operation. Bash will
'/dev/null' this block when the script is first read.
(Uncomment the above set command to see this action.)
Remove the first (Sha-Bang) line when sourcing this as a library
procedure. Also comment out the example use code in the two
places where shown.
Usage:
Complement of the "$(_pls 'Literal String')" function.
(See the protect_literal.sh example.)
StringVar=$(_upls ProtectedSringVariable)
Does:
When used on the right-hand-side of an assignment statement;
makes the substitions embedded in the protected string.
Notes:
The strange names (_*) are used to avoid trampling on
the user's chosen names when this is sourced as a
library.
_UnProtect_Literal_String_Doc
_upls() {
local IFS=$'x1B' # \ESC character (not required)
eval echo $@ # Substitution on the glob.
}
# :<<-'_UnProtect_Literal_String_Test'
# # # Remove the above "# " to disable this code. # # #
_pls() {
local IFS=$'x1B' # \ESC character (not required)
echo $'\x27'$@$'\x27' # Hard quoted parameter glob
}
# Declare an array for test values.
declare -a arrayZ
# Assign elements with various types of quotes and escapes.
arrayZ=( zero "$(_pls 'Hello ${Me}')" 'Hello ${You}' "\'Pass: ${pw}\'" )
# Now make an assignment with that result.
declare -a array2=( ${arrayZ[@]} )
# Which yielded:
# - - Test Three - -
# Element 0: zero is: 4 long # Our marker element.
# Element 1: Hello ${Me} is: 11 long # Intended result.
# Element 2: Hello is: 5 long # ${You} expanded to nothing.
# Element 3: 'Pass: is: 6 long # Split on the whitespace.
# Element 4: ' is: 1 long # The end quote is here now.
# set -vx
# Initialize 'Me' to something for the embedded ${Me} substitution.
# This needs to be done ONLY just prior to evaluating the
#+ protected string.
# (This is why it was protected to begin with.)
Me="to the array guy."
# Set a string variable destination to the result.
newVar=$(_upls ${array2[1]})
# Show what the contents are.
echo $newVar
# Do we really need a function to do this?
newerVar=$(eval echo ${array2[1]})
echo $newerVar
# I guess not, but the _upls function gives us a place to hang
#+ the documentation on.
# This helps when we forget what a # construction like:
#+ $(eval echo ... ) means.
# What if Me isn't set when the protected string is evaluated?
unset Me
newestVar=$(_upls ${array2[1]})
echo $newestVar
# Just gone, no hints, no runs, no errors.
# Why in the world?
# Setting the contents of a string variable containing character
#+ sequences that have a meaning in Bash is a general problem in
#+ script programming.
#
# This problem is now solved in eight lines of code
#+ (and four pages of description).
# Where is all this going?
# Dynamic content Web pages as an array of Bash strings.
# Content set per request by a Bash 'eval' command
#+ on the stored page template.
# Not intended to replace PHP, just an interesting thing to do.
###
# Don't have a webserver application?
# No problem, check the example directory of the Bash source;
#+ there is a Bash script for that also.
# _UnProtect_Literal_String_Test
# # # Remove the above "# " to disable this code. # # #
exit 0
#!/bin/bash
# $Id: is_spammer.bash,v 1.12.2.11 2004/10/01 21:42:33 mszick Exp $
# Above line is RCS info.
# The latest version of this script is available from http://www.morethan.org.
#
# Spammer-identification
# by Michael S. Zick
# Used in the ABS Guide with permission.
#######################################################
# Documentation
# See also "Quickstart" at end of script.
#######################################################
:<<-'__is_spammer_Doc_'
Copyright (c) Michael S. Zick, 2004
License: Unrestricted reuse in any form, for any purpose.
Warranty: None -{Its a script; the user is on their own.}-
Impatient?
Application code: goto "# # # Hunt the Spammer' program code # # #"
Example output: ":<<-'_is_spammer_outputs_'"
How to use: Enter script name without arguments.
Or goto "Quickstart" at end of script.
Provides
Given a domain name or IP(v4) address as input:
Does an exhaustive set of queries to find the associated
network resources (short of recursing into TLDs).
Checks the IP(v4) addresses found against Blacklist
nameservers.
If found to be a blacklisted IP(v4) address,
reports the blacklist text records.
(Usually hyper-links to the specific report.)
Requires
A working Internet connection.
(Exercise: Add check and/or abort if not on-line when running script.)
Bash with arrays (2.05b+).
The external program 'dig' --
a utility program provided with the 'bind' set of programs.
Specifically, the version which is part of Bind series 9.x
See: http://www.isc.org
All usages of 'dig' are limited to wrapper functions,
which may be rewritten as required.
See: dig_wrappers.bash for details.
("Additional documentation" -- below)
Usage
Script requires a single argument, which may be:
1) A domain name;
2) An IP(v4) address;
3) A filename, with one name or address per line.
Script accepts an optional second argument, which may be:
1) A Blacklist server name;
2) A filename, with one Blacklist server name per line.
If the second argument is not provided, the script uses
a built-in set of (free) Blacklist servers.
See also, the Quickstart at the end of this script (after 'exit').
Return Codes
0 - All OK
1 - Script failure
2 - Something is Blacklisted
Optional environment variables
SPAMMER_TRACE
If set to a writable file,
script will log an execution flow trace.
SPAMMER_DATA
If set to a writable file, script will dump its
discovered data in the form of GraphViz file.
See: http://www.research.att.com/sw/tools/graphviz
SPAMMER_LIMIT
Limits the depth of resource tracing.
Default is 2 levels.
A setting of 0 (zero) means 'unlimited' . . .
Caution: script might recurse the whole Internet!
A limit of 1 or 2 is most useful when processing
a file of domain names and addresses.
A higher limit can be useful when hunting spam gangs.
Additional documentation
Download the archived set of scripts
explaining and illustrating the function contained within this script.
http://bash.deta.in/mszick_clf.tar.bz2
Study notes
This script uses a large number of functions.
Nearly all general functions have their own example script.
Each of the example scripts have tutorial level comments.
Scripting project
Add support for IP(v6) addresses.
IP(v6) addresses are recognized but not processed.
Advanced project
Add the reverse lookup detail to the discovered information.
Report the delegation chain and abuse contacts.
Modify the GraphViz file output to include the
newly discovered information.
__is_spammer_Doc_
#######################################################
#### Special IFS settings used for string parsing. ####
# Whitespace == :Space:Tab:Line Feed:Carriage Return:
WSP_IFS=$'\x20'$'\x09'$'\x0A'$'\x0D'
# No Whitespace == Line Feed:Carriage Return
NO_WSP=$'\x0A'$'\x0D'
# Field separator for dotted decimal IP addresses
ADR_IFS=${NO_WSP}'.'
# Array to dotted string conversions
DOT_IFS='.'${WSP_IFS}
# # # Pending operations stack machine # # #
# This set of functions described in func_stack.bash.
# (See "Additional documentation" above.)
# # #
# Global stack of pending operations.
declare -f -a _pending_
# Global sentinel for stack runners
declare -i _p_ctrl_
# Global holder for currently executing function
declare -f _pend_current_
# # # Debug version only - remove for regular use # # #
#
# The function stored in _pend_hook_ is called
# immediately before each pending function is
# evaluated. Stack clean, _pend_current_ set.
#
# This thingy demonstrated in pend_hook.bash.
declare -f _pend_hook_
# # #
# The do nothing function
pend_dummy() { : ; }
# Clear and initialize the function stack.
pend_init() {
unset _pending_[@]
pend_func pend_stop_mark
_pend_hook_='pend_dummy' # Debug only.
}
# Discard the top function on the stack.
pend_pop() {
if [ ${#_pending_[@]} -gt 0 ]
then
local -i _top_
_top_=${#_pending_[@]}-1
unset _pending_[$_top_]
fi
}
# pend_func function_name [$(printf '%q\n' arguments)]
pend_func() {
local IFS=${NO_WSP}
set -f
_pending_[${#_pending_[@]}]=$@
set +f
}
# The function which stops the release:
pend_stop_mark() {
_p_ctrl_=0
}
pend_mark() {
pend_func pend_stop_mark
}
# Execute functions until 'pend_stop_mark' . . .
pend_release() {
local -i _top_ # Declare _top_ as integer.
_p_ctrl_=${#_pending_[@]}
while [ ${_p_ctrl_} -gt 0 ]
do
_top_=${#_pending_[@]}-1
_pend_current_=${_pending_[$_top_]}
unset _pending_[$_top_]
$_pend_hook_ # Debug only.
eval $_pend_current_
done
}
# Drop functions until 'pend_stop_mark' . . .
pend_drop() {
local -i _top_
local _pd_ctrl_=${#_pending_[@]}
while [ ${_pd_ctrl_} -gt 0 ]
do
_top_=$_pd_ctrl_-1
if [ "${_pending_[$_top_]}" == 'pend_stop_mark' ]
then
unset _pending_[$_top_]
break
else
unset _pending_[$_top_]
_pd_ctrl_=$_top_
fi
done
if [ ${#_pending_[@]} -eq 0 ]
then
pend_func pend_stop_mark
fi
}
#### Array editors ####
# This function described in edit_exact.bash.
# (See "Additional documentation," above.)
# edit_exact <excludes_array_name&gt; <target_array_name&gt;
edit_exact() {
[ $# -eq 2 ] ||
[ $# -eq 3 ] || return 1
local -a _ee_Excludes
local -a _ee_Target
local _ee_x
local _ee_t
local IFS=${NO_WSP}
set -f
eval _ee_Excludes=\( \$\{$1\[@\]\} \)
eval _ee_Target=\( \$\{$2\[@\]\} \)
local _ee_len=${#_ee_Target[@]} # Original length.
local _ee_cnt=${#_ee_Excludes[@]} # Exclude list length.
[ ${_ee_len} -ne 0 ] || return 0 # Can't edit zero length.
[ ${_ee_cnt} -ne 0 ] || return 0 # Can't edit zero length.
for (( x = 0; x < ${_ee_cnt} ; x++ ))
do
_ee_x=${_ee_Excludes[$x]}
for (( n = 0 ; n < ${_ee_len} ; n++ ))
do
_ee_t=${_ee_Target[$n]}
if [ x"${_ee_t}" == x"${_ee_x}" ]
then
unset _ee_Target[$n] # Discard match.
[ $# -eq 2 ] && break # If 2 arguments, then done.
fi
done
done
eval $2=\( \$\{_ee_Target\[@\]\} \)
set +f
return 0
}
# This function described in edit_by_glob.bash.
# edit_by_glob <excludes_array_name&gt; <target_array_name&gt;
edit_by_glob() {
[ $# -eq 2 ] ||
[ $# -eq 3 ] || return 1
local -a _ebg_Excludes
local -a _ebg_Target
local _ebg_x
local _ebg_t
local IFS=${NO_WSP}
set -f
eval _ebg_Excludes=\( \$\{$1\[@\]\} \)
eval _ebg_Target=\( \$\{$2\[@\]\} \)
local _ebg_len=${#_ebg_Target[@]}
local _ebg_cnt=${#_ebg_Excludes[@]}
[ ${_ebg_len} -ne 0 ] || return 0
[ ${_ebg_cnt} -ne 0 ] || return 0
for (( x = 0; x < ${_ebg_cnt} ; x++ ))
do
_ebg_x=${_ebg_Excludes[$x]}
for (( n = 0 ; n < ${_ebg_len} ; n++ ))
do
[ $# -eq 3 ] && _ebg_x=${_ebg_x}'*' # Do prefix edit
if [ ${_ebg_Target[$n]:=} ] #+ if defined & set.
then
_ebg_t=${_ebg_Target[$n]/#${_ebg_x}/}
[ ${#_ebg_t} -eq 0 ] && unset _ebg_Target[$n]
fi
done
done
eval $2=\( \$\{_ebg_Target\[@\]\} \)
set +f
return 0
}
# This function described in unique_lines.bash.
# unique_lines <in_name&gt; <out_name&gt;
unique_lines() {
[ $# -eq 2 ] || return 1
local -a _ul_in
local -a _ul_out
local -i _ul_cnt
local -i _ul_pos
local _ul_tmp
local IFS=${NO_WSP}
set -f
eval _ul_in=\( \$\{$1\[@\]\} \)
_ul_cnt=${#_ul_in[@]}
for (( _ul_pos = 0 ; _ul_pos < ${_ul_cnt} ; _ul_pos++ ))
do
if [ ${_ul_in[${_ul_pos}]:=} ] # If defined & not empty
then
_ul_tmp=${_ul_in[${_ul_pos}]}
_ul_out[${#_ul_out[@]}]=${_ul_tmp}
for (( zap = _ul_pos ; zap < ${_ul_cnt} ; zap++ ))
do
[ ${_ul_in[${zap}]:=} ] &&
[ 'x'${_ul_in[${zap}]} == 'x'${_ul_tmp} ] &&
unset _ul_in[${zap}]
done
fi
done
eval $2=\( \$\{_ul_out\[@\]\} \)
set +f
return 0
}
# This function described in char_convert.bash.
# to_lower <string&gt;
to_lower() {
[ $# -eq 1 ] || return 1
local _tl_out
_tl_out=${1//A/a}
_tl_out=${_tl_out//B/b}
_tl_out=${_tl_out//C/c}
_tl_out=${_tl_out//D/d}
_tl_out=${_tl_out//E/e}
_tl_out=${_tl_out//F/f}
_tl_out=${_tl_out//G/g}
_tl_out=${_tl_out//H/h}
_tl_out=${_tl_out//I/i}
_tl_out=${_tl_out//J/j}
_tl_out=${_tl_out//K/k}
_tl_out=${_tl_out//L/l}
_tl_out=${_tl_out//M/m}
_tl_out=${_tl_out//N/n}
_tl_out=${_tl_out//O/o}
_tl_out=${_tl_out//P/p}
_tl_out=${_tl_out//Q/q}
_tl_out=${_tl_out//R/r}
_tl_out=${_tl_out//S/s}
_tl_out=${_tl_out//T/t}
_tl_out=${_tl_out//U/u}
_tl_out=${_tl_out//V/v}
_tl_out=${_tl_out//W/w}
_tl_out=${_tl_out//X/x}
_tl_out=${_tl_out//Y/y}
_tl_out=${_tl_out//Z/z}
echo ${_tl_out}
return 0
}
#### Application helper functions ####
# Not everybody uses dots as separators (APNIC, for example).
# This function described in to_dot.bash
# to_dot <string&gt;
to_dot() {
[ $# -eq 1 ] || return 1
echo ${1//[#|@|%]/.}
return 0
}
# This function described in is_number.bash.
# is_number <input&gt;
is_number() {
[ "$#" -eq 1 ] || return 1 # is blank?
[ x"$1" == 'x0' ] && return 0 # is zero?
local -i tst
let tst=$1 2&gt;/dev/null # else is numeric!
return $?
}
# This function described in is_address.bash.
# is_address <input&gt;
is_address() {
[ $# -eq 1 ] || return 1 # Blank ==&gt; false
local -a _ia_input
local IFS=${ADR_IFS}
_ia_input=( $1 )
if [ ${#_ia_input[@]} -eq 4 ] &&
is_number ${_ia_input[0]} &&
is_number ${_ia_input[1]} &&
is_number ${_ia_input[2]} &&
is_number ${_ia_input[3]} &&
[ ${_ia_input[0]} -lt 256 ] &&
[ ${_ia_input[1]} -lt 256 ] &&
[ ${_ia_input[2]} -lt 256 ] &&
[ ${_ia_input[3]} -lt 256 ]
then
return 0
else
return 1
fi
}
# This function described in split_ip.bash.
# split_ip <IP_address&gt;
#+ <array_name_norm&gt; [<array_name_rev&gt;]
split_ip() {
[ $# -eq 3 ] || # Either three
[ $# -eq 2 ] || return 1 #+ or two arguments
local -a _si_input
local IFS=${ADR_IFS}
_si_input=( $1 )
IFS=${WSP_IFS}
eval $2=\(\ \$\{_si_input\[@\]\}\ \)
if [ $# -eq 3 ]
then
# Build query order array.
local -a _dns_ip
_dns_ip[0]=${_si_input[3]}
_dns_ip[1]=${_si_input[2]}
_dns_ip[2]=${_si_input[1]}
_dns_ip[3]=${_si_input[0]}
eval $3=\(\ \$\{_dns_ip\[@\]\}\ \)
fi
return 0
}
# This function described in dot_array.bash.
# dot_array <array_name&gt;
dot_array() {
[ $# -eq 1 ] || return 1 # Single argument required.
local -a _da_input
eval _da_input=\(\ \$\{$1\[@\]\}\ \)
local IFS=${DOT_IFS}
local _da_output=${_da_input[@]}
IFS=${WSP_IFS}
echo ${_da_output}
return 0
}
# This function described in file_to_array.bash
# file_to_array <file_name&gt; <line_array_name&gt;
file_to_array() {
[ $# -eq 2 ] || return 1 # Two arguments required.
local IFS=${NO_WSP}
local -a _fta_tmp_
_fta_tmp_=( $(cat $1) )
eval $2=\( \$\{_fta_tmp_\[@\]\} \)
return 0
}
# Columnized print of an array of multi-field strings.
# col_print <array_name&gt; <min_space&gt; <
#+ tab_stop [tab_stops]&gt;
col_print() {
[ $# -gt 2 ] || return 0
local -a _cp_inp
local -a _cp_spc
local -a _cp_line
local _cp_min
local _cp_mcnt
local _cp_pos
local _cp_cnt
local _cp_tab
local -i _cp
local -i _cpf
local _cp_fld
# WARNING: FOLLOWING LINE NOT BLANK -- IT IS QUOTED SPACES.
local _cp_max=' '
set -f
local IFS=${NO_WSP}
eval _cp_inp=\(\ \$\{$1\[@\]\}\ \)
[ ${#_cp_inp[@]} -gt 0 ] || return 0 # Empty is easy.
_cp_mcnt=$2
_cp_min=${_cp_max:1:${_cp_mcnt}}
shift
shift
_cp_cnt=$#
for (( _cp = 0 ; _cp < _cp_cnt ; _cp++ ))
do
_cp_spc[${#_cp_spc[@]}]="${_cp_max:2:$1}" #"
shift
done
_cp_cnt=${#_cp_inp[@]}
for (( _cp = 0 ; _cp < _cp_cnt ; _cp++ ))
do
_cp_pos=1
IFS=${NO_WSP}$'\x20'
_cp_line=( ${_cp_inp[${_cp}]} )
IFS=${NO_WSP}
for (( _cpf = 0 ; _cpf < ${#_cp_line[@]} ; _cpf++ ))
do
_cp_tab=${_cp_spc[${_cpf}]:${_cp_pos}}
if [ ${#_cp_tab} -lt ${_cp_mcnt} ]
then
_cp_tab="${_cp_min}"
fi
echo -n "${_cp_tab}"
(( _cp_pos = ${_cp_pos} + ${#_cp_tab} ))
_cp_fld="${_cp_line[${_cpf}]}"
echo -n ${_cp_fld}
(( _cp_pos = ${_cp_pos} + ${#_cp_fld} ))
done
echo
done
set +f
return 0
}
# # # # 'Hunt the Spammer' data flow # # # #
# Application return code
declare -i _hs_RC
# Original input, from which IP addresses are removed
# After which, domain names to check
declare -a uc_name
# Original input IP addresses are moved here
# After which, IP addresses to check
declare -a uc_address
# Names against which address expansion run
# Ready for name detail lookup
declare -a chk_name
# Addresses against which name expansion run
# Ready for address detail lookup
declare -a chk_address
# Recursion is depth-first-by-name.
# The expand_input_address maintains this list
#+ to prohibit looking up addresses twice during
#+ domain name recursion.
declare -a been_there_addr
been_there_addr=( '127.0.0.1' ) # Whitelist localhost
# Names which we have checked (or given up on)
declare -a known_name
# Addresses which we have checked (or given up on)
declare -a known_address
# List of zero or more Blacklist servers to check.
# Each 'known_address' will be checked against each server,
#+ with negative replies and failures suppressed.
declare -a list_server
# Indirection limit - set to zero == no limit
indirect=${SPAMMER_LIMIT:=2}
# # # # 'Hunt the Spammer' information output data # # # #
# Any domain name may have multiple IP addresses.
# Any IP address may have multiple domain names.
# Therefore, track unique address-name pairs.
declare -a known_pair
declare -a reverse_pair
# In addition to the data flow variables; known_address
#+ known_name and list_server, the following are output to the
#+ external graphics interface file.
# Authority chain, parent -&gt; SOA fields.
declare -a auth_chain
# Reference chain, parent name -&gt; child name
declare -a ref_chain
# DNS chain - domain name -&gt; address
declare -a name_address
# Name and service pairs - domain name -&gt; service
declare -a name_srvc
# Name and resource pairs - domain name -&gt; Resource Record
declare -a name_resource
# Parent and Child pairs - parent name -&gt; child name
# This MAY NOT be the same as the ref_chain followed!
declare -a parent_child
# Address and Blacklist hit pairs - address-&gt;server
declare -a address_hits
# Dump interface file data
declare -f _dot_dump
_dot_dump=pend_dummy # Initially a no-op
# Data dump is enabled by setting the environment variable SPAMMER_DATA
#+ to the name of a writable file.
declare _dot_file
# Helper function for the dump-to-dot-file function
# dump_to_dot <array_name&gt; <prefix&gt;
dump_to_dot() {
local -a _dda_tmp
local -i _dda_cnt
local _dda_form=' '${2}'%04u %s\n'
local IFS=${NO_WSP}
eval _dda_tmp=\(\ \$\{$1\[@\]\}\ \)
_dda_cnt=${#_dda_tmp[@]}
if [ ${_dda_cnt} -gt 0 ]
then
for (( _dda = 0 ; _dda < _dda_cnt ; _dda++ ))
do
printf "${_dda_form}" \
"${_dda}" "${_dda_tmp[${_dda}]}" &gt;&gt;${_dot_file}
done
fi
}
# Which will also set _dot_dump to this function . . .
dump_dot() {
local -i _dd_cnt
echo '# Data vintage: '$(date -R) &gt;${_dot_file}
echo '# ABS Guide: is_spammer.bash; v2, 2004-msz' &gt;&gt;${_dot_file}
echo &gt;&gt;${_dot_file}
echo 'digraph G {' &gt;&gt;${_dot_file}
if [ ${#known_name[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known domain name nodes' &gt;&gt;${_dot_file}
_dd_cnt=${#known_name[@]}
for (( _dd = 0 ; _dd < _dd_cnt ; _dd++ ))
do
printf ' N%04u [label="%s"] ;\n' \
"${_dd}" "${known_name[${_dd}]}" &gt;&gt;${_dot_file}
done
fi
if [ ${#known_address[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known address nodes' &gt;&gt;${_dot_file}
_dd_cnt=${#known_address[@]}
for (( _dd = 0 ; _dd < _dd_cnt ; _dd++ ))
do
printf ' A%04u [label="%s"] ;\n' \
"${_dd}" "${known_address[${_dd}]}" &gt;&gt;${_dot_file}
done
fi
echo &gt;&gt;${_dot_file}
echo '/*' &gt;&gt;${_dot_file}
echo ' * Known relationships :: User conversion to' &gt;&gt;${_dot_file}
echo ' * graphic form by hand or program required.' &gt;&gt;${_dot_file}
echo ' *' &gt;&gt;${_dot_file}
if [ ${#auth_chain[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Authority ref. edges followed & field source.' &gt;&gt;${_dot_file}
dump_to_dot auth_chain AC
fi
if [ ${#ref_chain[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Name ref. edges followed and field source.' &gt;&gt;${_dot_file}
dump_to_dot ref_chain RC
fi
if [ ${#name_address[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known name-&gt;address edges' &gt;&gt;${_dot_file}
dump_to_dot name_address NA
fi
if [ ${#name_srvc[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known name-&gt;service edges' &gt;&gt;${_dot_file}
dump_to_dot name_srvc NS
fi
if [ ${#name_resource[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known name-&gt;resource edges' &gt;&gt;${_dot_file}
dump_to_dot name_resource NR
fi
if [ ${#parent_child[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known parent-&gt;child edges' &gt;&gt;${_dot_file}
dump_to_dot parent_child PC
fi
if [ ${#list_server[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known Blacklist nodes' &gt;&gt;${_dot_file}
_dd_cnt=${#list_server[@]}
for (( _dd = 0 ; _dd < _dd_cnt ; _dd++ ))
do
printf ' LS%04u [label="%s"] ;\n' \
"${_dd}" "${list_server[${_dd}]}" &gt;&gt;${_dot_file}
done
fi
unique_lines address_hits address_hits
if [ ${#address_hits[@]} -gt 0 ]
then
echo &gt;&gt;${_dot_file}
echo '# Known address-&gt;Blacklist_hit edges' &gt;&gt;${_dot_file}
echo '# CAUTION: dig warnings can trigger false hits.' &gt;&gt;${_dot_file}
dump_to_dot address_hits AH
fi
echo &gt;&gt;${_dot_file}
echo ' *' &gt;&gt;${_dot_file}
echo ' * That is a lot of relationships. Happy graphing.' &gt;&gt;${_dot_file}
echo ' */' &gt;&gt;${_dot_file}
echo '}' &gt;&gt;${_dot_file}
return 0
}
# # # # 'Hunt the Spammer' execution flow # # # #
# Execution trace is enabled by setting the
#+ environment variable SPAMMER_TRACE to the name of a writable file.
declare -a _trace_log
declare _log_file
# Function to fill the trace log
trace_logger() {
_trace_log[${#_trace_log[@]}]=${_pend_current_}
}
# Dump trace log to file function variable.
declare -f _log_dump
_log_dump=pend_dummy # Initially a no-op.
# Dump the trace log to a file.
dump_log() {
local -i _dl_cnt
_dl_cnt=${#_trace_log[@]}
for (( _dl = 0 ; _dl < _dl_cnt ; _dl++ ))
do
echo ${_trace_log[${_dl}]} &gt;&gt; ${_log_file}
done
_dl_cnt=${#_pending_[@]}
if [ ${_dl_cnt} -gt 0 ]
then
_dl_cnt=${_dl_cnt}-1
echo '# # # Operations stack not empty # # #' &gt;&gt; ${_log_file}
for (( _dl = ${_dl_cnt} ; _dl &gt;= 0 ; _dl-- ))
do
echo ${_pending_[${_dl}]} &gt;&gt; ${_log_file}
done
fi
}
# # # Utility program 'dig' wrappers # # #
#
# These wrappers are derived from the
#+ examples shown in dig_wrappers.bash.
#
# The major difference is these return
#+ their results as a list in an array.
#
# See dig_wrappers.bash for details and
#+ use that script to develop any changes.
#
# # #
# Short form answer: 'dig' parses answer.
# Forward lookup :: Name -&gt; Address
# short_fwd <domain_name&gt; <array_name&gt;
short_fwd() {
local -a _sf_reply
local -i _sf_rc
local -i _sf_cnt
IFS=${NO_WSP}
echo -n '.'
# echo 'sfwd: '${1}
_sf_reply=( $(dig +short ${1} -c in -t a 2&gt;/dev/null) )
_sf_rc=$?
if [ ${_sf_rc} -ne 0 ]
then
_trace_log[${#_trace_log[@]}]='## Lookup error '${_sf_rc}' on '${1}' ##'
# [ ${_sf_rc} -ne 9 ] && pend_drop
return ${_sf_rc}
else
# Some versions of 'dig' return warnings on stdout.
_sf_cnt=${#_sf_reply[@]}
for (( _sf = 0 ; _sf < ${_sf_cnt} ; _sf++ ))
do
[ 'x'${_sf_reply[${_sf}]:0:2} == 'x;;' ] &&
unset _sf_reply[${_sf}]
done
eval $2=\( \$\{_sf_reply\[@\]\} \)
fi
return 0
}
# Reverse lookup :: Address -&gt; Name
# short_rev <ip_address&gt; <array_name&gt;
short_rev() {
local -a _sr_reply
local -i _sr_rc
local -i _sr_cnt
IFS=${NO_WSP}
echo -n '.'
# echo 'srev: '${1}
_sr_reply=( $(dig +short -x ${1} 2&gt;/dev/null) )
_sr_rc=$?
if [ ${_sr_rc} -ne 0 ]
then
_trace_log[${#_trace_log[@]}]='## Lookup error '${_sr_rc}' on '${1}' ##'
# [ ${_sr_rc} -ne 9 ] && pend_drop
return ${_sr_rc}
else
# Some versions of 'dig' return warnings on stdout.
_sr_cnt=${#_sr_reply[@]}
for (( _sr = 0 ; _sr < ${_sr_cnt} ; _sr++ ))
do
[ 'x'${_sr_reply[${_sr}]:0:2} == 'x;;' ] &&
unset _sr_reply[${_sr}]
done
eval $2=\( \$\{_sr_reply\[@\]\} \)
fi
return 0
}
# Special format lookup used to query blacklist servers.
# short_text <ip_address&gt; <array_name&gt;
short_text() {
local -a _st_reply
local -i _st_rc
local -i _st_cnt
IFS=${NO_WSP}
# echo 'stxt: '${1}
_st_reply=( $(dig +short ${1} -c in -t txt 2&gt;/dev/null) )
_st_rc=$?
if [ ${_st_rc} -ne 0 ]
then
_trace_log[${#_trace_log[@]}]='##Text lookup error '${_st_rc}' on '${1}'##'
# [ ${_st_rc} -ne 9 ] && pend_drop
return ${_st_rc}
else
# Some versions of 'dig' return warnings on stdout.
_st_cnt=${#_st_reply[@]}
for (( _st = 0 ; _st < ${#_st_cnt} ; _st++ ))
do
[ 'x'${_st_reply[${_st}]:0:2} == 'x;;' ] &&
unset _st_reply[${_st}]
done
eval $2=\( \$\{_st_reply\[@\]\} \)
fi
return 0
}
# The long forms, a.k.a., the parse it yourself versions
# RFC 2782 Service lookups
# dig +noall +nofail +answer _ldap._tcp.openldap.org -t srv
# _<service&gt;._<protocol&gt;.<domain_name&gt;
# _ldap._tcp.openldap.org. 3600 IN SRV 0 0 389 ldap.openldap.org.
# domain TTL Class SRV Priority Weight Port Target
# Forward lookup :: Name -&gt; poor man's zone transfer
# long_fwd <domain_name&gt; <array_name&gt;
long_fwd() {
local -a _lf_reply
local -i _lf_rc
local -i _lf_cnt
IFS=${NO_WSP}
echo -n ':'
# echo 'lfwd: '${1}
_lf_reply=( $(
dig +noall +nofail +answer +authority +additional \
${1} -t soa ${1} -t mx ${1} -t any 2&gt;/dev/null) )
_lf_rc=$?
if [ ${_lf_rc} -ne 0 ]
then
_trace_log[${#_trace_log[@]}]='# Zone lookup err '${_lf_rc}' on '${1}' #'
# [ ${_lf_rc} -ne 9 ] && pend_drop
return ${_lf_rc}
else
# Some versions of 'dig' return warnings on stdout.
_lf_cnt=${#_lf_reply[@]}
for (( _lf = 0 ; _lf < ${_lf_cnt} ; _lf++ ))
do
[ 'x'${_lf_reply[${_lf}]:0:2} == 'x;;' ] &&
unset _lf_reply[${_lf}]
done
eval $2=\( \$\{_lf_reply\[@\]\} \)
fi
return 0
}
# The reverse lookup domain name corresponding to the IPv6 address:
# 4321:0:1:2:3:4:567:89ab
# would be (nibble, I.E: Hexdigit) reversed:
# b.a.9.8.7.6.5.0.4.0.0.0.3.0.0.0.2.0.0.0.1.0.0.0.0.0.0.0.1.2.3.4.IP6.ARPA.
# Reverse lookup :: Address -&gt; poor man's delegation chain
# long_rev <rev_ip_address&gt; <array_name&gt;
long_rev() {
local -a _lr_reply
local -i _lr_rc
local -i _lr_cnt
local _lr_dns
_lr_dns=${1}'.in-addr.arpa.'
IFS=${NO_WSP}
echo -n ':'
# echo 'lrev: '${1}
_lr_reply=( $(
dig +noall +nofail +answer +authority +additional \
${_lr_dns} -t soa ${_lr_dns} -t any 2&gt;/dev/null) )
_lr_rc=$?
if [ ${_lr_rc} -ne 0 ]
then
_trace_log[${#_trace_log[@]}]='# Deleg lkp error '${_lr_rc}' on '${1}' #'
# [ ${_lr_rc} -ne 9 ] && pend_drop
return ${_lr_rc}
else
# Some versions of 'dig' return warnings on stdout.
_lr_cnt=${#_lr_reply[@]}
for (( _lr = 0 ; _lr < ${_lr_cnt} ; _lr++ ))
do
[ 'x'${_lr_reply[${_lr}]:0:2} == 'x;;' ] &&
unset _lr_reply[${_lr}]
done
eval $2=\( \$\{_lr_reply\[@\]\} \)
fi
return 0
}
# # # Application specific functions # # #
# Mung a possible name; suppresses root and TLDs.
# name_fixup <string&gt;
name_fixup(){
local -a _nf_tmp
local -i _nf_end
local _nf_str
local IFS
_nf_str=$(to_lower ${1})
_nf_str=$(to_dot ${_nf_str})
_nf_end=${#_nf_str}-1
[ ${_nf_str:${_nf_end}} != '.' ] &&
_nf_str=${_nf_str}'.'
IFS=${ADR_IFS}
_nf_tmp=( ${_nf_str} )
IFS=${WSP_IFS}
_nf_end=${#_nf_tmp[@]}
case ${_nf_end} in
0) # No dots, only dots.
echo
return 1
;;
1) # Only a TLD.
echo
return 1
;;
2) # Maybe okay.
echo ${_nf_str}
return 0
# Needs a lookup table?
if [ ${#_nf_tmp[1]} -eq 2 ]
then # Country coded TLD.
echo
return 1
else
echo ${_nf_str}
return 0
fi
;;
esac
echo ${_nf_str}
return 0
}
# Grope and mung original input(s).
split_input() {
[ ${#uc_name[@]} -gt 0 ] || return 0
local -i _si_cnt
local -i _si_len
local _si_str
unique_lines uc_name uc_name
_si_cnt=${#uc_name[@]}
for (( _si = 0 ; _si < _si_cnt ; _si++ ))
do
_si_str=${uc_name[$_si]}
if is_address ${_si_str}
then
uc_address[${#uc_address[@]}]=${_si_str}
unset uc_name[$_si]
else
if ! uc_name[$_si]=$(name_fixup ${_si_str})
then
unset ucname[$_si]
fi
fi
done
uc_name=( ${uc_name[@]} )
_si_cnt=${#uc_name[@]}
_trace_log[${#_trace_log[@]}]='#Input '${_si_cnt}' unchkd name input(s).#'
_si_cnt=${#uc_address[@]}
_trace_log[${#_trace_log[@]}]='#Input '${_si_cnt}' unchkd addr input(s).#'
return 0
}
# # # Discovery functions -- recursively interlocked by external data # # #
# # # The leading 'if list is empty; return 0' in each is required. # # #
# Recursion limiter
# limit_chk() <next_level&gt;
limit_chk() {
local -i _lc_lmt
# Check indirection limit.
if [ ${indirect} -eq 0 ] || [ $# -eq 0 ]
then
# The 'do-forever' choice
echo 1 # Any value will do.
return 0 # OK to continue.
else
# Limiting is in effect.
if [ ${indirect} -lt ${1} ]
then
echo ${1} # Whatever.
return 1 # Stop here.
else
_lc_lmt=${1}+1 # Bump the given limit.
echo ${_lc_lmt} # Echo it.
return 0 # OK to continue.
fi
fi
}
# For each name in uc_name:
# Move name to chk_name.
# Add addresses to uc_address.
# Pend expand_input_address.
# Repeat until nothing new found.
# expand_input_name <indirection_limit&gt;
expand_input_name() {
[ ${#uc_name[@]} -gt 0 ] || return 0
local -a _ein_addr
local -a _ein_new
local -i _ucn_cnt
local -i _ein_cnt
local _ein_tst
_ucn_cnt=${#uc_name[@]}
if ! _ein_cnt=$(limit_chk ${1})
then
return 0
fi
for (( _ein = 0 ; _ein < _ucn_cnt ; _ein++ ))
do
if short_fwd ${uc_name[${_ein}]} _ein_new
then
for (( _ein_cnt = 0 ; _ein_cnt < ${#_ein_new[@]}; _ein_cnt++ ))
do
_ein_tst=${_ein_new[${_ein_cnt}]}
if is_address ${_ein_tst}
then
_ein_addr[${#_ein_addr[@]}]=${_ein_tst}
fi
done
fi
done
unique_lines _ein_addr _ein_addr # Scrub duplicates.
edit_exact chk_address _ein_addr # Scrub pending detail.
edit_exact known_address _ein_addr # Scrub already detailed.
if [ ${#_ein_addr[@]} -gt 0 ] # Anything new?
then
uc_address=( ${uc_address[@]} ${_ein_addr[@]} )
pend_func expand_input_address ${1}
_trace_log[${#_trace_log[@]}]='#Add '${#_ein_addr[@]}' unchkd addr inp.#'
fi
edit_exact chk_name uc_name # Scrub pending detail.
edit_exact known_name uc_name # Scrub already detailed.
if [ ${#uc_name[@]} -gt 0 ]
then
chk_name=( ${chk_name[@]} ${uc_name[@]} )
pend_func detail_each_name ${1}
fi
unset uc_name[@]
return 0
}
# For each address in uc_address:
# Move address to chk_address.
# Add names to uc_name.
# Pend expand_input_name.
# Repeat until nothing new found.
# expand_input_address <indirection_limit&gt;
expand_input_address() {
[ ${#uc_address[@]} -gt 0 ] || return 0
local -a _eia_addr
local -a _eia_name
local -a _eia_new
local -i _uca_cnt
local -i _eia_cnt
local _eia_tst
unique_lines uc_address _eia_addr
unset uc_address[@]
edit_exact been_there_addr _eia_addr
_uca_cnt=${#_eia_addr[@]}
[ ${_uca_cnt} -gt 0 ] &&
been_there_addr=( ${been_there_addr[@]} ${_eia_addr[@]} )
for (( _eia = 0 ; _eia < _uca_cnt ; _eia++ ))
do
if short_rev ${_eia_addr[${_eia}]} _eia_new
then
for (( _eia_cnt = 0 ; _eia_cnt < ${#_eia_new[@]} ; _eia_cnt++ ))
do
_eia_tst=${_eia_new[${_eia_cnt}]}
if _eia_tst=$(name_fixup ${_eia_tst})
then
_eia_name[${#_eia_name[@]}]=${_eia_tst}
fi
done
fi
done
unique_lines _eia_name _eia_name # Scrub duplicates.
edit_exact chk_name _eia_name # Scrub pending detail.
edit_exact known_name _eia_name # Scrub already detailed.
if [ ${#_eia_name[@]} -gt 0 ] # Anything new?
then
uc_name=( ${uc_name[@]} ${_eia_name[@]} )
pend_func expand_input_name ${1}
_trace_log[${#_trace_log[@]}]='#Add '${#_eia_name[@]}' unchkd name inp.#'
fi
edit_exact chk_address _eia_addr # Scrub pending detail.
edit_exact known_address _eia_addr # Scrub already detailed.
if [ ${#_eia_addr[@]} -gt 0 ] # Anything new?
then
chk_address=( ${chk_address[@]} ${_eia_addr[@]} )
pend_func detail_each_address ${1}
fi
return 0
}
# The parse-it-yourself zone reply.
# The input is the chk_name list.
# detail_each_name <indirection_limit&gt;
detail_each_name() {
[ ${#chk_name[@]} -gt 0 ] || return 0
local -a _den_chk # Names to check
local -a _den_name # Names found here
local -a _den_address # Addresses found here
local -a _den_pair # Pairs found here
local -a _den_rev # Reverse pairs found here
local -a _den_tmp # Line being parsed
local -a _den_auth # SOA contact being parsed
local -a _den_new # The zone reply
local -a _den_pc # Parent-Child gets big fast
local -a _den_ref # So does reference chain
local -a _den_nr # Name-Resource can be big
local -a _den_na # Name-Address
local -a _den_ns # Name-Service
local -a _den_achn # Chain of Authority
local -i _den_cnt # Count of names to detail
local -i _den_lmt # Indirection limit
local _den_who # Named being processed
local _den_rec # Record type being processed
local _den_cont # Contact domain
local _den_str # Fixed up name string
local _den_str2 # Fixed up reverse
local IFS=${WSP_IFS}
# Local, unique copy of names to check
unique_lines chk_name _den_chk
unset chk_name[@] # Done with globals.
# Less any names already known
edit_exact known_name _den_chk
_den_cnt=${#_den_chk[@]}
# If anything left, add to known_name.
[ ${_den_cnt} -gt 0 ] &&
known_name=( ${known_name[@]} ${_den_chk[@]} )
# for the list of (previously) unknown names . . .
for (( _den = 0 ; _den < _den_cnt ; _den++ ))
do
_den_who=${_den_chk[${_den}]}
if long_fwd ${_den_who} _den_new
then
unique_lines _den_new _den_new
if [ ${#_den_new[@]} -eq 0 ]
then
_den_pair[${#_den_pair[@]}]='0.0.0.0 '${_den_who}
fi
# Parse each line in the reply.
for (( _line = 0 ; _line < ${#_den_new[@]} ; _line++ ))
do
IFS=${NO_WSP}$'\x09'$'\x20'
_den_tmp=( ${_den_new[${_line}]} )
IFS=${WSP_IFS}
# If usable record and not a warning message . . .
if [ ${#_den_tmp[@]} -gt 4 ] && [ 'x'${_den_tmp[0]} != 'x;;' ]
then
_den_rec=${_den_tmp[3]}
_den_nr[${#_den_nr[@]}]=${_den_who}' '${_den_rec}
# Begin at RFC1033 (+++)
case ${_den_rec} in
#<name&gt; [<ttl&gt;] [<class&gt;] SOA <origin&gt; <person&gt;
SOA) # Start Of Authority
if _den_str=$(name_fixup ${_den_tmp[0]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_achn[${#_den_achn[@]}]=${_den_who}' '${_den_str}' SOA'
# SOA origin -- domain name of master zone record
if _den_str2=$(name_fixup ${_den_tmp[4]})
then
_den_name[${#_den_name[@]}]=${_den_str2}
_den_achn[${#_den_achn[@]}]=${_den_who}' '${_den_str2}' SOA.O'
fi
# Responsible party e-mail address (possibly bogus).
# Possibility of first.last@domain.name ignored.
set -f
if _den_str2=$(name_fixup ${_den_tmp[5]})
then
IFS=${ADR_IFS}
_den_auth=( ${_den_str2} )
IFS=${WSP_IFS}
if [ ${#_den_auth[@]} -gt 2 ]
then
_den_cont=${_den_auth[1]}
for (( _auth = 2 ; _auth < ${#_den_auth[@]} ; _auth++ ))
do
_den_cont=${_den_cont}'.'${_den_auth[${_auth}]}
done
_den_name[${#_den_name[@]}]=${_den_cont}'.'
_den_achn[${#_den_achn[@]}]=${_den_who}' '${_den_cont}'. SOA.C'
fi
fi
set +f
fi
;;
A) # IP(v4) Address Record
if _den_str=$(name_fixup ${_den_tmp[0]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_pair[${#_den_pair[@]}]=${_den_tmp[4]}' '${_den_str}
_den_na[${#_den_na[@]}]=${_den_str}' '${_den_tmp[4]}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' A'
else
_den_pair[${#_den_pair[@]}]=${_den_tmp[4]}' unknown.domain'
_den_na[${#_den_na[@]}]='unknown.domain '${_den_tmp[4]}
_den_ref[${#_den_ref[@]}]=${_den_who}' unknown.domain A'
fi
_den_address[${#_den_address[@]}]=${_den_tmp[4]}
_den_pc[${#_den_pc[@]}]=${_den_who}' '${_den_tmp[4]}
;;
NS) # Name Server Record
# Domain name being serviced (may be other than current)
if _den_str=$(name_fixup ${_den_tmp[0]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' NS'
# Domain name of service provider
if _den_str2=$(name_fixup ${_den_tmp[4]})
then
_den_name[${#_den_name[@]}]=${_den_str2}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str2}' NSH'
_den_ns[${#_den_ns[@]}]=${_den_str2}' NS'
_den_pc[${#_den_pc[@]}]=${_den_str}' '${_den_str2}
fi
fi
;;
MX) # Mail Server Record
# Domain name being serviced (wildcards not handled here)
if _den_str=$(name_fixup ${_den_tmp[0]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' MX'
fi
# Domain name of service provider
if _den_str=$(name_fixup ${_den_tmp[5]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' MXH'
_den_ns[${#_den_ns[@]}]=${_den_str}' MX'
_den_pc[${#_den_pc[@]}]=${_den_who}' '${_den_str}
fi
;;
PTR) # Reverse address record
# Special name
if _den_str=$(name_fixup ${_den_tmp[0]})
then
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' PTR'
# Host name (not a CNAME)
if _den_str2=$(name_fixup ${_den_tmp[4]})
then
_den_rev[${#_den_rev[@]}]=${_den_str}' '${_den_str2}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str2}' PTRH'
_den_pc[${#_den_pc[@]}]=${_den_who}' '${_den_str}
fi
fi
;;
AAAA) # IP(v6) Address Record
if _den_str=$(name_fixup ${_den_tmp[0]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_pair[${#_den_pair[@]}]=${_den_tmp[4]}' '${_den_str}
_den_na[${#_den_na[@]}]=${_den_str}' '${_den_tmp[4]}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' AAAA'
else
_den_pair[${#_den_pair[@]}]=${_den_tmp[4]}' unknown.domain'
_den_na[${#_den_na[@]}]='unknown.domain '${_den_tmp[4]}
_den_ref[${#_den_ref[@]}]=${_den_who}' unknown.domain'
fi
# No processing for IPv6 addresses
_den_pc[${#_den_pc[@]}]=${_den_who}' '${_den_tmp[4]}
;;
CNAME) # Alias name record
# Nickname
if _den_str=$(name_fixup ${_den_tmp[0]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' CNAME'
_den_pc[${#_den_pc[@]}]=${_den_who}' '${_den_str}
fi
# Hostname
if _den_str=$(name_fixup ${_den_tmp[4]})
then
_den_name[${#_den_name[@]}]=${_den_str}
_den_ref[${#_den_ref[@]}]=${_den_who}' '${_den_str}' CHOST'
_den_pc[${#_den_pc[@]}]=${_den_who}' '${_den_str}
fi
;;
# TXT)
# ;;
esac
fi
done
else # Lookup error == 'A' record 'unknown address'
_den_pair[${#_den_pair[@]}]='0.0.0.0 '${_den_who}
fi
done
# Control dot array growth.
unique_lines _den_achn _den_achn # Works best, all the same.
edit_exact auth_chain _den_achn # Works best, unique items.
if [ ${#_den_achn[@]} -gt 0 ]
then
IFS=${NO_WSP}
auth_chain=( ${auth_chain[@]} ${_den_achn[@]} )
IFS=${WSP_IFS}
fi
unique_lines _den_ref _den_ref # Works best, all the same.
edit_exact ref_chain _den_ref # Works best, unique items.
if [ ${#_den_ref[@]} -gt 0 ]
then
IFS=${NO_WSP}
ref_chain=( ${ref_chain[@]} ${_den_ref[@]} )
IFS=${WSP_IFS}
fi
unique_lines _den_na _den_na
edit_exact name_address _den_na
if [ ${#_den_na[@]} -gt 0 ]
then
IFS=${NO_WSP}
name_address=( ${name_address[@]} ${_den_na[@]} )
IFS=${WSP_IFS}
fi
unique_lines _den_ns _den_ns
edit_exact name_srvc _den_ns
if [ ${#_den_ns[@]} -gt 0 ]
then
IFS=${NO_WSP}
name_srvc=( ${name_srvc[@]} ${_den_ns[@]} )
IFS=${WSP_IFS}
fi
unique_lines _den_nr _den_nr
edit_exact name_resource _den_nr
if [ ${#_den_nr[@]} -gt 0 ]
then
IFS=${NO_WSP}
name_resource=( ${name_resource[@]} ${_den_nr[@]} )
IFS=${WSP_IFS}
fi
unique_lines _den_pc _den_pc
edit_exact parent_child _den_pc
if [ ${#_den_pc[@]} -gt 0 ]
then
IFS=${NO_WSP}
parent_child=( ${parent_child[@]} ${_den_pc[@]} )
IFS=${WSP_IFS}
fi
# Update list known_pair (Address and Name).
unique_lines _den_pair _den_pair
edit_exact known_pair _den_pair
if [ ${#_den_pair[@]} -gt 0 ] # Anything new?
then
IFS=${NO_WSP}
known_pair=( ${known_pair[@]} ${_den_pair[@]} )
IFS=${WSP_IFS}
fi
# Update list of reverse pairs.
unique_lines _den_rev _den_rev
edit_exact reverse_pair _den_rev
if [ ${#_den_rev[@]} -gt 0 ] # Anything new?
then
IFS=${NO_WSP}
reverse_pair=( ${reverse_pair[@]} ${_den_rev[@]} )
IFS=${WSP_IFS}
fi
# Check indirection limit -- give up if reached.
if ! _den_lmt=$(limit_chk ${1})
then
return 0
fi
# Execution engine is LIFO. Order of pend operations is important.
# Did we define any new addresses?
unique_lines _den_address _den_address # Scrub duplicates.
edit_exact known_address _den_address # Scrub already processed.
edit_exact un_address _den_address # Scrub already waiting.
if [ ${#_den_address[@]} -gt 0 ] # Anything new?
then
uc_address=( ${uc_address[@]} ${_den_address[@]} )
pend_func expand_input_address ${_den_lmt}
_trace_log[${#_trace_log[@]}]='# Add '${#_den_address[@]}' unchkd addr. #'
fi
# Did we find any new names?
unique_lines _den_name _den_name # Scrub duplicates.
edit_exact known_name _den_name # Scrub already processed.
edit_exact uc_name _den_name # Scrub already waiting.
if [ ${#_den_name[@]} -gt 0 ] # Anything new?
then
uc_name=( ${uc_name[@]} ${_den_name[@]} )
pend_func expand_input_name ${_den_lmt}
_trace_log[${#_trace_log[@]}]='#Added '${#_den_name[@]}' unchkd name#'
fi
return 0
}
# The parse-it-yourself delegation reply
# Input is the chk_address list.
# detail_each_address <indirection_limit&gt;
detail_each_address() {
[ ${#chk_address[@]} -gt 0 ] || return 0
unique_lines chk_address chk_address
edit_exact known_address chk_address
if [ ${#chk_address[@]} -gt 0 ]
then
known_address=( ${known_address[@]} ${chk_address[@]} )
unset chk_address[@]
fi
return 0
}
# # # Application specific output functions # # #
# Pretty print the known pairs.
report_pairs() {
echo
echo 'Known network pairs.'
col_print known_pair 2 5 30
if [ ${#auth_chain[@]} -gt 0 ]
then
echo
echo 'Known chain of authority.'
col_print auth_chain 2 5 30 55
fi
if [ ${#reverse_pair[@]} -gt 0 ]
then
echo
echo 'Known reverse pairs.'
col_print reverse_pair 2 5 55
fi
return 0
}
# Check an address against the list of blacklist servers.
# A good place to capture for GraphViz: address-&gt;status(server(reports))
# check_lists <ip_address&gt;
check_lists() {
[ $# -eq 1 ] || return 1
local -a _cl_fwd_addr
local -a _cl_rev_addr
local -a _cl_reply
local -i _cl_rc
local -i _ls_cnt
local _cl_dns_addr
local _cl_lkup
split_ip ${1} _cl_fwd_addr _cl_rev_addr
_cl_dns_addr=$(dot_array _cl_rev_addr)'.'
_ls_cnt=${#list_server[@]}
echo ' Checking address '${1}
for (( _cl = 0 ; _cl < _ls_cnt ; _cl++ ))
do
_cl_lkup=${_cl_dns_addr}${list_server[${_cl}]}
if short_text ${_cl_lkup} _cl_reply
then
if [ ${#_cl_reply[@]} -gt 0 ]
then
echo ' Records from '${list_server[${_cl}]}
address_hits[${#address_hits[@]}]=${1}' '${list_server[${_cl}]}
_hs_RC=2
for (( _clr = 0 ; _clr < ${#_cl_reply[@]} ; _clr++ ))
do
echo ' '${_cl_reply[${_clr}]}
done
fi
fi
done
return 0
}
# # # The usual application glue # # #
# Who did it?
credits() {
echo
echo 'Advanced Bash Scripting Guide: is_spammer.bash, v2, 2004-msz'
}
# How to use it?
# (See also, "Quickstart" at end of script.)
usage() {
cat <<-'_usage_statement_'
The script is_spammer.bash requires either one or two arguments.
arg 1) May be one of:
a) A domain name
b) An IPv4 address
c) The name of a file with any mix of names
and addresses, one per line.
arg 2) May be one of:
a) A Blacklist server domain name
b) The name of a file with Blacklist server
domain names, one per line.
c) If not present, a default list of (free)
Blacklist servers is used.
d) If a filename of an empty, readable, file
is given,
Blacklist server lookup is disabled.
All script output is written to stdout.
Return codes: 0 -&gt; All OK, 1 -&gt; Script failure,
2 -&gt; Something is Blacklisted.
Requires the external program 'dig' from the 'bind-9'
set of DNS programs. See: http://www.isc.org
The domain name lookup depth limit defaults to 2 levels.
Set the environment variable SPAMMER_LIMIT to change.
SPAMMER_LIMIT=0 means 'unlimited'
Limit may also be set on the command-line.
If arg#1 is an integer, the limit is set to that value
and then the above argument rules are applied.
Setting the environment variable 'SPAMMER_DATA' to a filename
will cause the script to write a GraphViz graphic file.
For the development version;
Setting the environment variable 'SPAMMER_TRACE' to a filename
will cause the execution engine to log a function call trace.
_usage_statement_
}
# The default list of Blacklist servers:
# Many choices, see: http://www.spews.org/lists.html
declare -a default_servers
# See: http://www.spamhaus.org (Conservative, well maintained)
default_servers[0]='sbl-xbl.spamhaus.org'
# See: http://ordb.org (Open mail relays)
default_servers[1]='relays.ordb.org'
# See: http://www.spamcop.net/ (You can report spammers here)
default_servers[2]='bl.spamcop.net'
# See: http://www.spews.org (An 'early detect' system)
default_servers[3]='l2.spews.dnsbl.sorbs.net'
# See: http://www.dnsbl.us.sorbs.net/using.shtml
default_servers[4]='dnsbl.sorbs.net'
# See: http://dsbl.org/usage (Various mail relay lists)
default_servers[5]='list.dsbl.org'
default_servers[6]='multihop.dsbl.org'
default_servers[7]='unconfirmed.dsbl.org'
# User input argument #1
setup_input() {
if [ -e ${1} ] && [ -r ${1} ] # Name of readable file
then
file_to_array ${1} uc_name
echo 'Using filename &gt;'${1}'< as input.'
else
if is_address ${1} # IP address?
then
uc_address=( ${1} )
echo 'Starting with address &gt;'${1}'<'
else # Must be a name.
uc_name=( ${1} )
echo 'Starting with domain name &gt;'${1}'<'
fi
fi
return 0
}
# User input argument #2
setup_servers() {
if [ -e ${1} ] && [ -r ${1} ] # Name of a readable file
then
file_to_array ${1} list_server
echo 'Using filename &gt;'${1}'< as blacklist server list.'
else
list_server=( ${1} )
echo 'Using blacklist server &gt;'${1}'<'
fi
return 0
}
# User environment variable SPAMMER_TRACE
live_log_die() {
if [ ${SPAMMER_TRACE:=} ] # Wants trace log?
then
if [ ! -e ${SPAMMER_TRACE} ]
then
if ! touch ${SPAMMER_TRACE} 2&gt;/dev/null
then
pend_func echo $(printf '%q\n' \
'Unable to create log file &gt;'${SPAMMER_TRACE}'<')
pend_release
exit 1
fi
_log_file=${SPAMMER_TRACE}
_pend_hook_=trace_logger
_log_dump=dump_log
else
if [ ! -w ${SPAMMER_TRACE} ]
then
pend_func echo $(printf '%q\n' \
'Unable to write log file &gt;'${SPAMMER_TRACE}'<')
pend_release
exit 1
fi
_log_file=${SPAMMER_TRACE}
echo '' &gt; ${_log_file}
_pend_hook_=trace_logger
_log_dump=dump_log
fi
fi
return 0
}
# User environment variable SPAMMER_DATA
data_capture() {
if [ ${SPAMMER_DATA:=} ] # Wants a data dump?
then
if [ ! -e ${SPAMMER_DATA} ]
then
if ! touch ${SPAMMER_DATA} 2&gt;/dev/null
then
pend_func echo $(printf '%q]n' \
'Unable to create data output file &gt;'${SPAMMER_DATA}'<')
pend_release
exit 1
fi
_dot_file=${SPAMMER_DATA}
_dot_dump=dump_dot
else
if [ ! -w ${SPAMMER_DATA} ]
then
pend_func echo $(printf '%q\n' \
'Unable to write data output file &gt;'${SPAMMER_DATA}'<')
pend_release
exit 1
fi
_dot_file=${SPAMMER_DATA}
_dot_dump=dump_dot
fi
fi
return 0
}
# Grope user specified arguments.
do_user_args() {
if [ $# -gt 0 ] && is_number $1
then
indirect=$1
shift
fi
case $# in # Did user treat us well?
1)
if ! setup_input $1 # Needs error checking.
then
pend_release
$_log_dump
exit 1
fi
list_server=( ${default_servers[@]} )
_list_cnt=${#list_server[@]}
echo 'Using default blacklist server list.'
echo 'Search depth limit: '${indirect}
;;
2)
if ! setup_input $1 # Needs error checking.
then
pend_release
$_log_dump
exit 1
fi
if ! setup_servers $2 # Needs error checking.
then
pend_release
$_log_dump
exit 1
fi
echo 'Search depth limit: '${indirect}
;;
*)
pend_func usage
pend_release
$_log_dump
exit 1
;;
esac
return 0
}
# A general purpose debug tool.
# list_array <array_name&gt;
list_array() {
[ $# -eq 1 ] || return 1 # One argument required.
local -a _la_lines
set -f
local IFS=${NO_WSP}
eval _la_lines=\(\ \$\{$1\[@\]\}\ \)
echo
echo "Element count "${#_la_lines[@]}" array "${1}
local _ln_cnt=${#_la_lines[@]}
for (( _i = 0; _i < ${_ln_cnt}; _i++ ))
do
echo 'Element '$_i' &gt;'${_la_lines[$_i]}'<'
done
set +f
return 0
}
# # # 'Hunt the Spammer' program code # # #
pend_init # Ready stack engine.
pend_func credits # Last thing to print.
# # # Deal with user # # #
live_log_die # Setup debug trace log.
data_capture # Setup data capture file.
echo
do_user_args $@
# # # Haven't exited yet - There is some hope # # #
# Discovery group - Execution engine is LIFO - pend
# in reverse order of execution.
_hs_RC=0 # Hunt the Spammer return code
pend_mark
pend_func report_pairs # Report name-address pairs.
# The two detail_* are mutually recursive functions.
# They also pend expand_* functions as required.
# These two (the last of ???) exit the recursion.
pend_func detail_each_address # Get all resources of addresses.
pend_func detail_each_name # Get all resources of names.
# The two expand_* are mutually recursive functions,
#+ which pend additional detail_* functions as required.
pend_func expand_input_address 1 # Expand input names by address.
pend_func expand_input_name 1 # #xpand input addresses by name.
# Start with a unique set of names and addresses.
pend_func unique_lines uc_address uc_address
pend_func unique_lines uc_name uc_name
# Separate mixed input of names and addresses.
pend_func split_input
pend_release
# # # Pairs reported -- Unique list of IP addresses found
echo
_ip_cnt=${#known_address[@]}
if [ ${#list_server[@]} -eq 0 ]
then
echo 'Blacklist server list empty, none checked.'
else
if [ ${_ip_cnt} -eq 0 ]
then
echo 'Known address list empty, none checked.'
else
_ip_cnt=${_ip_cnt}-1 # Start at top.
echo 'Checking Blacklist servers.'
for (( _ip = _ip_cnt ; _ip &gt;= 0 ; _ip-- ))
do
pend_func check_lists $( printf '%q\n' ${known_address[$_ip]} )
done
fi
fi
pend_release
$_dot_dump # Graphics file dump
$_log_dump # Execution trace
echo
##############################
# Example output from script #
##############################
:<<-'_is_spammer_outputs_'
./is_spammer.bash 0 web4.alojamentos7.com
Starting with domain name &gt;web4.alojamentos7.com<
Using default blacklist server list.
Search depth limit: 0
.:....::::...:::...:::.......::..::...:::.......::
Known network pairs.
66.98.208.97 web4.alojamentos7.com.
66.98.208.97 ns1.alojamentos7.com.
69.56.202.147 ns2.alojamentos.ws.
66.98.208.97 alojamentos7.com.
66.98.208.97 web.alojamentos7.com.
69.56.202.146 ns1.alojamentos.ws.
69.56.202.146 alojamentos.ws.
66.235.180.113 ns1.alojamentos.org.
66.235.181.192 ns2.alojamentos.org.
66.235.180.113 alojamentos.org.
66.235.180.113 web6.alojamentos.org.
216.234.234.30 ns1.theplanet.com.
12.96.160.115 ns2.theplanet.com.
216.185.111.52 mail1.theplanet.com.
69.56.141.4 spooling.theplanet.com.
216.185.111.40 theplanet.com.
216.185.111.40 www.theplanet.com.
216.185.111.52 mail.theplanet.com.
Checking Blacklist servers.
Checking address 66.98.208.97
Records from dnsbl.sorbs.net
"Spam Received See: http://www.dnsbl.sorbs.net/lookup.shtml?66.98.208.97"
Checking address 69.56.202.147
Checking address 69.56.202.146
Checking address 66.235.180.113
Checking address 66.235.181.192
Checking address 216.185.111.40
Checking address 216.234.234.30
Checking address 12.96.160.115
Checking address 216.185.111.52
Checking address 69.56.141.4
Advanced Bash Scripting Guide: is_spammer.bash, v2, 2004-msz
_is_spammer_outputs_
exit ${_hs_RC}
####################################################
# The script ignores everything from here on down #
#+ because of the 'exit' command, just above. #
####################################################
Quickstart
==========
Prerequisites
Bash version 2.05b or 3.00 (bash --version)
A version of Bash which supports arrays. Array
support is included by default Bash configurations.
'dig,' version 9.x.x (dig $HOSTNAME, see first line of output)
A version of dig which supports the +short options.
See: dig_wrappers.bash for details.
Optional Prerequisites
'named,' a local DNS caching program. Any flavor will do.
Do twice: dig $HOSTNAME
Check near bottom of output for: SERVER: 127.0.0.1#53
That means you have one running.
Optional Graphics Support
'date,' a standard *nix thing. (date -R)
dot Program to convert graphic description file to a
diagram. (dot -V)
A part of the Graph-Viz set of programs.
See: [http://www.research.att.com/sw/tools/graphviz||GraphViz]
'dotty,' a visual editor for graphic description files.
Also a part of the Graph-Viz set of programs.
Quick Start
In the same directory as the is_spammer.bash script;
Do: ./is_spammer.bash
Usage Details
1. Blacklist server choices.
(a) To use default, built-in list: Do nothing.
(b) To use your own list:
i. Create a file with a single Blacklist server
domain name per line.
ii. Provide that filename as the last argument to
the script.
(c) To use a single Blacklist server: Last argument
to the script.
(d) To disable Blacklist lookups:
i. Create an empty file (touch spammer.nul)
Your choice of filename.
ii. Provide the filename of that empty file as the
last argument to the script.
2. Search depth limit.
(a) To use the default value of 2: Do nothing.
(b) To set a different limit:
A limit of 0 means: no limit.
i. export SPAMMER_LIMIT=1
or whatever limit you want.
ii. OR provide the desired limit as the first
argument to the script.
3. Optional execution trace log.
(a) To use the default setting of no log output: Do nothing.
(b) To write an execution trace log:
export SPAMMER_TRACE=spammer.log
or whatever filename you want.
4. Optional graphic description file.
(a) To use the default setting of no graphic file: Do nothing.
(b) To write a Graph-Viz graphic description file:
export SPAMMER_DATA=spammer.dot
or whatever filename you want.
5. Where to start the search.
(a) Starting with a single domain name:
i. Without a command-line search limit: First
argument to script.
ii. With a command-line search limit: Second
argument to script.
(b) Starting with a single IP address:
i. Without a command-line search limit: First
argument to script.
ii. With a command-line search limit: Second
argument to script.
(c) Starting with (mixed) multiple name(s) and/or address(es):
Create a file with one name or address per line.
Your choice of filename.
i. Without a command-line search limit: Filename as
first argument to script.
ii. With a command-line search limit: Filename as
second argument to script.
6. What to do with the display output.
(a) To view display output on screen: Do nothing.
(b) To save display output to a file: Redirect stdout to a filename.
(c) To discard display output: Redirect stdout to /dev/null.
7. Temporary end of decision making.
press RETURN
wait (optionally, watch the dots and colons).
8. Optionally check the return code.
(a) Return code 0: All OK
(b) Return code 1: Script setup failure
(c) Return code 2: Something was blacklisted.
9. Where is my graph (diagram)?
The script does not directly produce a graph (diagram).
It only produces a graphic description file. You can
process the graphic descriptor file that was output
with the 'dot' program.
Until you edit that descriptor file, to describe the
relationships you want shown, all that you will get is
a bunch of labeled name and address nodes.
All of the script's discovered relationships are within
a comment block in the graphic descriptor file, each
with a descriptive heading.
The editing required to draw a line between a pair of
nodes from the information in the descriptor file may
be done with a text editor.
Given these lines somewhere in the descriptor file:
# Known domain name nodes
N0000 [label="guardproof.info."] ;
N0002 [label="third.guardproof.info."] ;
# Known address nodes
A0000 [label="61.141.32.197"] ;
/*
# Known name-&gt;address edges
NA0000 third.guardproof.info. 61.141.32.197
# Known parent-&gt;child edges
PC0000 guardproof.info. third.guardproof.info.
*/
Turn that into the following lines by substituting node
identifiers into the relationships:
# Known domain name nodes
N0000 [label="guardproof.info."] ;
N0002 [label="third.guardproof.info."] ;
# Known address nodes
A0000 [label="61.141.32.197"] ;
# PC0000 guardproof.info. third.guardproof.info.
N0000-&gt;N0002 ;
# NA0000 third.guardproof.info. 61.141.32.197
N0002-&gt;A0000 ;
/*
# Known name-&gt;address edges
NA0000 third.guardproof.info. 61.141.32.197
# Known parent-&gt;child edges
PC0000 guardproof.info. third.guardproof.info.
*/
Process that with the 'dot' program, and you have your
first network diagram.
In addition to the conventional graphic edges, the
descriptor file includes similar format pair-data that
describes services, zone records (sub-graphs?),
blacklisted addresses, and other things which might be
interesting to include in your graph. This additional
information could be displayed as different node
shapes, colors, line sizes, etc.
The descriptor file can also be read and edited by a
Bash script (of course). You should be able to find
most of the functions required within the
"is_spammer.bash" script.
# End Quickstart.
Additional Note
========== ====
Michael Zick points out that there is a "makeviz.bash" interactive
Web site at rediris.es. Can't give the full URL, since this is not
a publically accessible site.
#!/bin/bash
# whx.sh: "whois" spammer lookup
# Author: Walter Dnes
# Slight revisions (first section) by ABS Guide author.
# Used in ABS Guide with permission.
# Needs version 3.x or greater of Bash to run (because of =~ operator).
# Commented by script author and ABS Guide author.
E_BADARGS=85 # Missing command-line arg.
E_NOHOST=86 # Host not found.
E_TIMEOUT=87 # Host lookup timed out.
E_UNDEF=88 # Some other (undefined) error.
HOSTWAIT=10 # Specify up to 10 seconds for host query reply.
# The actual wait may be a bit longer.
OUTFILE=whois.txt # Output file.
PORT=4321
if [ -z "$1" ] # Check for (required) command-line arg.
then
echo "Usage: $0 domain name or IP address"
exit $E_BADARGS
fi
if [[ "$1" =~ [a-zA-Z][a-zA-Z]$ ]] # Ends in two alpha chars?
then # It's a domain name &&
#+ must do host lookup.
IPADDR=$(host -W $HOSTWAIT $1 | awk '{print $4}')
# Doing host lookup
#+ to get IP address.
# Extract final field.
else
IPADDR="$1" # Command-line arg was IP address.
fi
echo; echo "IP Address is: "$IPADDR""; echo
if [ -e "$OUTFILE" ]
then
rm -f "$OUTFILE"
echo "Stale output file \"$OUTFILE\" removed."; echo
fi
# Sanity checks.
# (This section needs more work.)
# ===============================
if [ -z "$IPADDR" ]
# No response.
then
echo "Host not found!"
exit $E_NOHOST # Bail out.
fi
if [[ "$IPADDR" =~ ^[;;] ]]
# ;; Connection timed out; no servers could be reached.
then
echo "Host lookup timed out!"
exit $E_TIMEOUT # Bail out.
fi
if [[ "$IPADDR" =~ [(NXDOMAIN)]$ ]]
# Host xxxxxxxxx.xxx not found: 3(NXDOMAIN)
then
echo "Host not found!"
exit $E_NOHOST # Bail out.
fi
if [[ "$IPADDR" =~ [(SERVFAIL)]$ ]]
# Host xxxxxxxxx.xxx not found: 2(SERVFAIL)
then
echo "Host not found!"
exit $E_NOHOST # Bail out.
fi
# ======================== Main body of script ========================
AFRINICquery() {
# Define the function that queries AFRINIC. Echo a notification to the
#+ screen, and then run the actual query, redirecting output to $OUTFILE.
echo "Searching for $IPADDR in whois.afrinic.net"
whois -h whois.afrinic.net "$IPADDR" &gt; $OUTFILE
# Check for presence of reference to an rwhois.
# Warn about non-functional rwhois.infosat.net server
#+ and attempt rwhois query.
if grep -e "^remarks: .*rwhois\.[^ ]\+" "$OUTFILE"
then
echo " " &gt;&gt; $OUTFILE
echo "***" &gt;&gt; $OUTFILE
echo "***" &gt;&gt; $OUTFILE
echo "Warning: rwhois.infosat.net was not working \
as of 2005/02/02" &gt;&gt; $OUTFILE
echo " when this script was written." &gt;&gt; $OUTFILE
echo "***" &gt;&gt; $OUTFILE
echo "***" &gt;&gt; $OUTFILE
echo " " &gt;&gt; $OUTFILE
RWHOIS=`grep "^remarks: .*rwhois\.[^ ]\+" "$OUTFILE" | tail -n 1 |\
sed "s/\(^.*\)\(rwhois\..*\)\(:4.*\)/\2/"`
whois -h ${RWHOIS}:${PORT} "$IPADDR" &gt;&gt; $OUTFILE
fi
}
APNICquery() {
echo "Searching for $IPADDR in whois.apnic.net"
whois -h whois.apnic.net "$IPADDR" &gt; $OUTFILE
# Just about every country has its own internet registrar.
# I don't normally bother consulting them, because the regional registry
#+ usually supplies sufficient information.
# There are a few exceptions, where the regional registry simply
#+ refers to the national registry for direct data.
# These are Japan and South Korea in APNIC, and Brasil in LACNIC.
# The following if statement checks $OUTFILE (whois.txt) for the presence
#+ of "KR" (South Korea) or "JP" (Japan) in the country field.
# If either is found, the query is re-run against the appropriate
#+ national registry.
if grep -E "^country:[ ]+KR$" "$OUTFILE"
then
echo "Searching for $IPADDR in whois.krnic.net"
whois -h whois.krnic.net "$IPADDR" &gt;&gt; $OUTFILE
elif grep -E "^country:[ ]+JP$" "$OUTFILE"
then
echo "Searching for $IPADDR in whois.nic.ad.jp"
whois -h whois.nic.ad.jp "$IPADDR"/e &gt;&gt; $OUTFILE
fi
}
ARINquery() {
echo "Searching for $IPADDR in whois.arin.net"
whois -h whois.arin.net "$IPADDR" &gt; $OUTFILE
# Several large internet providers listed by ARIN have their own
#+ internal whois service, referred to as "rwhois".
# A large block of IP addresses is listed with the provider
#+ under the ARIN registry.
# To get the IP addresses of 2nd-level ISPs or other large customers,
#+ one has to refer to the rwhois server on port 4321.
# I originally started with a bunch of "if" statements checking for
#+ the larger providers.
# This approach is unwieldy, and there's always another rwhois server
#+ that I didn't know about.
# A more elegant approach is to check $OUTFILE for a reference
#+ to a whois server, parse that server name out of the comment section,
#+ and re-run the query against the appropriate rwhois server.
# The parsing looks a bit ugly, with a long continued line inside
#+ backticks.
# But it only has to be done once, and will work as new servers are added.
#@ ABS Guide author comment: it isn't all that ugly, and is, in fact,
#@+ an instructive use of Regular Expressions.
if grep -E "^Comment: .*rwhois.[^ ]+" "$OUTFILE"
then
RWHOIS=`grep -e "^Comment:.*rwhois\.[^ ]\+" "$OUTFILE" | tail -n 1 |\
sed "s/^\(.*\)\(rwhois\.[^ ]\+\)\(.*$\)/\2/"`
echo "Searching for $IPADDR in ${RWHOIS}"
whois -h ${RWHOIS}:${PORT} "$IPADDR" &gt;&gt; $OUTFILE
fi
}
LACNICquery() {
echo "Searching for $IPADDR in whois.lacnic.net"
whois -h whois.lacnic.net "$IPADDR" &gt; $OUTFILE
# The following if statement checks $OUTFILE (whois.txt) for
#+ the presence of "BR" (Brasil) in the country field.
# If it is found, the query is re-run against whois.registro.br.
if grep -E "^country:[ ]+BR$" "$OUTFILE"
then
echo "Searching for $IPADDR in whois.registro.br"
whois -h whois.registro.br "$IPADDR" &gt;&gt; $OUTFILE
fi
}
RIPEquery() {
echo "Searching for $IPADDR in whois.ripe.net"
whois -h whois.ripe.net "$IPADDR" &gt; $OUTFILE
}
# Initialize a few variables.
# * slash8 is the most significant octet
# * slash16 consists of the two most significant octets
# * octet2 is the second most significant octet
slash8=`echo $IPADDR | cut -d. -f 1`
if [ -z "$slash8" ] # Yet another sanity check.
then
echo "Undefined error!"
exit $E_UNDEF
fi
slash16=`echo $IPADDR | cut -d. -f 1-2`
# ^ Period specified as 'cut" delimiter.
if [ -z "$slash16" ]
then
echo "Undefined error!"
exit $E_UNDEF
fi
octet2=`echo $slash16 | cut -d. -f 2`
if [ -z "$octet2" ]
then
echo "Undefined error!"
exit $E_UNDEF
fi
# Check for various odds and ends of reserved space.
# There is no point in querying for those addresses.
if [ $slash8 == 0 ]; then
echo $IPADDR is '"This Network"' space\; Not querying
elif [ $slash8 == 10 ]; then
echo $IPADDR is RFC1918 space\; Not querying
elif [ $slash8 == 14 ]; then
echo $IPADDR is '"Public Data Network"' space\; Not querying
elif [ $slash8 == 127 ]; then
echo $IPADDR is loopback space\; Not querying
elif [ $slash16 == 169.254 ]; then
echo $IPADDR is link-local space\; Not querying
elif [ $slash8 == 172 ] && [ $octet2 -ge 16 ] && [ $octet2 -le 31 ];then
echo $IPADDR is RFC1918 space\; Not querying
elif [ $slash16 == 192.168 ]; then
echo $IPADDR is RFC1918 space\; Not querying
elif [ $slash8 -ge 224 ]; then
echo $IPADDR is either Multicast or reserved space\; Not querying
elif [ $slash8 -ge 200 ] && [ $slash8 -le 201 ]; then LACNICquery "$IPADDR"
elif [ $slash8 -ge 202 ] && [ $slash8 -le 203 ]; then APNICquery "$IPADDR"
elif [ $slash8 -ge 210 ] && [ $slash8 -le 211 ]; then APNICquery "$IPADDR"
elif [ $slash8 -ge 218 ] && [ $slash8 -le 223 ]; then APNICquery "$IPADDR"
# If we got this far without making a decision, query ARIN.
# If a reference is found in $OUTFILE to APNIC, AFRINIC, LACNIC, or RIPE,
#+ query the appropriate whois server.
else
ARINquery "$IPADDR"
if grep "whois.afrinic.net" "$OUTFILE"; then
AFRINICquery "$IPADDR"
elif grep -E "^OrgID:[ ]+RIPE$" "$OUTFILE"; then
RIPEquery "$IPADDR"
elif grep -E "^OrgID:[ ]+APNIC$" "$OUTFILE"; then
APNICquery "$IPADDR"
elif grep -E "^OrgID:[ ]+LACNIC$" "$OUTFILE"; then
LACNICquery "$IPADDR"
fi
fi
#@ ---------------------------------------------------------------
# Try also:
# wget http://logi.cc/nw/whois.php3?ACTION=doQuery&DOMAIN=$IPADDR
#@ ---------------------------------------------------------------
# We've now finished the querying.
# Echo a copy of the final result to the screen.
cat $OUTFILE
# Or "less $OUTFILE" . . .
exit 0
#@ ABS Guide author comments:
#@ Nothing fancy here, but still a very useful tool for hunting spammers.
#@ Sure, the script can be cleaned up some, and it's still a bit buggy,
#@+ (exercise for reader), but all the same, it's a nice piece of coding
#@+ by Walter Dnes.
#@ Thank you!
#!/bin/bash
# wgetter2.bash
# Author: Little Monster [monster@monstruum.co.uk]
# ==&gt; Used in ABS Guide with permission of script author.
# ==&gt; This script still needs debugging and fixups (exercise for reader).
# ==&gt; It could also use some additional editing in the comments.
# This is wgetter2 --
#+ a Bash script to make wget a bit more friendly, and save typing.
# Carefully crafted by Little Monster.
# More or less complete on 02/02/2005.
# If you think this script can be improved,
#+ email me at: monster@monstruum.co.uk
# ==&gt; and cc: to the author of the ABS Guide, please.
# This script is licenced under the GPL.
# You are free to copy, alter and re-use it,
#+ but please don't try to claim you wrote it.
# Log your changes here instead.
# =======================================================================
# changelog:
# 07/02/2005. Fixups by Little Monster.
# 02/02/2005. Minor additions by Little Monster.
# (See after # +++++++++++ )
# 29/01/2005. Minor stylistic edits and cleanups by author of ABS Guide.
# Added exit error codes.
# 22/11/2004. Finished initial version of second version of wgetter:
# wgetter2 is born.
# 01/12/2004. Changed 'runn' function so it can be run 2 ways --
# either ask for a file name or have one input on the CL.
# 01/12/2004. Made sensible handling of no URL's given.
# 01/12/2004. Made loop of main options, so you don't
# have to keep calling wgetter 2 all the time.
# Runs as a session instead.
# 01/12/2004. Added looping to 'runn' function.
# Simplified and improved.
# 01/12/2004. Added state to recursion setting.
# Enables re-use of previous value.
# 05/12/2004. Modified the file detection routine in the 'runn' function
# so it's not fooled by empty values, and is cleaner.
# 01/02/2004. Added cookie finding routine from later version (which
# isn't ready yet), so as not to have hard-coded paths.
# =======================================================================
# Error codes for abnormal exit.
E_USAGE=67 # Usage message, then quit.
E_NO_OPTS=68 # No command-line args entered.
E_NO_URLS=69 # No URLs passed to script.
E_NO_SAVEFILE=70 # No save filename passed to script.
E_USER_EXIT=71 # User decides to quit.
# Basic default wget command we want to use.
# This is the place to change it, if required.
# NB: if using a proxy, set http_proxy = yourproxy in .wgetrc.
# Otherwise delete --proxy=on, below.
# ====================================================================
CommandA="wget -nc -c -t 5 --progress=bar --random-wait --proxy=on -r"
# ====================================================================
# --------------------------------------------------------------------
# Set some other variables and explain them.
pattern=" -A .jpg,.JPG,.jpeg,.JPEG,.gif,.GIF,.htm,.html,.shtml,.php"
# wget's option to only get certain types of file.
# comment out if not using
today=`date +%F` # Used for a filename.
home=$HOME # Set HOME to an internal variable.
# In case some other path is used, change it here.
depthDefault=3 # Set a sensible default recursion.
Depth=$depthDefault # Otherwise user feedback doesn't tie in properly.
RefA="" # Set blank referring page.
Flag="" # Default to not saving anything,
#+ or whatever else might be wanted in future.
lister="" # Used for passing a list of urls directly to wget.
Woptions="" # Used for passing wget some options for itself.
inFile="" # Used for the run function.
newFile="" # Used for the run function.
savePath="$home/w-save"
Config="$home/.wgetter2rc"
# This is where some variables can be stored,
#+ if permanently changed from within the script.
Cookie_List="$home/.cookielist"
# So we know where the cookies are kept . . .
cFlag="" # Part of the cookie file selection routine.
# Define the options available. Easy to change letters here if needed.
# These are the optional options; you don't just wait to be asked.
save=s # Save command instead of executing it.
cook=c # Change cookie file for this session.
help=h # Usage guide.
list=l # Pass wget the -i option and URL list.
runn=r # Run saved commands as an argument to the option.
inpu=i # Run saved commands interactively.
wopt=w # Allow to enter options to pass directly to wget.
# --------------------------------------------------------------------
if [ -z "$1" ]; then # Make sure we get something for wget to eat.
echo "You must at least enter a URL or option!"
echo "-$help for usage."
exit $E_NO_OPTS
fi
# +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# added added added added added added added added added added added added
if [ ! -e "$Config" ]; then # See if configuration file exists.
echo "Creating configuration file, $Config"
echo "# This is the configuration file for wgetter2" &gt; "$Config"
echo "# Your customised settings will be saved in this file" &gt;&gt; "$Config"
else
source $Config # Import variables we set outside the script.
fi
if [ ! -e "$Cookie_List" ]; then
# Set up a list of cookie files, if there isn't one.
echo "Hunting for cookies . . ."
find -name cookies.txt &gt;&gt; $Cookie_List # Create the list of cookie files.
fi # Isolate this in its own 'if' statement,
#+ in case we got interrupted while searching.
if [ -z "$cFlag" ]; then # If we haven't already done this . . .
echo # Make a nice space after the command prompt.
echo "Looks like you haven't set up your source of cookies yet."
n=0 # Make sure the counter
#+ doesn't contain random values.
while read; do
Cookies[$n]=$REPLY # Put the cookie files we found into an array.
echo "$n) ${Cookies[$n]}" # Create a menu.
n=$(( n + 1 )) # Increment the counter.
done < $Cookie_List # Feed the read statement.
echo "Enter the number of the cookie file you want to use."
echo "If you won't be using cookies, just press RETURN."
echo
echo "I won't be asking this again. Edit $Config"
echo "If you decide to change at a later date"
echo "or use the -${cook} option for per session changes."
read
if [ ! -z $REPLY ]; then # User didn't just press return.
Cookie=" --load-cookies ${Cookies[$REPLY]}"
# Set the variable here as well as in the config file.
echo "Cookie=\" --load-cookies ${Cookies[$REPLY]}\"" &gt;&gt; $Config
fi
echo "cFlag=1" &gt;&gt; $Config # So we know not to ask again.
fi
# end added section end added section end added section end added section
# +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# Another variable.
# This one may or may not be subject to variation.
# A bit like the small print.
CookiesON=$Cookie
# echo "cookie file is $CookiesON" # For debugging.
# echo "home is ${home}" # For debugging.
# Got caught with this one!
wopts()
{
echo "Enter options to pass to wget."
echo "It is assumed you know what you're doing."
echo
echo "You can pass their arguments here too."
# That is to say, everything passed here is passed to wget.
read Wopts
# Read in the options to be passed to wget.
Woptions=" $Wopts"
# ^ Why the leading space?
# Assign to another variable.
# Just for fun, or something . . .
echo "passing options ${Wopts} to wget"
# Mainly for debugging.
# Is cute.
return
}
save_func()
{
echo "Settings will be saved."
if [ ! -d $savePath ]; then # See if directory exists.
mkdir $savePath # Create the directory to save things in
#+ if it isn't already there.
fi
Flag=S
# Tell the final bit of code what to do.
# Set a flag since stuff is done in main.
return
}
usage() # Tell them how it works.
{
echo "Welcome to wgetter. This is a front end to wget."
echo "It will always run wget with these options:"
echo "$CommandA"
echo "and the pattern to match: $pattern \
(which you can change at the top of this script)."
echo "It will also ask you for recursion depth, \
and if you want to use a referring page."
echo "Wgetter accepts the following options:"
echo ""
echo "-$help : Display this help."
echo "-$save : Save the command to a file $savePath/wget-($today) \
instead of running it."
echo "-$runn : Run saved wget commands instead of starting a new one -"
echo "Enter filename as argument to this option."
echo "-$inpu : Run saved wget commands interactively --"
echo "The script will ask you for the filename."
echo "-$cook : Change the cookies file for this session."
echo "-$list : Tell wget to use URL's from a list instead of \
from the command-line."
echo "-$wopt : Pass any other options direct to wget."
echo ""
echo "See the wget man page for additional options \
you can pass to wget."
echo ""
exit $E_USAGE # End here. Don't process anything else.
}
list_func() # Gives the user the option to use the -i option to wget,
#+ and a list of URLs.
{
while [ 1 ]; do
echo "Enter the name of the file containing URL's (press q to change
your mind)."
read urlfile
if [ ! -e "$urlfile" ] && [ "$urlfile" != q ]; then
# Look for a file, or the quit option.
echo "That file does not exist!"
elif [ "$urlfile" = q ]; then # Check quit option.
echo "Not using a url list."
return
else
echo "using $urlfile."
echo "If you gave url's on the command-line, I'll use those first."
# Report wget standard behaviour to the user.
lister=" -i $urlfile" # This is what we want to pass to wget.
return
fi
done
}
cookie_func() # Give the user the option to use a different cookie file.
{
while [ 1 ]; do
echo "Change the cookies file. Press return if you don't want to change
it."
read Cookies
# NB: this is not the same as Cookie, earlier.
# There is an 's' on the end.
# Bit like chocolate chips.
if [ -z "$Cookies" ]; then # Escape clause for wusses.
return
elif [ ! -e "$Cookies" ]; then
echo "File does not exist. Try again." # Keep em going . . .
else
CookiesON=" --load-cookies $Cookies" # File is good -- use it!
return
fi
done
}
run_func()
{
if [ -z "$OPTARG" ]; then
# Test to see if we used the in-line option or the query one.
if [ ! -d "$savePath" ]; then # If directory doesn't exist . . .
echo "$savePath does not appear to exist."
echo "Please supply path and filename of saved wget commands:"
read newFile
until [ -f "$newFile" ]; do # Keep going till we get something.
echo "Sorry, that file does not exist. Please try again."
# Try really hard to get something.
read newFile
done
# -----------------------------------------------------------------------
# if [ -z ( grep wget ${newfile} ) ]; then
# Assume they haven't got the right file and bail out.
# echo "Sorry, that file does not contain wget commands. Aborting."
# exit
# fi
#
# This is bogus code.
# It doesn't actually work.
# If anyone wants to fix it, feel free!
# -----------------------------------------------------------------------
filePath="${newFile}"
else
echo "Save path is $savePath"
echo "Please enter name of the file which you want to use."
echo "You have a choice of:"
ls $savePath # Give them a choice.
read inFile
until [ -f "$savePath/$inFile" ]; do # Keep going till
#+ we get something.
if [ ! -f "${savePath}/${inFile}" ]; then # If file doesn't exist.
echo "Sorry, that file does not exist. Please choose from:"
ls $savePath # If a mistake is made.
read inFile
fi
done
filePath="${savePath}/${inFile}" # Make one variable . . .
fi
else filePath="${savePath}/${OPTARG}" # Which can be many things . . .
fi
if [ ! -f "$filePath" ]; then # If a bogus file got through.
echo "You did not specify a suitable file."
echo "Run this script with the -${save} option first."
echo "Aborting."
exit $E_NO_SAVEFILE
fi
echo "Using: $filePath"
while read; do
eval $REPLY
echo "Completed: $REPLY"
done < $filePath # Feed the actual file we are using into a 'while' loop.
exit
}
# Fish out any options we are using for the script.
# This is based on the demo in "Learning The Bash Shell" (O'Reilly).
while getopts ":$save$cook$help$list$runn:$inpu$wopt" opt
do
case $opt in
$save) save_func;; # Save some wgetter sessions for later.
$cook) cookie_func;; # Change cookie file.
$help) usage;; # Get help.
$list) list_func;; # Allow wget to use a list of URLs.
$runn) run_func;; # Useful if you are calling wgetter from,
#+ for example, a cron script.
$inpu) run_func;; # When you don't know what your files are named.
$wopt) wopts;; # Pass options directly to wget.
\?) echo "Not a valid option."
echo "Use -${wopt} to pass options directly to wget,"
echo "or -${help} for help";; # Catch anything else.
esac
done
shift $((OPTIND - 1)) # Do funky magic stuff with $#.
if [ -z "$1" ] && [ -z "$lister" ]; then
# We should be left with at least one URL
#+ on the command-line, unless a list is
#+ being used -- catch empty CL's.
echo "No URL's given! You must enter them on the same line as wgetter2."
echo "E.g., wgetter2 http://somesite http://anothersite."
echo "Use $help option for more information."
exit $E_NO_URLS # Bail out, with appropriate error code.
fi
URLS=" $@"
# Use this so that URL list can be changed if we stay in the option loop.
while [ 1 ]; do
# This is where we ask for the most used options.
# (Mostly unchanged from version 1 of wgetter)
if [ -z $curDepth ]; then
Current=""
else Current=" Current value is $curDepth"
fi
echo "How deep should I go? \
(integer: Default is $depthDefault.$Current)"
read Depth # Recursion -- how far should we go?
inputB="" # Reset this to blank on each pass of the loop.
echo "Enter the name of the referring page (default is none)."
read inputB # Need this for some sites.
echo "Do you want to have the output logged to the terminal"
echo "(y/n, default is yes)?"
read noHide # Otherwise wget will just log it to a file.
case $noHide in # Now you see me, now you don't.
y|Y ) hide="";;
n|N ) hide=" -b";;
* ) hide="";;
esac
if [ -z ${Depth} ]; then
# User accepted either default or current depth,
#+ in which case Depth is now empty.
if [ -z ${curDepth} ]; then
# See if a depth was set on a previous iteration.
Depth="$depthDefault"
# Set the default recursion depth if nothing
#+ else to use.
else Depth="$curDepth" # Otherwise, set the one we used before.
fi
fi
Recurse=" -l $Depth" # Set how deep we want to go.
curDepth=$Depth # Remember setting for next time.
if [ ! -z $inputB ]; then
RefA=" --referer=$inputB" # Option to use referring page.
fi
WGETTER="${CommandA}${pattern}${hide}${RefA}${Recurse}\
${CookiesON}${lister}${Woptions}${URLS}"
# Just string the whole lot together . . .
# NB: no embedded spaces.
# They are in the individual elements so that if any are empty,
#+ we don't get an extra space.
if [ -z "${CookiesON}" ] && [ "$cFlag" = "1" ] ; then
echo "Warning -- can't find cookie file"
# This should be changed,
#+ in case the user has opted to not use cookies.
fi
if [ "$Flag" = "S" ]; then
echo "$WGETTER" &gt;&gt; $savePath/wget-${today}
# Create a unique filename for today, or append to it if it exists.
echo "$inputB" &gt;&gt; $savePath/site-list-${today}
# Make a list, so it's easy to refer back to,
#+ since the whole command is a bit confusing to look at.
echo "Command saved to the file $savePath/wget-${today}"
# Tell the user.
echo "Referring page URL saved to the file$ \
savePath/site-list-${today}"
# Tell the user.
Saver=" with save option"
# Stick this somewhere, so it appears in the loop if set.
else
echo "*****************"
echo "*****Getting*****"
echo "*****************"
echo ""
echo "$WGETTER"
echo ""
echo "*****************"
eval "$WGETTER"
fi
echo ""
echo "Starting over$Saver."
echo "If you want to stop, press q."
echo "Otherwise, enter some URL's:"
# Let them go again. Tell about save option being set.
read
case $REPLY in
# Need to change this to a 'trap' clause.
q|Q ) exit $E_USER_EXIT;; # Exercise for the reader?
* ) URLS=" $REPLY";;
esac
echo ""
done
exit 0
#!/bin/bash
# bashpodder.sh:
# By Linc 10/1/2004
# Find the latest script at
#+ http://linc.homeunix.org:8080/scripts/bashpodder
# Last revision 12/14/2004 - Many Contributors!
# If you use this and have made improvements or have comments
#+ drop me an email at linc dot fessenden at gmail dot com
# I'd appreciate it!
# ==&gt; ABS Guide extra comments.
# ==&gt; Author of this script has kindly granted permission
# ==&gt;+ for inclusion in ABS Guide.
# ==&gt; ################################################################
#
# ==&gt; What is "podcasting"?
# ==&gt; It's broadcasting "radio shows" over the Internet.
# ==&gt; These shows can be played on iPods and other music file players.
# ==&gt; This script makes it possible.
# ==&gt; See documentation at the script author's site, above.
# ==&gt; ################################################################
# Make script crontab friendly:
cd $(dirname $0)
# ==&gt; Change to directory where this script lives.
# datadir is the directory you want podcasts saved to:
datadir=$(date +%Y-%m-%d)
# ==&gt; Will create a date-labeled directory, named: YYYY-MM-DD
# Check for and create datadir if necessary:
if test ! -d $datadir
then
mkdir $datadir
fi
# Delete any temp file:
rm -f temp.log
# Read the bp.conf file and wget any url not already
#+ in the podcast.log file:
while read podcast
do # ==&gt; Main action follows.
file=$(wget -q $podcast -O - | tr '\r' '\n' | tr \' \" | \
sed -n 's/.*url="\([^"]*\)".*/\1/p')
for url in $file
do
echo $url &gt;&gt; temp.log
if ! grep "$url" podcast.log &gt; /dev/null
then
wget -q -P $datadir "$url"
fi
done
done < bp.conf
# Move dynamically created log file to permanent log file:
cat podcast.log &gt;&gt; temp.log
sort temp.log | uniq &gt; podcast.log
rm temp.log
# Create an m3u playlist:
ls $datadir | grep -v m3u &gt; $datadir/podcast.m3u
exit 0
#################################################
For a different scripting approach to Podcasting,
see Phil Salkie's article,
"Internet Radio to Podcast with Shell Tools"
in the September, 2005 issue of LINUX JOURNAL,
http://www.linuxjournal.com/article/8171
#################################################
#!/bin/bash
# nightly-backup.sh
# http://www.richardneill.org/source.php#nightly-backup-rsync
# Copyright (c) 2005 Richard Neill <backup@richardneill.org&gt;.
# This is Free Software licensed under the GNU GPL.
# ==&gt; Included in ABS Guide with script author's kind permission.
# ==&gt; (Thanks!)
# This does a backup from the host computer to a locally connected
#+ firewire HDD using rsync and ssh.
# (Script should work with USB-connected device (see lines 40-43).
# It then rotates the backups.
# Run it via cron every night at 5am.
# This only backs up the home directory.
# If ownerships (other than the user's) should be preserved,
#+ then run the rsync process as root (and re-instate the -o).
# We save every day for 7 days, then every week for 4 weeks,
#+ then every month for 3 months.
# See: http://www.mikerubel.org/computers/rsync_snapshots/
#+ for more explanation of the theory.
# Save as: $HOME/bin/nightly-backup_firewire-hdd.sh
# Known bugs:
# ----------
# i) Ideally, we want to exclude ~/.tmp and the browser caches.
# ii) If the user is sitting at the computer at 5am,
#+ and files are modified while the rsync is occurring,
#+ then the BACKUP_JUSTINCASE branch gets triggered.
# To some extent, this is a
#+ feature, but it also causes a "disk-space leak".
##### BEGIN CONFIGURATION SECTION ############################################
LOCAL_USER=rjn # User whose home directory should be backed up.
MOUNT_POINT=/backup # Mountpoint of backup drive.
# NO trailing slash!
# This must be unique (eg using a udev symlink)
# MOUNT_POINT=/media/disk # For USB-connected device.
SOURCE_DIR=/home/$LOCAL_USER # NO trailing slash - it DOES matter to rsync.
BACKUP_DEST_DIR=$MOUNT_POINT/backup/`hostname -s`.${LOCAL_USER}.nightly_backup
DRY_RUN=false #If true, invoke rsync with -n, to do a dry run.
# Comment out or set to false for normal use.
VERBOSE=false # If true, make rsync verbose.
# Comment out or set to false otherwise.
COMPRESS=false # If true, compress.
# Good for internet, bad on LAN.
# Comment out or set to false otherwise.
### Exit Codes ###
E_VARS_NOT_SET=64
E_COMMANDLINE=65
E_MOUNT_FAIL=70
E_NOSOURCEDIR=71
E_UNMOUNTED=72
E_BACKUP=73
##### END CONFIGURATION SECTION ##############################################
# Check that all the important variables have been set:
if [ -z "$LOCAL_USER" ] ||
[ -z "$SOURCE_DIR" ] ||
[ -z "$MOUNT_POINT" ] ||
[ -z "$BACKUP_DEST_DIR" ]
then
echo 'One of the variables is not set! Edit the file: $0. BACKUP FAILED.'
exit $E_VARS_NOT_SET
fi
if [ "$#" != 0 ] # If command-line param(s) . . .
then # Here document(ation).
cat <<-ENDOFTEXT
Automatic Nightly backup run from cron.
Read the source for more details: $0
The backup directory is $BACKUP_DEST_DIR .
It will be created if necessary; initialisation is no longer required.
WARNING: Contents of $BACKUP_DEST_DIR are rotated.
Directories named 'backup.\$i' will eventually be DELETED.
We keep backups from every day for 7 days (1-8),
then every week for 4 weeks (9-12),
then every month for 3 months (13-15).
You may wish to add this to your crontab using 'crontab -e'
# Back up files: $SOURCE_DIR to $BACKUP_DEST_DIR
#+ every night at 3:15 am
15 03 * * * /home/$LOCAL_USER/bin/nightly-backup_firewire-hdd.sh
Don't forget to verify the backups are working,
especially if you don't read cron's mail!"
ENDOFTEXT
exit $E_COMMANDLINE
fi
# Parse the options.
# ==================
if [ "$DRY_RUN" == "true" ]; then
DRY_RUN="-n"
echo "WARNING:"
echo "THIS IS A 'DRY RUN'!"
echo "No data will actually be transferred!"
else
DRY_RUN=""
fi
if [ "$VERBOSE" == "true" ]; then
VERBOSE="-v"
else
VERBOSE=""
fi
if [ "$COMPRESS" == "true" ]; then
COMPRESS="-z"
else
COMPRESS=""
fi
# Every week (actually of 8 days) and every month,
#+ extra backups are preserved.
DAY_OF_MONTH=`date +%d` # Day of month (01..31).
if [ $DAY_OF_MONTH = 01 ]; then # First of month.
MONTHSTART=true
elif [ $DAY_OF_MONTH = 08 \
-o $DAY_OF_MONTH = 16 \
-o $DAY_OF_MONTH = 24 ]; then
# Day 8,16,24 (use 8, not 7 to better handle 31-day months)
WEEKSTART=true
fi
# Check that the HDD is mounted.
# At least, check that *something* is mounted here!
# We can use something unique to the device, rather than just guessing
#+ the scsi-id by having an appropriate udev rule in
#+ /etc/udev/rules.d/10-rules.local
#+ and by putting a relevant entry in /etc/fstab.
# Eg: this udev rule:
# BUS="scsi", KERNEL="sd*", SYSFS{vendor}="WDC WD16",
# SYSFS{model}="00JB-00GVA0 ", NAME="%k", SYMLINK="lacie_1394d%n"
if mount | grep $MOUNT_POINT &gt;/dev/null; then
echo "Mount point $MOUNT_POINT is indeed mounted. OK"
else
echo -n "Attempting to mount $MOUNT_POINT..."
# If it isn't mounted, try to mount it.
sudo mount $MOUNT_POINT 2&gt;/dev/null
if mount | grep $MOUNT_POINT &gt;/dev/null; then
UNMOUNT_LATER=TRUE
echo "OK"
# Note: Ensure that this is also unmounted
#+ if we exit prematurely with failure.
else
echo "FAILED"
echo -e "Nothing is mounted at $MOUNT_POINT. BACKUP FAILED!"
exit $E_MOUNT_FAIL
fi
fi
# Check that source dir exists and is readable.
if [ ! -r $SOURCE_DIR ] ; then
echo "$SOURCE_DIR does not exist, or cannot be read. BACKUP FAILED."
exit $E_NOSOURCEDIR
fi
# Check that the backup directory structure is as it should be.
# If not, create it.
# Create the subdirectories.
# Note that backup.0 will be created as needed by rsync.
for ((i=1;i<=15;i++)); do
if [ ! -d $BACKUP_DEST_DIR/backup.$i ]; then
if /bin/mkdir -p $BACKUP_DEST_DIR/backup.$i ; then
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ No [ ] test brackets. Why?
echo "Warning: directory $BACKUP_DEST_DIR/backup.$i is missing,"
echo "or was not initialised. (Re-)creating it."
else
echo "ERROR: directory $BACKUP_DEST_DIR/backup.$i"
echo "is missing and could not be created."
if [ "$UNMOUNT_LATER" == "TRUE" ]; then
# Before we exit, unmount the mount point if necessary.
cd
sudo umount $MOUNT_POINT &&
echo "Unmounted $MOUNT_POINT again. Giving up."
fi
exit $E_UNMOUNTED
fi
fi
done
# Set the permission to 700 for security
#+ on an otherwise permissive multi-user system.
if ! /bin/chmod 700 $BACKUP_DEST_DIR ; then
echo "ERROR: Could not set permissions on $BACKUP_DEST_DIR to 700."
if [ "$UNMOUNT_LATER" == "TRUE" ]; then
# Before we exit, unmount the mount point if necessary.
cd ; sudo umount $MOUNT_POINT \
&& echo "Unmounted $MOUNT_POINT again. Giving up."
fi
exit $E_UNMOUNTED
fi
# Create the symlink: current -&gt; backup.1 if required.
# A failure here is not critical.
cd $BACKUP_DEST_DIR
if [ ! -h current ] ; then
if ! /bin/ln -s backup.1 current ; then
echo "WARNING: could not create symlink current -&gt; backup.1"
fi
fi
# Now, do the rsync.
echo "Now doing backup with rsync..."
echo "Source dir: $SOURCE_DIR"
echo -e "Backup destination dir: $BACKUP_DEST_DIR\n"
/usr/bin/rsync $DRY_RUN $VERBOSE -a -S --delete --modify-window=60 \
--link-dest=../backup.1 $SOURCE_DIR $BACKUP_DEST_DIR/backup.0/
# Only warn, rather than exit if the rsync failed,
#+ since it may only be a minor problem.
# E.g., if one file is not readable, rsync will fail.
# This shouldn't prevent the rotation.
# Not using, e.g., `date +%a` since these directories
#+ are just full of links and don't consume *that much* space.
if [ $? != 0 ]; then
BACKUP_JUSTINCASE=backup.`date +%F_%T`.justincase
echo "WARNING: the rsync process did not entirely succeed."
echo "Something might be wrong."
echo "Saving an extra copy at: $BACKUP_JUSTINCASE"
echo "WARNING: if this occurs regularly, a LOT of space will be consumed,"
echo "even though these are just hard-links!"
fi
# Save a readme in the backup parent directory.
# Save another one in the recent subdirectory.
echo "Backup of $SOURCE_DIR on `hostname` was last run on \
`date`" &gt; $BACKUP_DEST_DIR/README.txt
echo "This backup of $SOURCE_DIR on `hostname` was created on \
`date`" &gt; $BACKUP_DEST_DIR/backup.0/README.txt
# If we are not in a dry run, rotate the backups.
[ -z "$DRY_RUN" ] &&
# Check how full the backup disk is.
# Warn if 90%. if 98% or more, we'll probably fail, so give up.
# (Note: df can output to more than one line.)
# We test this here, rather than before
#+ so that rsync may possibly have a chance.
DISK_FULL_PERCENT=`/bin/df $BACKUP_DEST_DIR |
tr "\n" ' ' | awk '{print $12}' | grep -oE [0-9]+ `
echo "Disk space check on backup partition \
$MOUNT_POINT $DISK_FULL_PERCENT% full."
if [ $DISK_FULL_PERCENT -gt 90 ]; then
echo "Warning: Disk is greater than 90% full."
fi
if [ $DISK_FULL_PERCENT -gt 98 ]; then
echo "Error: Disk is full! Giving up."
if [ "$UNMOUNT_LATER" == "TRUE" ]; then
# Before we exit, unmount the mount point if necessary.
cd; sudo umount $MOUNT_POINT &&
echo "Unmounted $MOUNT_POINT again. Giving up."
fi
exit $E_UNMOUNTED
fi
# Create an extra backup.
# If this copy fails, give up.
if [ -n "$BACKUP_JUSTINCASE" ]; then
if ! /bin/cp -al $BACKUP_DEST_DIR/backup.0 \
$BACKUP_DEST_DIR/$BACKUP_JUSTINCASE
then
echo "ERROR: Failed to create extra copy \
$BACKUP_DEST_DIR/$BACKUP_JUSTINCASE"
if [ "$UNMOUNT_LATER" == "TRUE" ]; then
# Before we exit, unmount the mount point if necessary.
cd ;sudo umount $MOUNT_POINT &&
echo "Unmounted $MOUNT_POINT again. Giving up."
fi
exit $E_UNMOUNTED
fi
fi
# At start of month, rotate the oldest 8.
if [ "$MONTHSTART" == "true" ]; then
echo -e "\nStart of month. \
Removing oldest backup: $BACKUP_DEST_DIR/backup.15" &&
/bin/rm -rf $BACKUP_DEST_DIR/backup.15 &&
echo "Rotating monthly,weekly backups: \
$BACKUP_DEST_DIR/backup.[8-14] -&gt; $BACKUP_DEST_DIR/backup.[9-15]" &&
/bin/mv $BACKUP_DEST_DIR/backup.14 $BACKUP_DEST_DIR/backup.15 &&
/bin/mv $BACKUP_DEST_DIR/backup.13 $BACKUP_DEST_DIR/backup.14 &&
/bin/mv $BACKUP_DEST_DIR/backup.12 $BACKUP_DEST_DIR/backup.13 &&
/bin/mv $BACKUP_DEST_DIR/backup.11 $BACKUP_DEST_DIR/backup.12 &&
/bin/mv $BACKUP_DEST_DIR/backup.10 $BACKUP_DEST_DIR/backup.11 &&
/bin/mv $BACKUP_DEST_DIR/backup.9 $BACKUP_DEST_DIR/backup.10 &&
/bin/mv $BACKUP_DEST_DIR/backup.8 $BACKUP_DEST_DIR/backup.9
# At start of week, rotate the second-oldest 4.
elif [ "$WEEKSTART" == "true" ]; then
echo -e "\nStart of week. \
Removing oldest weekly backup: $BACKUP_DEST_DIR/backup.12" &&
/bin/rm -rf $BACKUP_DEST_DIR/backup.12 &&
echo "Rotating weekly backups: \
$BACKUP_DEST_DIR/backup.[8-11] -&gt; $BACKUP_DEST_DIR/backup.[9-12]" &&
/bin/mv $BACKUP_DEST_DIR/backup.11 $BACKUP_DEST_DIR/backup.12 &&
/bin/mv $BACKUP_DEST_DIR/backup.10 $BACKUP_DEST_DIR/backup.11 &&
/bin/mv $BACKUP_DEST_DIR/backup.9 $BACKUP_DEST_DIR/backup.10 &&
/bin/mv $BACKUP_DEST_DIR/backup.8 $BACKUP_DEST_DIR/backup.9
else
echo -e "\nRemoving oldest daily backup: $BACKUP_DEST_DIR/backup.8" &&
/bin/rm -rf $BACKUP_DEST_DIR/backup.8
fi &&
# Every day, rotate the newest 8.
echo "Rotating daily backups: \
$BACKUP_DEST_DIR/backup.[1-7] -&gt; $BACKUP_DEST_DIR/backup.[2-8]" &&
/bin/mv $BACKUP_DEST_DIR/backup.7 $BACKUP_DEST_DIR/backup.8 &&
/bin/mv $BACKUP_DEST_DIR/backup.6 $BACKUP_DEST_DIR/backup.7 &&
/bin/mv $BACKUP_DEST_DIR/backup.5 $BACKUP_DEST_DIR/backup.6 &&
/bin/mv $BACKUP_DEST_DIR/backup.4 $BACKUP_DEST_DIR/backup.5 &&
/bin/mv $BACKUP_DEST_DIR/backup.3 $BACKUP_DEST_DIR/backup.4 &&
/bin/mv $BACKUP_DEST_DIR/backup.2 $BACKUP_DEST_DIR/backup.3 &&
/bin/mv $BACKUP_DEST_DIR/backup.1 $BACKUP_DEST_DIR/backup.2 &&
/bin/mv $BACKUP_DEST_DIR/backup.0 $BACKUP_DEST_DIR/backup.1 &&
SUCCESS=true
if [ "$UNMOUNT_LATER" == "TRUE" ]; then
# Unmount the mount point if it wasn't mounted to begin with.
cd ; sudo umount $MOUNT_POINT && echo "Unmounted $MOUNT_POINT again."
fi
if [ "$SUCCESS" == "true" ]; then
echo 'SUCCESS!'
exit 0
fi
# Should have already exited if backup worked.
echo 'BACKUP FAILED! Is this just a dry run? Is the disk full?) '
exit $E_BACKUP
###########################################################################
#
# cdll
# by Phil Braham
#
# ############################################
# Latest version of this script available from
# http://freshmeat.net/projects/cd/
# ############################################
#
# .cd_new
#
# An enhancement of the Unix cd command
#
# There are unlimited stack entries and special entries. The stack
# entries keep the last cd_maxhistory
# directories that have been used. The special entries can be
# assigned to commonly used directories.
#
# The special entries may be pre-assigned by setting the environment
# variables CDSn or by using the -u or -U command.
#
# The following is a suggestion for the .profile file:
#
# . cdll # Set up the cd command
# alias cd='cd_new' # Replace the cd command
# cd -U # Upload pre-assigned entries for
# #+ the stack and special entries
# cd -D # Set non-default mode
# alias @="cd_new @" # Allow @ to be used to get history
#
# For help type:
#
# cd -h or
# cd -H
#
#
###########################################################################
#
# Version 1.2.1
#
# Written by Phil Braham - Realtime Software Pty Ltd
# (realtime@mpx.com.au)
# Please send any suggestions or enhancements to the author (also at
# phil@braham.net)
#
############################################################################
cd_hm ()
{
${PRINTF} "%s" "cd [dir] [0-9] [@[s|h] [-g [<dir&gt;]] [-d] \
[-D] [-r<n&gt;] [dir|0-9] [-R<n&gt;] [<dir&gt;|0-9]
[-s<n&gt;] [-S<n&gt;] [-u] [-U] [-f] [-F] [-h] [-H] [-v]
<dir&gt; Go to directory
0-n Go to previous directory (0 is previous, 1 is last but 1 etc)
n is up to max history (default is 50)
@ List history and special entries
@h List history entries
@s List special entries
-g [<dir&gt;] Go to literal name (bypass special names)
This is to allow access to dirs called '0','1','-h' etc
-d Change default action - verbose. (See note)
-D Change default action - silent. (See note)
-s<n&gt; Go to the special entry <n&gt;*
-S<n&gt; Go to the special entry <n&gt;
and replace it with the current dir*
-r<n&gt; [<dir&gt;] Go to directory <dir&gt;
and then put it on special entry <n&gt;*
-R<n&gt; [<dir&gt;] Go to directory <dir&gt;
and put current dir on special entry <n&gt;*
-a<n&gt; Alternative suggested directory. See note below.
-f [<file&gt;] File entries to <file&gt;.
-u [<file&gt;] Update entries from <file&gt;.
If no filename supplied then default file
(${CDPath}${2:-"$CDFile"}) is used
-F and -U are silent versions
-v Print version number
-h Help
-H Detailed help
*The special entries (0 - 9) are held until log off, replaced by another
entry or updated with the -u command
Alternative suggested directories:
If a directory is not found then CD will suggest any
possibilities. These are directories starting with the same letters
and if any are found they are listed prefixed with -a<n&gt;
where <n&gt; is a number.
It's possible to go to the directory by entering cd -a<n&gt;
on the command line.
The directory for -r<n&gt; or -R<n&gt; may be a number.
For example:
$ cd -r3 4 Go to history entry 4 and put it on special entry 3
$ cd -R3 4 Put current dir on the special entry 3
and go to history entry 4
$ cd -s3 Go to special entry 3
Note that commands R,r,S and s may be used without a number
and refer to 0:
$ cd -s Go to special entry 0
$ cd -S Go to special entry 0 and make special
entry 0 current dir
$ cd -r 1 Go to history entry 1 and put it on special entry 0
$ cd -r Go to history entry 0 and put it on special entry 0
"
if ${TEST} "$CD_MODE" = "PREV"
then
${PRINTF} "$cd_mnset"
else
${PRINTF} "$cd_mset"
fi
}
cd_Hm ()
{
cd_hm
${PRINTF} "%s" "
The previous directories (0-$cd_maxhistory) are stored in the
environment variables CD[0] - CD[$cd_maxhistory]
Similarly the special directories S0 - $cd_maxspecial are in
the environment variable CDS[0] - CDS[$cd_maxspecial]
and may be accessed from the command line
The default pathname for the -f and -u commands is $CDPath
The default filename for the -f and -u commands is $CDFile
Set the following environment variables:
CDL_PROMPTLEN - Set to the length of prompt you require.
Prompt string is set to the right characters of the
current directory.
If not set then prompt is left unchanged
CDL_PROMPT_PRE - Set to the string to prefix the prompt.
Default is:
non-root: \"\\[\\e[01;34m\\]\" (sets colour to blue).
root: \"\\[\\e[01;31m\\]\" (sets colour to red).
CDL_PROMPT_POST - Set to the string to suffix the prompt.
Default is:
non-root: \"\\[\\e[00m\\]$\"
(resets colour and displays $).
root: \"\\[\\e[00m\\]#\"
(resets colour and displays #).
CDPath - Set the default path for the -f & -u options.
Default is home directory
CDFile - Set the default filename for the -f & -u options.
Default is cdfile
"
cd_version
}
cd_version ()
{
printf "Version: ${VERSION_MAJOR}.${VERSION_MINOR} Date: ${VERSION_DATE}\n"
}
#
# Truncate right.
#
# params:
# p1 - string
# p2 - length to truncate to
#
# returns string in tcd
#
cd_right_trunc ()
{
local tlen=${2}
local plen=${#1}
local str="${1}"
local diff
local filler="<--"
if ${TEST} ${plen} -le ${tlen}
then
tcd="${str}"
else
let diff=${plen}-${tlen}
elen=3
if ${TEST} ${diff} -le 2
then
let elen=${diff}
fi
tlen=-${tlen}
let tlen=${tlen}+${elen}
tcd=${filler:0:elen}${str:tlen}
fi
}
#
# Three versions of do history:
# cd_dohistory - packs history and specials side by side
# cd_dohistoryH - Shows only hstory
# cd_dohistoryS - Shows only specials
#
cd_dohistory ()
{
cd_getrc
${PRINTF} "History:\n"
local -i count=${cd_histcount}
while ${TEST} ${count} -ge 0
do
cd_right_trunc "${CD[count]}" ${cd_lchar}
${PRINTF} "%2d %-${cd_lchar}.${cd_lchar}s " ${count} "${tcd}"
cd_right_trunc "${CDS[count]}" ${cd_rchar}
${PRINTF} "S%d %-${cd_rchar}.${cd_rchar}s\n" ${count} "${tcd}"
count=${count}-1
done
}
cd_dohistoryH ()
{
cd_getrc
${PRINTF} "History:\n"
local -i count=${cd_maxhistory}
while ${TEST} ${count} -ge 0
do
${PRINTF} "${count} %-${cd_flchar}.${cd_flchar}s\n" ${CD[$count]}
count=${count}-1
done
}
cd_dohistoryS ()
{
cd_getrc
${PRINTF} "Specials:\n"
local -i count=${cd_maxspecial}
while ${TEST} ${count} -ge 0
do
${PRINTF} "S${count} %-${cd_flchar}.${cd_flchar}s\n" ${CDS[$count]}
count=${count}-1
done
}
cd_getrc ()
{
cd_flchar=$(stty -a | awk -F \;
'/rows/ { print $2 $3 }' | awk -F \ '{ print $4 }')
if ${TEST} ${cd_flchar} -ne 0
then
cd_lchar=${cd_flchar}/2-5
cd_rchar=${cd_flchar}/2-5
cd_flchar=${cd_flchar}-5
else
cd_flchar=${FLCHAR:=75}
# cd_flchar is used for for the @s & @h history
cd_lchar=${LCHAR:=35}
cd_rchar=${RCHAR:=35}
fi
}
cd_doselection ()
{
local -i nm=0
cd_doflag="TRUE"
if ${TEST} "${CD_MODE}" = "PREV"
then
if ${TEST} -z "$cd_npwd"
then
cd_npwd=0
fi
fi
tm=$(echo "${cd_npwd}" | cut -b 1)
if ${TEST} "${tm}" = "-"
then
pm=$(echo "${cd_npwd}" | cut -b 2)
nm=$(echo "${cd_npwd}" | cut -d $pm -f2)
case "${pm}" in
a) cd_npwd=${cd_sugg[$nm]} ;;
s) cd_npwd="${CDS[$nm]}" ;;
S) cd_npwd="${CDS[$nm]}" ; CDS[$nm]=`pwd` ;;
r) cd_npwd="$2" ; cd_specDir=$nm ; cd_doselection "$1" "$2";;
R) cd_npwd="$2" ; CDS[$nm]=`pwd` ; cd_doselection "$1" "$2";;
esac
fi
if ${TEST} "${cd_npwd}" != "." -a "${cd_npwd}" \
!= ".." -a "${cd_npwd}" -le ${cd_maxhistory} &gt;&gt;/dev/null 2&gt;&1
then
cd_npwd=${CD[$cd_npwd]}
else
case "$cd_npwd" in
@) cd_dohistory ; cd_doflag="FALSE" ;;
@h) cd_dohistoryH ; cd_doflag="FALSE" ;;
@s) cd_dohistoryS ; cd_doflag="FALSE" ;;
-h) cd_hm ; cd_doflag="FALSE" ;;
-H) cd_Hm ; cd_doflag="FALSE" ;;
-f) cd_fsave "SHOW" $2 ; cd_doflag="FALSE" ;;
-u) cd_upload "SHOW" $2 ; cd_doflag="FALSE" ;;
-F) cd_fsave "NOSHOW" $2 ; cd_doflag="FALSE" ;;
-U) cd_upload "NOSHOW" $2 ; cd_doflag="FALSE" ;;
-g) cd_npwd="$2" ;;
-d) cd_chdefm 1; cd_doflag="FALSE" ;;
-D) cd_chdefm 0; cd_doflag="FALSE" ;;
-r) cd_npwd="$2" ; cd_specDir=0 ; cd_doselection "$1" "$2";;
-R) cd_npwd="$2" ; CDS[0]=`pwd` ; cd_doselection "$1" "$2";;
-s) cd_npwd="${CDS[0]}" ;;
-S) cd_npwd="${CDS[0]}" ; CDS[0]=`pwd` ;;
-v) cd_version ; cd_doflag="FALSE";;
esac
fi
}
cd_chdefm ()
{
if ${TEST} "${CD_MODE}" = "PREV"
then
CD_MODE=""
if ${TEST} $1 -eq 1
then
${PRINTF} "${cd_mset}"
fi
else
CD_MODE="PREV"
if ${TEST} $1 -eq 1
then
${PRINTF} "${cd_mnset}"
fi
fi
}
cd_fsave ()
{
local sfile=${CDPath}${2:-"$CDFile"}
if ${TEST} "$1" = "SHOW"
then
${PRINTF} "Saved to %s\n" $sfile
fi
${RM} -f ${sfile}
local -i count=0
while ${TEST} ${count} -le ${cd_maxhistory}
do
echo "CD[$count]=\"${CD[$count]}\"" &gt;&gt; ${sfile}
count=${count}+1
done
count=0
while ${TEST} ${count} -le ${cd_maxspecial}
do
echo "CDS[$count]=\"${CDS[$count]}\"" &gt;&gt; ${sfile}
count=${count}+1
done
}
cd_upload ()
{
local sfile=${CDPath}${2:-"$CDFile"}
if ${TEST} "${1}" = "SHOW"
then
${PRINTF} "Loading from %s\n" ${sfile}
fi
. ${sfile}
}
cd_new ()
{
local -i count
local -i choose=0
cd_npwd="${1}"
cd_specDir=-1
cd_doselection "${1}" "${2}"
if ${TEST} ${cd_doflag} = "TRUE"
then
if ${TEST} "${CD[0]}" != "`pwd`"
then
count=$cd_maxhistory
while ${TEST} $count -gt 0
do
CD[$count]=${CD[$count-1]}
count=${count}-1
done
CD[0]=`pwd`
fi
command cd "${cd_npwd}" 2&gt;/dev/null
if ${TEST} $? -eq 1
then
${PRINTF} "Unknown dir: %s\n" "${cd_npwd}"
local -i ftflag=0
for i in "${cd_npwd}"*
do
if ${TEST} -d "${i}"
then
if ${TEST} ${ftflag} -eq 0
then
${PRINTF} "Suggest:\n"
ftflag=1
fi
${PRINTF} "\t-a${choose} %s\n" "$i"
cd_sugg[$choose]="${i}"
choose=${choose}+1
fi
done
fi
fi
if ${TEST} ${cd_specDir} -ne -1
then
CDS[${cd_specDir}]=`pwd`
fi
if ${TEST} ! -z "${CDL_PROMPTLEN}"
then
cd_right_trunc "${PWD}" ${CDL_PROMPTLEN}
cd_rp=${CDL_PROMPT_PRE}${tcd}${CDL_PROMPT_POST}
export PS1="$(echo -ne ${cd_rp})"
fi
}
#########################################################################
# #
# Initialisation here #
# #
#########################################################################
#
VERSION_MAJOR="1"
VERSION_MINOR="2.1"
VERSION_DATE="24-MAY-2003"
#
alias cd=cd_new
#
# Set up commands
RM=/bin/rm
TEST=test
PRINTF=printf # Use builtin printf
#########################################################################
# #
# Change this to modify the default pre- and post prompt strings. #
# These only come into effect if CDL_PROMPTLEN is set. #
# #
#########################################################################
if ${TEST} ${EUID} -eq 0
then
# CDL_PROMPT_PRE=${CDL_PROMPT_PRE:="$HOSTNAME@"}
CDL_PROMPT_PRE=${CDL_PROMPT_PRE:="\\[\\e[01;31m\\]"} # Root is in red
CDL_PROMPT_POST=${CDL_PROMPT_POST:="\\[\\e[00m\\]#"}
else
CDL_PROMPT_PRE=${CDL_PROMPT_PRE:="\\[\\e[01;34m\\]"} # Users in blue
CDL_PROMPT_POST=${CDL_PROMPT_POST:="\\[\\e[00m\\]$"}
fi
#########################################################################
#
# cd_maxhistory defines the max number of history entries allowed.
typeset -i cd_maxhistory=50
#########################################################################
#
# cd_maxspecial defines the number of special entries.
typeset -i cd_maxspecial=9
#
#
#########################################################################
#
# cd_histcount defines the number of entries displayed in
#+ the history command.
typeset -i cd_histcount=9
#
#########################################################################
export CDPath=${HOME}/
# Change these to use a different #
#+ default path and filename #
export CDFile=${CDFILE:=cdfile} # for the -u and -f commands #
#
#########################################################################
#
typeset -i cd_lchar cd_rchar cd_flchar
# This is the number of chars to allow for the #
cd_flchar=${FLCHAR:=75} #+ cd_flchar is used for for the @s & @h history#
typeset -ax CD CDS
#
cd_mset="\n\tDefault mode is now set - entering cd with no parameters \
has the default action\n\tUse cd -d or -D for cd to go to \
previous directory with no parameters\n"
cd_mnset="\n\tNon-default mode is now set - entering cd with no \
parameters is the same as entering cd 0\n\tUse cd -d or \
-D to change default cd action\n"
# ==================================================================== #
: <<DOCUMENTATION
Written by Phil Braham. Realtime Software Pty Ltd.
Released under GNU license. Free to use. Please pass any modifications
or comments to the author Phil Braham:
realtime@mpx.com.au
=======================================================================
cdll is a replacement for cd and incorporates similar functionality to
the bash pushd and popd commands but is independent of them.
This version of cdll has been tested on Linux using Bash. It will work
on most Linux versions but will probably not work on other shells without
modification.
Introduction
============
cdll allows easy moving about between directories. When changing to a new
directory the current one is automatically put onto a stack. By default
50 entries are kept, but this is configurable. Special directories can be
kept for easy access - by default up to 10, but this is configurable. The
most recent stack entries and the special entries can be easily viewed.
The directory stack and special entries can be saved to, and loaded from,
a file. This allows them to be set up on login, saved before logging out
or changed when moving project to project.
In addition, cdll provides a flexible command prompt facility that allows,
for example, a directory name in colour that is truncated from the left
if it gets too long.
Setting up cdll
===============
Copy cdll to either your local home directory or a central directory
such as /usr/bin (this will require root access).
Copy the file cdfile to your home directory. It will require read and
write access. This a default file that contains a directory stack and
special entries.
To replace the cd command you must add commands to your login script.
The login script is one or more of:
/etc/profile
~/.bash_profile
~/.bash_login
~/.profile
~/.bashrc
/etc/bash.bashrc.local
To setup your login, ~/.bashrc is recommended, for global (and root) setup
add the commands to /etc/bash.bashrc.local
To set up on login, add the command:
. <dir&gt;/cdll
For example if cdll is in your local home directory:
. ~/cdll
If in /usr/bin then:
. /usr/bin/cdll
If you want to use this instead of the buitin cd command then add:
alias cd='cd_new'
We would also recommend the following commands:
alias @='cd_new @'
cd -U
cd -D
If you want to use cdll's prompt facilty then add the following:
CDL_PROMPTLEN=nn
Where nn is a number described below. Initially 99 would be suitable
number.
Thus the script looks something like this:
######################################################################
# CD Setup
######################################################################
CDL_PROMPTLEN=21 # Allow a prompt length of up to 21 characters
. /usr/bin/cdll # Initialise cdll
alias cd='cd_new' # Replace the built in cd command
alias @='cd_new @' # Allow @ at the prompt to display history
cd -U # Upload directories
cd -D # Set default action to non-posix
######################################################################
The full meaning of these commands will become clear later.
There are a couple of caveats. If another program changes the directory
without calling cdll, then the directory won't be put on the stack and
also if the prompt facility is used then this will not be updated. Two
programs that can do this are pushd and popd. To update the prompt and
stack simply enter:
cd .
Note that if the previous entry on the stack is the current directory
then the stack is not updated.
Usage
=====
cd [dir] [0-9] [@[s|h] [-g <dir&gt;] [-d] [-D] [-r<n&gt;]
[dir|0-9] [-R<n&gt;] [<dir&gt;|0-9] [-s<n&gt;] [-S<n&gt;]
[-u] [-U] [-f] [-F] [-h] [-H] [-v]
<dir&gt; Go to directory
0-n Goto previous directory (0 is previous,
1 is last but 1, etc.)
n is up to max history (default is 50)
@ List history and special entries (Usually available as $ @)
@h List history entries
@s List special entries
-g [<dir&gt;] Go to literal name (bypass special names)
This is to allow access to dirs called '0','1','-h' etc
-d Change default action - verbose. (See note)
-D Change default action - silent. (See note)
-s<n&gt; Go to the special entry <n&gt;
-S<n&gt; Go to the special entry <n&gt;
and replace it with the current dir
-r<n&gt; [<dir&gt;] Go to directory <dir&gt;
and then put it on special entry <n&gt;
-R<n&gt; [<dir&gt;] Go to directory <dir&gt;
and put current dir on special entry <n&gt;
-a<n&gt; Alternative suggested directory. See note below.
-f [<file&gt;] File entries to <file&gt;.
-u [<file&gt;] Update entries from <file&gt;.
If no filename supplied then default file (~/cdfile) is used
-F and -U are silent versions
-v Print version number
-h Help
-H Detailed help
Examples
========
These examples assume non-default mode is set (that is, cd with no
parameters will go to the most recent stack directory), that aliases
have been set up for cd and @ as described above and that cd's prompt
facility is active and the prompt length is 21 characters.
/home/phil$ @
# List the entries with the @
History:
# Output of the @ command
.....
# Skipped these entries for brevity
1 /home/phil/ummdev S1 /home/phil/perl
# Most recent two history entries
0 /home/phil/perl/eg S0 /home/phil/umm/ummdev
# and two special entries are shown
/home/phil$ cd /home/phil/utils/Cdll
# Now change directories
/home/phil/utils/Cdll$ @
# Prompt reflects the directory.
History:
# New history
.....
1 /home/phil/perl/eg S1 /home/phil/perl
# History entry 0 has moved to 1
0 /home/phil S0 /home/phil/umm/ummdev
# and the most recent has entered
To go to a history entry:
/home/phil/utils/Cdll$ cd 1
# Go to history entry 1.
/home/phil/perl/eg$
# Current directory is now what was 1
To go to a special entry:
/home/phil/perl/eg$ cd -s1
# Go to special entry 1
/home/phil/umm/ummdev$
# Current directory is S1
To go to a directory called, for example, 1:
/home/phil$ cd -g 1
# -g ignores the special meaning of 1
/home/phil/1$
To put current directory on the special list as S1:
cd -r1 . # OR
cd -R1 . # These have the same effect if the directory is
#+ . (the current directory)
To go to a directory and add it as a special
The directory for -r<n&gt; or -R<n&gt; may be a number.
For example:
$ cd -r3 4 Go to history entry 4 and put it on special entry 3
$ cd -R3 4 Put current dir on the special entry 3 and go to
history entry 4
$ cd -s3 Go to special entry 3
Note that commands R,r,S and s may be used without a number and
refer to 0:
$ cd -s Go to special entry 0
$ cd -S Go to special entry 0 and make special entry 0
current dir
$ cd -r 1 Go to history entry 1 and put it on special entry 0
$ cd -r Go to history entry 0 and put it on special entry 0
Alternative suggested directories:
If a directory is not found, then CD will suggest any
possibilities. These are directories starting with the same letters
and if any are found they are listed prefixed with -a<n&gt;
where <n&gt; is a number. It's possible to go to the directory
by entering cd -a<n&gt; on the command line.
Use cd -d or -D to change default cd action. cd -H will show
current action.
The history entries (0-n) are stored in the environment variables
CD[0] - CD[n]
Similarly the special directories S0 - 9 are in the environment
variable CDS[0] - CDS[9]
and may be accessed from the command line, for example:
ls -l ${CDS[3]}
cat ${CD[8]}/file.txt
The default pathname for the -f and -u commands is ~
The default filename for the -f and -u commands is cdfile
Configuration
=============
The following environment variables can be set:
CDL_PROMPTLEN - Set to the length of prompt you require.
Prompt string is set to the right characters of the current
directory. If not set, then prompt is left unchanged. Note
that this is the number of characters that the directory is
shortened to, not the total characters in the prompt.
CDL_PROMPT_PRE - Set to the string to prefix the prompt.
Default is:
non-root: "\\[\\e[01;34m\\]" (sets colour to blue).
root: "\\[\\e[01;31m\\]" (sets colour to red).
CDL_PROMPT_POST - Set to the string to suffix the prompt.
Default is:
non-root: "\\[\\e[00m\\]$"
(resets colour and displays $).
root: "\\[\\e[00m\\]#"
(resets colour and displays #).
Note:
CDL_PROMPT_PRE & _POST only t
CDPath - Set the default path for the -f & -u options.
Default is home directory
CDFile - Set the default filename for the -f & -u options.
Default is cdfile
There are three variables defined in the file cdll which control the
number of entries stored or displayed. They are in the section labeled
'Initialisation here' towards the end of the file.
cd_maxhistory - The number of history entries stored.
Default is 50.
cd_maxspecial - The number of special entries allowed.
Default is 9.
cd_histcount - The number of history and special entries
displayed. Default is 9.
Note that cd_maxspecial should be &gt;= cd_histcount to avoid displaying
special entries that can't be set.
Version: 1.2.1 Date: 24-MAY-2003
DOCUMENTATION
#!/bin/bash
# soundcard-on.sh
# Script author: Mkarcher
# http://www.thinkwiki.org/wiki ...
# /Script_for_configuring_the_CS4239_sound_chip_in_PnP_mode
# ABS Guide author made minor changes and added comments.
# Couldn't contact script author to ask for permission to use, but ...
#+ the script was released under the FDL,
#+ so its use here should be both legal and ethical.
# Sound-via-pnp-script for Thinkpad 600E
#+ and possibly other computers with onboard CS4239/CS4610
#+ that do not work with the PCI driver
#+ and are not recognized by the PnP code of snd-cs4236.
# Also for some 770-series Thinkpads, such as the 770x.
# Run as root user, of course.
#
# These are old and very obsolete laptop computers,
#+ but this particular script is very instructive,
#+ as it shows how to set up and hack device files.
# Search for sound card pnp device:
for dev in /sys/bus/pnp/devices/*
do
grep CSC0100 $dev/id &gt; /dev/null && WSSDEV=$dev
grep CSC0110 $dev/id &gt; /dev/null && CTLDEV=$dev
done
# On 770x:
# WSSDEV = /sys/bus/pnp/devices/00:07
# CTLDEV = /sys/bus/pnp/devices/00:06
# These are symbolic links to /sys/devices/pnp0/ ...
# Activate devices:
# Thinkpad boots with devices disabled unless "fast boot" is turned off
#+ (in BIOS).
echo activate &gt; $WSSDEV/resources
echo activate &gt; $CTLDEV/resources
# Parse resource settings.
{ read # Discard "state = active" (see below).
read bla port1
read bla port2
read bla port3
read bla irq
read bla dma1
read bla dma2
# The "bla's" are labels in the first field: "io," "state," etc.
# These are discarded.
# Hack: with PnPBIOS: ports are: port1: WSS, port2:
#+ OPL, port3: sb (unneeded)
# with ACPI-PnP:ports are: port1: OPL, port2: sb, port3: WSS
# (ACPI bios seems to be wrong here, the PnP-card-code in snd-cs4236.c
#+ uses the PnPBIOS port order)
# Detect port order using the fixed OPL port as reference.
if [ ${port2%%-*} = 0x388 ]
# ^^^^ Strip out everything following hyphen in port address.
# So, if port1 is 0x530-0x537
#+ we're left with 0x530 -- the start address of the port.
then
# PnPBIOS: usual order
port=${port1%%-*}
oplport=${port2%%-*}
else
# ACPI: mixed-up order
port=${port3%%-*}
oplport=${port1%%-*}
fi
} < $WSSDEV/resources
# To see what's going on here:
# ---------------------------
# cat /sys/devices/pnp0/00:07/resources
#
# state = active
# io 0x530-0x537
# io 0x388-0x38b
# io 0x220-0x233
# irq 5
# dma 1
# dma 0
# ^^^ "bla" labels in first field (discarded).
{ read # Discard first line, as above.
read bla port1
cport=${port1%%-*}
# ^^^^
# Just want _start_ address of port.
} < $CTLDEV/resources
# Load the module:
modprobe --ignore-install snd-cs4236 port=$port cport=$cport\
fm_port=$oplport irq=$irq dma1=$dma1 dma2=$dma2 isapnp=0 index=0
# See the modprobe manpage.
exit $?
#!/bin/bash
# find-splitpara.sh
# Finds split paragraphs in a text file,
#+ and tags the line numbers.
ARGCOUNT=1 # Expect one arg.
OFF=0 # Flag states.
ON=1
E_WRONGARGS=85
file="$1" # Target filename.
lineno=1 # Line number. Start at 1.
Flag=$OFF # Blank line flag.
if [ $# -ne "$ARGCOUNT" ]
then
echo "Usage: `basename $0` FILENAME"
exit $E_WRONGARGS
fi
file_read () # Scan file for pattern, then print line.
{
while read line
do
if [[ "$line" =~ ^[a-z] && $Flag -eq $ON ]]
then # Line begins with lowercase character, following blank line.
echo -n "$lineno:: "
echo "$line"
fi
if [[ "$line" =~ ^$ ]]
then # If blank line,
Flag=$ON #+ set flag.
else
Flag=$OFF
fi
((lineno++))
done
} < $file # Redirect file into function's stdin.
file_read
exit $?
# ----------------------------------------------------------------
This is line one of an example paragraph, bla, bla, bla.
This is line two, and line three should follow on next line, but
there is a blank line separating the two parts of the paragraph.
# ----------------------------------------------------------------
Running this script on a file containing the above paragraph
yields:
4:: there is a blank line separating the two parts of the paragraph.
There will be additional output for all the other split paragraphs
in the target file.
#!/bin/bash
# insertion-sort.bash: Insertion sort implementation in Bash
# Heavy use of Bash array features:
#+ (string) slicing, merging, etc
# URL: http://www.lugmen.org.ar/~jjo/jjotip/insertion-sort.bash.d
#+ /insertion-sort.bash.sh
#
# Author: JuanJo Ciarlante <jjo@irrigacion.gov.ar&gt;
# Lightly reformatted by ABS Guide author.
# License: GPLv2
# Used in ABS Guide with author's permission (thanks!).
#
# Test with: ./insertion-sort.bash -t
# Or: bash insertion-sort.bash -t
# The following *doesn't* work:
# sh insertion-sort.bash -t
# Why not? Hint: which Bash-specific features are disabled
#+ when running a script by 'sh script.sh'?
#
: ${DEBUG:=0} # Debug, override with: DEBUG=1 ./scriptname . . .
# Parameter substitution -- set DEBUG to 0 if not previously set.
# Global array: "list"
typeset -a list
# Load whitespace-separated numbers from stdin.
if [ "$1" = "-t" ]; then
DEBUG=1
read -a list < <( od -Ad -w24 -t u2 /dev/urandom ) # Random list.
# ^ ^ process substition
else
read -a list
fi
numelem=${#list[*]}
# Shows the list, marking the element whose index is $1
#+ by surrounding it with the two chars passed as $2.
# Whole line prefixed with $3.
showlist()
{
echo "$3"${list[@]:0:$1} ${2:0:1}${list[$1]}${2:1:1} ${list[@]:$1+1};
}
# Loop _pivot_ -- from second element to end of list.
for(( i=1; i<numelem; i++ )) do
((DEBUG))&&showlist i "[]" " "
# From current _pivot_, back to first element.
for(( j=i; j; j-- )) do
# Search for the 1st elem. less than current "pivot" . . .
[[ "${list[j-1]}" -le "${list[i]}" ]] && break
done
(( i==j )) && continue ## No insertion was needed for this element.
# . . . Move list[i] (pivot) to the left of list[j]:
list=(${list[@]:0:j} ${list[i]} ${list[j]}\
# {0,j-1} {i} {j}
${list[@]:j+1:i-(j+1)} ${list[@]:i+1})
# {j+1,i-1} {i+1,last}
((DEBUG))&&showlist j "<&gt;" "*"
done
echo
echo "------"
echo $'Result:\n'${list[@]}
exit $?
#!/bin/bash
# sd.sh: Standard Deviation
# The Standard Deviation indicates how consistent a set of data is.
# It shows to what extent the individual data points deviate from the
#+ arithmetic mean, i.e., how much they "bounce around" (or cluster).
# It is essentially the average deviation-distance of the
#+ data points from the mean.
# =========================================================== #
# To calculate the Standard Deviation:
#
# 1 Find the arithmetic mean (average) of all the data points.
# 2 Subtract each data point from the arithmetic mean,
# and square that difference.
# 3 Add all of the individual difference-squares in # 2.
# 4 Divide the sum in # 3 by the number of data points.
# This is known as the "variance."
# 5 The square root of # 4 gives the Standard Deviation.
# =========================================================== #
count=0 # Number of data points; global.
SC=9 # Scale to be used by bc. Nine decimal places.
E_DATAFILE=90 # Data file error.
# ----------------- Set data file ---------------------
if [ ! -z "$1" ] # Specify filename as cmd-line arg?
then
datafile="$1" # ASCII text file,
else #+ one (numerical) data point per line!
datafile=sample.dat
fi # See example data file, below.
if [ ! -e "$datafile" ]
then
echo "\""$datafile"\" does not exist!"
exit $E_DATAFILE
fi
# -----------------------------------------------------
arith_mean ()
{
local rt=0 # Running total.
local am=0 # Arithmetic mean.
local ct=0 # Number of data points.
while read value # Read one data point at a time.
do
rt=$(echo "scale=$SC; $rt + $value" | bc)
(( ct++ ))
done
am=$(echo "scale=$SC; $rt / $ct" | bc)
echo $am; return $ct # This function "returns" TWO values!
# Caution: This little trick will not work if $ct &gt; 255!
# To handle a larger number of data points,
#+ simply comment out the "return $ct" above.
} <"$datafile" # Feed in data file.
sd ()
{
mean1=$1 # Arithmetic mean (passed to function).
n=$2 # How many data points.
sum2=0 # Sum of squared differences ("variance").
avg2=0 # Average of $sum2.
sdev=0 # Standard Deviation.
while read value # Read one line at a time.
do
diff=$(echo "scale=$SC; $mean1 - $value" | bc)
# Difference between arith. mean and data point.
dif2=$(echo "scale=$SC; $diff * $diff" | bc) # Squared.
sum2=$(echo "scale=$SC; $sum2 + $dif2" | bc) # Sum of squares.
done
avg2=$(echo "scale=$SC; $sum2 / $n" | bc) # Avg. of sum of squares.
sdev=$(echo "scale=$SC; sqrt($avg2)" | bc) # Square root =
echo $sdev # Standard Deviation.
} <"$datafile" # Rewinds data file.
# ======================================================= #
mean=$(arith_mean); count=$? # Two returns from function!
std_dev=$(sd $mean $count)
echo
echo "Number of data points in \""$datafile"\" = $count"
echo "Arithmetic mean (average) = $mean"
echo "Standard Deviation = $std_dev"
echo
# ======================================================= #
exit
# This script could stand some drastic streamlining,
#+ but not at the cost of reduced legibility, please.
# ++++++++++++++++++++++++++++++++++++++++ #
# A sample data file (sample1.dat):
# 18.35
# 19.0
# 18.88
# 18.91
# 18.64
# $ sh sd.sh sample1.dat
# Number of data points in "sample1.dat" = 5
# Arithmetic mean (average) = 18.756000000
# Standard Deviation = .235338054
# ++++++++++++++++++++++++++++++++++++++++ #
#!/bin/bash
# pad.sh
#######################################################
# PAD (xml) file creator
#+ Written by Mendel Cooper <thegrendel.abs@gmail.com&gt;.
#+ Released to the Public Domain.
#
# Generates a "PAD" descriptor file for shareware
#+ packages, according to the specifications
#+ of the ASP.
# http://www.asp-shareware.org/pad
#######################################################
# Accepts (optional) save filename as a command-line argument.
if [ -n "$1" ]
then
savefile=$1
else
savefile=save_file.xml # Default save_file name.
fi
# ===== PAD file headers =====
HDR1="<?xml version=\"1.0\" encoding=\"Windows-1252\" ?&gt;"
HDR2="<XML_DIZ_INFO&gt;"
HDR3="<MASTER_PAD_VERSION_INFO&gt;"
HDR4="\t<MASTER_PAD_VERSION&gt;1.15</MASTER_PAD_VERSION&gt;"
HDR5="\t<MASTER_PAD_INFO&gt;Portable Application Description, or PAD
for short, is a data set that is used by shareware authors to
disseminate information to anyone interested in their software products.
To find out more go to http://www.asp-shareware.org/pad</MASTER_PAD_INFO&gt;"
HDR6="</MASTER_PAD_VERSION_INFO&gt;"
# ============================
fill_in ()
{
if [ -z "$2" ]
then
echo -n "$1? " # Get user input.
else
echo -n "$1 $2? " # Additional query?
fi
read var # May paste to fill in field.
# This shows how flexible "read" can be.
if [ -z "$var" ]
then
echo -e "\t\t<$1 /&gt;" &gt;&gt;$savefile # Indent with 2 tabs.
return
else
echo -e "\t\t<$1&gt;$var</$1&gt;" &gt;&gt;$savefile
return ${#var} # Return length of input string.
fi
}
check_field_length () # Check length of program description fields.
{
# $1 = maximum field length
# $2 = actual field length
if [ "$2" -gt "$1" ]
then
echo "Warning: Maximum field length of $1 characters exceeded!"
fi
}
clear # Clear screen.
echo "PAD File Creator"
echo "--- ---- -------"
echo
# Write File Headers to file.
echo $HDR1 &gt;$savefile
echo $HDR2 &gt;&gt;$savefile
echo $HDR3 &gt;&gt;$savefile
echo -e $HDR4 &gt;&gt;$savefile
echo -e $HDR5 &gt;&gt;$savefile
echo $HDR6 &gt;&gt;$savefile
# Company_Info
echo "COMPANY INFO"
CO_HDR="Company_Info"
echo "<$CO_HDR&gt;" &gt;&gt;$savefile
fill_in Company_Name
fill_in Address_1
fill_in Address_2
fill_in City_Town
fill_in State_Province
fill_in Zip_Postal_Code
fill_in Country
# If applicable:
# fill_in ASP_Member "[Y/N]"
# fill_in ASP_Member_Number
# fill_in ESC_Member "[Y/N]"
fill_in Company_WebSite_URL
clear # Clear screen between sections.
# Contact_Info
echo "CONTACT INFO"
CONTACT_HDR="Contact_Info"
echo "<$CONTACT_HDR&gt;" &gt;&gt;$savefile
fill_in Author_First_Name
fill_in Author_Last_Name
fill_in Author_Email
fill_in Contact_First_Name
fill_in Contact_Last_Name
fill_in Contact_Email
echo -e "\t</$CONTACT_HDR&gt;" &gt;&gt;$savefile
# END Contact_Info
clear
# Support_Info
echo "SUPPORT INFO"
SUPPORT_HDR="Support_Info"
echo "<$SUPPORT_HDR&gt;" &gt;&gt;$savefile
fill_in Sales_Email
fill_in Support_Email
fill_in General_Email
fill_in Sales_Phone
fill_in Support_Phone
fill_in General_Phone
fill_in Fax_Phone
echo -e "\t</$SUPPORT_HDR&gt;" &gt;&gt;$savefile
# END Support_Info
echo "</$CO_HDR&gt;" &gt;&gt;$savefile
# END Company_Info
clear
# Program_Info
echo "PROGRAM INFO"
PROGRAM_HDR="Program_Info"
echo "<$PROGRAM_HDR&gt;" &gt;&gt;$savefile
fill_in Program_Name
fill_in Program_Version
fill_in Program_Release_Month
fill_in Program_Release_Day
fill_in Program_Release_Year
fill_in Program_Cost_Dollars
fill_in Program_Cost_Other
fill_in Program_Type "[Shareware/Freeware/GPL]"
fill_in Program_Release_Status "[Beta, Major Upgrade, etc.]"
fill_in Program_Install_Support
fill_in Program_OS_Support "[Win9x/Win2k/Linux/etc.]"
fill_in Program_Language "[English/Spanish/etc.]"
echo; echo
# File_Info
echo "FILE INFO"
FILEINFO_HDR="File_Info"
echo "<$FILEINFO_HDR&gt;" &gt;&gt;$savefile
fill_in Filename_Versioned
fill_in Filename_Previous
fill_in Filename_Generic
fill_in Filename_Long
fill_in File_Size_Bytes
fill_in File_Size_K
fill_in File_Size_MB
echo -e "\t</$FILEINFO_HDR&gt;" &gt;&gt;$savefile
# END File_Info
clear
# Expire_Info
echo "EXPIRE INFO"
EXPIRE_HDR="Expire_Info"
echo "<$EXPIRE_HDR&gt;" &gt;&gt;$savefile
fill_in Has_Expire_Info "Y/N"
fill_in Expire_Count
fill_in Expire_Based_On
fill_in Expire_Other_Info
fill_in Expire_Month
fill_in Expire_Day
fill_in Expire_Year
echo -e "\t</$EXPIRE_HDR&gt;" &gt;&gt;$savefile
# END Expire_Info
clear
# More Program_Info
echo "ADDITIONAL PROGRAM INFO"
fill_in Program_Change_Info
fill_in Program_Specific_Category
fill_in Program_Categories
fill_in Includes_JAVA_VM "[Y/N]"
fill_in Includes_VB_Runtime "[Y/N]"
fill_in Includes_DirectX "[Y/N]"
# END More Program_Info
echo "</$PROGRAM_HDR&gt;" &gt;&gt;$savefile
# END Program_Info
clear
# Program Description
echo "PROGRAM DESCRIPTIONS"
PROGDESC_HDR="Program_Descriptions"
echo "<$PROGDESC_HDR&gt;" &gt;&gt;$savefile
LANG="English"
echo "<$LANG&gt;" &gt;&gt;$savefile
fill_in Keywords "[comma + space separated]"
echo
echo "45, 80, 250, 450, 2000 word program descriptions"
echo "(may cut and paste into field)"
# It would be highly appropriate to compose the following
#+ "Char_Desc" fields with a text editor,
#+ then cut-and-paste the text into the answer fields.
echo
echo " |---------------45 characters---------------|"
fill_in Char_Desc_45
check_field_length 45 "$?"
echo
fill_in Char_Desc_80
check_field_length 80 "$?"
fill_in Char_Desc_250
check_field_length 250 "$?"
fill_in Char_Desc_450
fill_in Char_Desc_2000
echo "</$LANG&gt;" &gt;&gt;$savefile
echo "</$PROGDESC_HDR&gt;" &gt;&gt;$savefile
# END Program Description
clear
echo "Done."; echo; echo
echo "Save file is: \""$savefile"\""
exit 0
#!/bin/bash
# maned.sh
# A rudimentary man page editor
# Version: 0.1 (Alpha, probably buggy)
# Author: Mendel Cooper <thegrendel.abs@gmail.com&gt;
# Reldate: 16 June 2008
# License: GPL3
savefile= # Global, used in multiple functions.
E_NOINPUT=90 # User input missing (error). May or may not be critical.
# =========== Markup Tags ============ #
TopHeader=".TH"
NameHeader=".SH NAME"
SyntaxHeader=".SH SYNTAX"
SynopsisHeader=".SH SYNOPSIS"
InstallationHeader=".SH INSTALLATION"
DescHeader=".SH DESCRIPTION"
OptHeader=".SH OPTIONS"
FilesHeader=".SH FILES"
EnvHeader=".SH ENVIRONMENT"
AuthHeader=".SH AUTHOR"
BugsHeader=".SH BUGS"
SeeAlsoHeader=".SH SEE ALSO"
BOLD=".B"
# Add more tags, as needed.
# See groff docs for markup meanings.
# ==================================== #
start ()
{
clear # Clear screen.
echo "ManEd"
echo "-----"
echo
echo "Simple man page creator"
echo "Author: Mendel Cooper"
echo "License: GPL3"
echo; echo; echo
}
progname ()
{
echo -n "Program name? "
read name
echo -n "Manpage section? [Hit RETURN for default (\"1\") ] "
read section
if [ -z "$section" ]
then
section=1 # Most man pages are in section 1.
fi
if [ -n "$name" ]
then
savefile=""$name"."$section"" # Filename suffix = section.
echo -n "$1 " &gt;&gt;$savefile
name1=$(echo "$name" | tr a-z A-Z) # Change to uppercase,
#+ per man page convention.
echo -n "$name1" &gt;&gt;$savefile
else
echo "Error! No input." # Mandatory input.
exit $E_NOINPUT # Critical!
# Exercise: The script-abort if no filename input is a bit clumsy.
# Rewrite this section so a default filename is used
#+ if no input.
fi
echo -n " \"$section\""&gt;&gt;$savefile # Append, always append.
echo -n "Version? "
read ver
echo -n " \"Version $ver \""&gt;&gt;$savefile
echo &gt;&gt;$savefile
echo -n "Short description [0 - 5 words]? "
read sdesc
echo "$NameHeader"&gt;&gt;$savefile
echo ""$BOLD" "$name""&gt;&gt;$savefile
echo "\- "$sdesc""&gt;&gt;$savefile
}
fill_in ()
{ # This function more or less copied from "pad.sh" script.
echo -n "$2? " # Get user input.
read var # May paste (a single line only!) to fill in field.
if [ -n "$var" ]
then
echo "$1 " &gt;&gt;$savefile
echo -n "$var" &gt;&gt;$savefile
else # Don't append empty field to file.
return $E_NOINPUT # Not critical here.
fi
echo &gt;&gt;$savefile
}
end ()
{
clear
echo -n "Would you like to view the saved man page (y/n)? "
read ans
if [ "$ans" = "n" -o "$ans" = "N" ]; then exit; fi
exec less "$savefile" # Exit script and hand off control to "less" ...
#+ ... which formats for viewing man page source.
}
# ---------------------------------------- #
start
progname "$TopHeader"
fill_in "$SynopsisHeader" "Synopsis"
fill_in "$DescHeader" "Long description"
# May paste in *single line* of text.
fill_in "$OptHeader" "Options"
fill_in "$FilesHeader" "Files"
fill_in "$AuthHeader" "Author"
fill_in "$BugsHeader" "Bugs"
fill_in "$SeeAlsoHeader" "See also"
# fill_in "$OtherHeader" ... as necessary.
end # ... exit not needed.
# ---------------------------------------- #
# Note that the generated man page will usually
#+ require manual fine-tuning with a text editor.
# However, it's a distinct improvement upon
#+ writing man source from scratch
#+ or even editing a blank man page template.
# The main deficiency of the script is that it permits
#+ pasting only a single text line into the input fields.
# This may be a long, cobbled-together line, which groff
# will automatically wrap and hyphenate.
# However, if you want multiple (newline-separated) paragraphs,
#+ these must be inserted by manual text editing on the
#+ script-generated man page.
# Exercise (difficult): Fix this!
# This script is not nearly as elaborate as the
#+ full-featured "manedit" package
#+ http://freshmeat.net/projects/manedit/
#+ but it's much easier to use.
#!/bin/bash -i
# petals.sh
#########################################################################
# Petals Around the Rose #
# #
# Version 0.1 Created by Serghey Rodin #
# Version 0.2 Modded by ABS Guide Author #
# #
# License: GPL3 #
# Used in ABS Guide with permission. #
# ##################################################################### #
hits=0 # Correct guesses.
WIN=6 # Mastered the game.
ALMOST=5 # One short of mastery.
EXIT=exit # Give up early?
RANDOM=$$ # Seeds the random number generator from PID of script.
# Bones (ASCII graphics for dice)
bone1[1]="| |"
bone1[2]="| o |"
bone1[3]="| o |"
bone1[4]="| o o |"
bone1[5]="| o o |"
bone1[6]="| o o |"
bone2[1]="| o |"
bone2[2]="| |"
bone2[3]="| o |"
bone2[4]="| |"
bone2[5]="| o |"
bone2[6]="| o o |"
bone3[1]="| |"
bone3[2]="| o |"
bone3[3]="| o |"
bone3[4]="| o o |"
bone3[5]="| o o |"
bone3[6]="| o o |"
bone="+---------+"
# Functions
instructions () {
clear
echo -n "Do you need instructions? (y/n) "; read ans
if [ "$ans" = "y" -o "$ans" = "Y" ]; then
clear
echo -e '\E[34;47m' # Blue type.
# "cat document"
cat <<INSTRUCTIONSZZZ
The name of the game is Petals Around the Rose,
and that name is significant.
Five dice will roll and you must guess the "answer" for each roll.
It will be zero or an even number.
After your guess, you will be told the answer for the roll, but . . .
that's ALL the information you will get.
Six consecutive correct guesses admits you to the
Fellowship of the Rose.
INSTRUCTIONSZZZ
echo -e "\033[0m" # Turn off blue.
else clear
fi
}
fortune ()
{
RANGE=7
FLOOR=0
number=0
while [ "$number" -le $FLOOR ]
do
number=$RANDOM
let "number %= $RANGE" # 1 - 6.
done
return $number
}
throw () { # Calculate each individual die.
fortune; B1=$?
fortune; B2=$?
fortune; B3=$?
fortune; B4=$?
fortune; B5=$?
calc () { # Function embedded within a function!
case "$1" in
3 ) rose=2;;
5 ) rose=4;;
* ) rose=0;;
esac # Simplified algorithm.
# Doesn't really get to the heart of the matter.
return $rose
}
answer=0
calc "$B1"; answer=$(expr $answer + $(echo $?))
calc "$B2"; answer=$(expr $answer + $(echo $?))
calc "$B3"; answer=$(expr $answer + $(echo $?))
calc "$B4"; answer=$(expr $answer + $(echo $?))
calc "$B5"; answer=$(expr $answer + $(echo $?))
}
game ()
{ # Generate graphic display of dice throw.
throw
echo -e "\033[1m" # Bold.
echo -e "\n"
echo -e "$bone\t$bone\t$bone\t$bone\t$bone"
echo -e \
"${bone1[$B1]}\t${bone1[$B2]}\t${bone1[$B3]}\t${bone1[$B4]}\t${bone1[$B5]}"
echo -e \
"${bone2[$B1]}\t${bone2[$B2]}\t${bone2[$B3]}\t${bone2[$B4]}\t${bone2[$B5]}"
echo -e \
"${bone3[$B1]}\t${bone3[$B2]}\t${bone3[$B3]}\t${bone3[$B4]}\t${bone3[$B5]}"
echo -e "$bone\t$bone\t$bone\t$bone\t$bone"
echo -e "\n\n\t\t"
echo -e "\033[0m" # Turn off bold.
echo -n "There are how many petals around the rose? "
}
# ============================================================== #
instructions
while [ "$petal" != "$EXIT" ] # Main loop.
do
game
read petal
echo "$petal" | grep [0-9] &gt;/dev/null # Filter response for digit.
# Otherwise just roll dice again.
if [ "$?" -eq 0 ] # If-loop #1.
then
if [ "$petal" == "$answer" ]; then # If-loop #2.
echo -e "\nCorrect. There are $petal petals around the rose.\n"
(( hits++ ))
if [ "$hits" -eq "$WIN" ]; then # If-loop #3.
echo -e '\E[31;47m' # Red type.
echo -e "\033[1m" # Bold.
echo "You have unraveled the mystery of the Rose Petals!"
echo "Welcome to the Fellowship of the Rose!!!"
echo "(You are herewith sworn to secrecy.)"; echo
echo -e "\033[0m" # Turn off red & bold.
break # Exit!
else echo "You have $hits correct so far."; echo
if [ "$hits" -eq "$ALMOST" ]; then
echo "Just one more gets you to the heart of the mystery!"; echo
fi
fi # Close if-loop #3.
else
echo -e "\nWrong. There are $answer petals around the rose.\n"
hits=0 # Reset number of correct guesses.
fi # Close if-loop #2.
echo -n "Hit ENTER for the next roll, or type \"exit\" to end. "
read
if [ "$REPLY" = "$EXIT" ]; then exit
fi
fi # Close if-loop #1.
clear
done # End of main (while) loop.
###
exit $?
# Resources:
# ---------
# 1) http://en.wikipedia.org/wiki/Petals_Around_the_Rose
# (Wikipedia entry.)
# 2) http://www.borrett.id.au/computing/petals-bg.htm
# (How Bill Gates coped with the Petals Around the Rose challenge.)
#!/bin/bash
# qky.sh
##############################################################
# QUACKEY: a somewhat simplified version of Perquackey [TM]. #
# #
# Author: Mendel Cooper <thegrendel.abs@gmail.com&gt; #
# version 0.1.02 03 May, 2008 #
# License: GPL3 #
##############################################################
WLIST=/usr/share/dict/word.lst
# ^^^^^^^^ Word list file found here.
# ASCII word list, one word per line, UNIX format.
# A suggested list is the script author's "yawl" word list package.
# http://bash.deta.in/yawl-0.3.2.tar.gz
# or
# http://ibiblio.org/pub/Linux/libs/yawl-0.3.2.tar.gz
NONCONS=0 # Word not constructable from letter set.
CONS=1 # Constructable.
SUCCESS=0
NG=1
FAILURE=''
NULL=0 # Zero out value of letter (if found).
MINWLEN=3 # Minimum word length.
MAXCAT=5 # Maximum number of words in a given category.
PENALTY=200 # General-purpose penalty for unacceptable words.
total=
E_DUP=70 # Duplicate word error.
TIMEOUT=10 # Time for word input.
NVLET=10 # 10 letters for non-vulnerable.
VULET=13 # 13 letters for vulnerable (not yet implemented!).
declare -a Words
declare -a Status
declare -a Score=( 0 0 0 0 0 0 0 0 0 0 0 )
letters=( a n s r t m l k p r b c i d s i d z e w u e t f
e y e r e f e g t g h h i t r s c i t i d i j a t a o l a
m n a n o v n w o s e l n o s p a q e e r a b r s a o d s
t g t i t l u e u v n e o x y m r k )
# Letter distribution table shamelessly borrowed from "Wordy" game,
#+ ca. 1992, written by a certain fine fellow named Mendel Cooper.
declare -a LS
numelements=${#letters[@]}
randseed="$1"
instructions ()
{
clear
echo "Welcome to QUACKEY, the anagramming word construction game."; echo
echo -n "Do you need instructions? (y/n) "; read ans
if [ "$ans" = "y" -o "$ans" = "Y" ]; then
clear
echo -e '\E[31;47m' # Red foreground. '\E[34;47m' for blue.
cat <<INSTRUCTION1
QUACKEY is a variant of Perquackey [TM].
The rules are the same, but the scoring is simplified
and plurals of previously played words are allowed.
"Vulnerable" play is not yet implemented,
but it is otherwise feature-complete.
As the game begins, the player gets 10 letters.
The object is to construct valid dictionary words
of at least 3-letter length from the letterset.
Each word-length category
-- 3-letter, 4-letter, 5-letter, ... --
fills up with the fifth word entered,
and no further words in that category are accepted.
The penalty for too-short (two-letter), duplicate, unconstructable,
and invalid (not in dictionary) words is -200. The same penalty applies
to attempts to enter a word in a filled-up category.
INSTRUCTION1
echo -n "Hit ENTER for next page of instructions. "; read az1
cat <<INSTRUCTION2
The scoring mostly corresponds to classic Perquackey:
The first 3-letter word scores 60, plus 10 for each additional one.
The first 4-letter word scores 120, plus 20 for each additional one.
The first 5-letter word scores 200, plus 50 for each additional one.
The first 6-letter word scores 300, plus 100 for each additional one.
The first 7-letter word scores 500, plus 150 for each additional one.
The first 8-letter word scores 750, plus 250 for each additional one.
The first 9-letter word scores 1000, plus 500 for each additional one.
The first 10-letter word scores 2000, plus 2000 for each additional one.
Category completion bonuses are:
3-letter words 100
4-letter words 200
5-letter words 400
6-letter words 800
7-letter words 2000
8-letter words 10000
This is a simplification of the absurdly baroque Perquackey bonus
scoring system.
INSTRUCTION2
echo -n "Hit ENTER for final page of instructions. "; read az1
cat <<INSTRUCTION3
Hitting just ENTER for a word entry ends the game.
Individual word entry is timed to a maximum of 10 seconds.
*** Timing out on an entry ends the game. ***
Aside from that, the game is untimed.
--------------------------------------------------
Game statistics are automatically saved to a file.
--------------------------------------------------
For competitive ("duplicate") play, a previous letterset
may be duplicated by repeating the script's random seed,
command-line parameter \$1.
For example, "qky 7633" specifies the letterset
c a d i f r h u s k ...
INSTRUCTION3
echo; echo -n "Hit ENTER to begin game. "; read az1
echo -e "\033[0m" # Turn off red.
else clear
fi
clear
}
seed_random ()
{ # Seed random number generator.
if [ -n "$randseed" ] # Can specify random seed.
then #+ for play in competitive mode.
# RANDOM="$randseed"
echo "RANDOM seed set to "$randseed""
else
randseed="$$" # Or get random seed from process ID.
echo "RANDOM seed not specified, set to Process ID of script ($$)."
fi
RANDOM="$randseed"
echo
}
get_letset ()
{
element=0
echo -n "Letterset:"
for lset in $(seq $NVLET)
do # Pick random letters to fill out letterset.
LS[element]="${letters[$((RANDOM%numelements))]}"
((element++))
done
echo
echo "${LS[@]}"
}
add_word ()
{
wrd="$1"
local idx=0
Status[0]=""
Status[3]=""
Status[4]=""
while [ "${Words[idx]}" != '' ]
do
if [ "${Words[idx]}" = "$wrd" ]
then
Status[3]="Duplicate-word-PENALTY"
let "Score[0]= 0 - $PENALTY"
let "Score[1]-=$PENALTY"
return $E_DUP
fi
((idx++))
done
Words[idx]="$wrd"
get_score
}
get_score()
{
local wlen=0
local score=0
local bonus=0
local first_word=0
local add_word=0
local numwords=0
wlen=${#wrd}
numwords=${Score[wlen]}
Score[2]=0
Status[4]="" # Initialize "bonus" to 0.
case "$wlen" in
3) first_word=60
add_word=10;;
4) first_word=120
add_word=20;;
5) first_word=200
add_word=50;;
6) first_word=300
add_word=100;;
7) first_word=500
add_word=150;;
8) first_word=750
add_word=250;;
9) first_word=1000
add_word=500;;
10) first_word=2000
add_word=2000;; # This category modified from original rules!
esac
((Score[wlen]++))
if [ ${Score[wlen]} -eq $MAXCAT ]
then # Category completion bonus scoring simplified!
case $wlen in
3 ) bonus=100;;
4 ) bonus=200;;
5 ) bonus=400;;
6 ) bonus=800;;
7 ) bonus=2000;;
8 ) bonus=10000;;
esac # Needn't worry about 9's and 10's.
Status[4]="Category-$wlen-completion***BONUS***"
Score[2]=$bonus
else
Status[4]="" # Erase it.
fi
let "score = $first_word + $add_word * $numwords"
if [ "$numwords" -eq 0 ]
then
Score[0]=$score
else
Score[0]=$add_word
fi # All this to distinguish last-word score
#+ from total running score.
let "Score[1] += ${Score[0]}"
let "Score[1] += ${Score[2]}"
}
get_word ()
{
local wrd=''
read -t $TIMEOUT wrd # Timed read.
echo $wrd
}
is_constructable ()
{ # This is the most complex and difficult-to-write function.
local -a local_LS=( "${LS[@]}" ) # Local copy of letter set.
local is_found=0
local idx=0
local pos
local strlen
local local_word=( "$1" )
strlen=${#local_word}
while [ "$idx" -lt "$strlen" ]
do
is_found=$(expr index "${local_LS[*]}" "${local_word:idx:1}")
if [ "$is_found" -eq "$NONCONS" ] # Not constructable!
then
echo "$FAILURE"; return
else
((pos = ($is_found - 1) / 2)) # Compensate for spaces betw. letters!
local_LS[pos]=$NULL # Zero out used letters.
((idx++)) # Bump index.
fi
done
echo "$SUCCESS"
return
}
is_valid ()
{ # Surprisingly easy to check if word in dictionary ...
fgrep -qw "$1" "$WLIST" # ... courtesy of 'grep' ...
echo $?
}
check_word ()
{
if [ -z "$1" ]
then
return
fi
Status[1]=""
Status[2]=""
Status[3]=""
Status[4]=""
iscons=$(is_constructable "$1")
if [ "$iscons" ]
then
Status[1]="constructable"
v=$(is_valid "$1")
if [ "$v" -eq "$SUCCESS" ]
then
Status[2]="valid"
strlen=${#1}
if [ ${Score[strlen]} -eq "$MAXCAT" ] # Category full!
then
Status[3]="Category-$strlen-overflow-PENALTY"
return $NG
fi
case "$strlen" in
1 | 2 )
Status[3]="Two-letter-word-PENALTY"
return $NG;;
* )
Status[3]=""
return $SUCCESS;;
esac
else
Status[3]="Not-valid-PENALTY"
return $NG
fi
else
Status[3]="Not-constructable-PENALTY"
return $NG
fi
### FIXME: Streamline the above code block.
}
display_words ()
{
local idx=0
local wlen0
clear
echo "Letterset: ${LS[@]}"
echo "Threes: Fours: Fives: Sixes: Sevens: Eights:"
echo "------------------------------------------------------------"
while [ "${Words[idx]}" != '' ]
do
wlen0=${#Words[idx]}
case "$wlen0" in
3) ;;
4) echo -n " " ;;
5) echo -n " " ;;
6) echo -n " " ;;
7) echo -n " " ;;
8) echo -n " " ;;
esac
echo "${Words[idx]}"
((idx++))
done
### FIXME: The word display is pretty crude.
}
play ()
{
word="Start game" # Dummy word, to start ...
while [ "$word" ] # If player just hits return (null word),
do #+ then game ends.
echo "$word: "${Status[@]}""
echo -n "Last score: [${Score[0]}] TOTAL score: [${Score[1]}]: Next word: "
total=${Score[1]}
word=$(get_word)
check_word "$word"
if [ "$?" -eq "$SUCCESS" ]
then
add_word "$word"
else
let "Score[0]= 0 - $PENALTY"
let "Score[1]-=$PENALTY"
fi
display_words
done # Exit game.
### FIXME: The play () function calls too many other functions.
### This verges on "spaghetti code" !!!
}
end_of_game ()
{ # Save and display stats.
#######################Autosave##########################
savefile=qky.save.$$
# ^^ PID of script
echo `date` &gt;&gt; $savefile
echo "Letterset # $randseed (random seed) "&gt;&gt; $savefile
echo -n "Letterset: " &gt;&gt; $savefile
echo "${LS[@]}" &gt;&gt; $savefile
echo "---------" &gt;&gt; $savefile
echo "Words constructed:" &gt;&gt; $savefile
echo "${Words[@]}" &gt;&gt; $savefile
echo &gt;&gt; $savefile
echo "Score: $total" &gt;&gt; $savefile
echo "Statistics for this round saved in \""$savefile"\""
#########################################################
echo "Score for this round: $total"
echo "Words: ${Words[@]}"
}
# ---------#
instructions
seed_random
get_letset
play
end_of_game
# ---------#
exit $?
# TODO:
#
# 1) Clean up code!
# 2) Prettify the display_words () function (maybe with widgets?).
# 3) Improve the time-out ... maybe change to untimed entry,
#+ but with a time limit for the overall round.
# 4) An on-screen countdown timer would be nice.
# 5) Implement "vulnerable" mode of play for compatibility with classic
#+ version of the game.
# 6) Improve save-to-file capability (and maybe make it optional).
# 7) Fix bugs!!!
# For more info, reference:
# http://bash.deta.in/qky.README.html
#!/bin/bash
# nim.sh: Game of Nim
# Author: Mendel Cooper
# Reldate: 15 July 2008
# License: GPL3
ROWS=5 # Five rows of pegs (or matchsticks).
WON=91 # Exit codes to keep track of wins/losses.
LOST=92 # Possibly useful if running in batch mode.
QUIT=99
peg_msg= # Peg/Pegs?
Rows=( 0 5 4 3 2 1 ) # Array holding play info.
# ${Rows[0]} holds total number of pegs, updated after each turn.
# Other array elements hold number of pegs in corresponding row.
instructions ()
{
clear
tput bold
echo "Welcome to the game of Nim."; echo
echo -n "Do you need instructions? (y/n) "; read ans
if [ "$ans" = "y" -o "$ans" = "Y" ]; then
clear
echo -e '\E[33;41m' # Yellow fg., over red bg.; bold.
cat <<INSTRUCTIONS
Nim is a game with roots in the distant past.
This particular variant starts with five rows of pegs.
1: | | | | |
2: | | | |
3: | | |
4: | |
5: |
The number at the left identifies the row.
The human player moves first, and alternates turns with the bot.
A turn consists of removing at least one peg from a single row.
It is permissable to remove ALL the pegs from a row.
For example, in row 2, above, the player can remove 1, 2, 3, or 4 pegs.
The player who removes the last peg loses.
The strategy consists of trying to be the one who removes
the next-to-last peg(s), leaving the loser with the final peg.
To exit the game early, hit ENTER during your turn.
INSTRUCTIONS
echo; echo -n "Hit ENTER to begin game. "; read azx
echo -e "\033[0m" # Restore display.
else tput sgr0; clear
fi
clear
}
tally_up ()
{
let "Rows[0] = ${Rows[1]} + ${Rows[2]} + ${Rows[3]} + ${Rows[4]} + \
${Rows[5]}" # Add up how many pegs remaining.
}
display ()
{
index=1 # Start with top row.
echo
while [ "$index" -le "$ROWS" ]
do
p=${Rows[index]}
echo -n "$index: " # Show row number.
# ------------------------------------------------
# Two concurrent inner loops.
indent=$index
while [ "$indent" -gt 0 ]
do
echo -n " " # Staggered rows.
((indent--)) # Spacing between pegs.
done
while [ "$p" -gt 0 ]
do
echo -n "| "
((p--))
done
# -----------------------------------------------
echo
((index++))
done
tally_up
rp=${Rows[0]}
if [ "$rp" -eq 1 ]
then
peg_msg=peg
final_msg="Game over."
else # Game not yet over . . .
peg_msg=pegs
final_msg="" # . . . So "final message" is blank.
fi
echo " $rp $peg_msg remaining."
echo " "$final_msg""
echo
}
player_move ()
{
echo "Your move:"
echo -n "Which row? "
while read idx
do # Validity check, etc.
if [ -z "$idx" ] # Hitting return quits.
then
echo "Premature exit."; echo
tput sgr0 # Restore display.
exit $QUIT
fi
if [ "$idx" -gt "$ROWS" -o "$idx" -lt 1 ] # Bounds check.
then
echo "Invalid row number!"
echo -n "Which row? "
else
break
fi
# TODO:
# Add check for non-numeric input.
# Also, script crashes on input outside of range of long double.
# Fix this.
done
echo -n "Remove how many? "
while read num
do # Validity check.
if [ -z "$num" ]
then
echo "Premature exit."; echo
tput sgr0 # Restore display.
exit $QUIT
fi
if [ "$num" -gt ${Rows[idx]} -o "$num" -lt 1 ]
then
echo "Cannot remove $num!"
echo -n "Remove how many? "
else
break
fi
done
# TODO:
# Add check for non-numeric input.
# Also, script crashes on input outside of range of long double.
# Fix this.
let "Rows[idx] -= $num"
display
tally_up
if [ ${Rows[0]} -eq 1 ]
then
echo " Human wins!"
echo " Congratulations!"
tput sgr0 # Restore display.
echo
exit $WON
fi
if [ ${Rows[0]} -eq 0 ]
then # Snatching defeat from the jaws of victory . . .
echo " Fool!"
echo " You just removed the last peg!"
echo " Bot wins!"
tput sgr0 # Restore display.
echo
exit $LOST
fi
}
bot_move ()
{
row_b=0
while [[ $row_b -eq 0 || ${Rows[row_b]} -eq 0 ]]
do
row_b=$RANDOM # Choose random row.
let "row_b %= $ROWS"
done
num_b=0
r0=${Rows[row_b]}
if [ "$r0" -eq 1 ]
then
num_b=1
else
let "num_b = $r0 - 1"
# Leave only a single peg in the row.
fi # Not a very strong strategy,
#+ but probably a bit better than totally random.
let "Rows[row_b] -= $num_b"
echo -n "Bot: "
echo "Removing from row $row_b ... "
if [ "$num_b" -eq 1 ]
then
peg_msg=peg
else
peg_msg=pegs
fi
echo " $num_b $peg_msg."
display
tally_up
if [ ${Rows[0]} -eq 1 ]
then
echo " Bot wins!"
tput sgr0 # Restore display.
exit $WON
fi
}
# ================================================== #
instructions # If human player needs them . . .
tput bold # Bold characters for easier viewing.
display # Show game board.
while [ true ] # Main loop.
do # Alternate human and bot turns.
player_move
bot_move
done
# ================================================== #
# Exercise:
# --------
# Improve the bot's strategy.
# There is, in fact, a Nim strategy that can force a win.
# See the Wikipedia article on Nim: http://en.wikipedia.org/wiki/Nim
# Recode the bot to use this strategy (rather difficult).
# Curiosities:
# -----------
# Nim played a prominent role in Alain Resnais' 1961 New Wave film,
#+ Last Year at Marienbad.
#
# In 1978, Leo Christopherson wrote an animated version of Nim,
#+ Android Nim, for the TRS-80 Model I.
#!/bin/sh
# sw.sh
# A command-line Stopwatch
# Author: Pádraig Brady
# http://www.pixelbeat.org/scripts/sw
# (Minor reformatting by ABS Guide author.)
# Used in ABS Guide with script author's permission.
# Notes:
# This script starts a few processes per lap, in addition to
# the shell loop processing, so the assumption is made that
# this takes an insignificant amount of time compared to
# the response time of humans (~.1s) (or the keyboard
# interrupt rate (~.05s)).
# '?' for splits must be entered twice if characters
# (erroneously) entered before it (on the same line).
# '?' since not generating a signal may be slightly delayed
# on heavily loaded systems.
# Lap timings on ubuntu may be slightly delayed due to:
# https://bugs.launchpad.net/bugs/62511
# Changes:
# V1.0, 23 Aug 2005, Initial release
# V1.1, 26 Jul 2007, Allow both splits and laps from single invocation.
# Only start timer after a key is pressed.
# Indicate lap number
# Cache programs at startup so there is less error
# due to startup delays.
# V1.2, 01 Aug 2007, Work around `date` commands that don't have
# nanoseconds.
# Use stty to change interrupt keys to space for
# laps etc.
# Ignore other input as it causes problems.
# V1.3, 01 Aug 2007, Testing release.
# V1.4, 02 Aug 2007, Various tweaks to get working under ubuntu
# and Mac OS X.
# V1.5, 27 Jun 2008, set LANG=C as got vague bug report about it.
export LANG=C
ulimit -c 0 # No coredumps from SIGQUIT.
trap '' TSTP # Ignore Ctrl-Z just in case.
save_tty=`stty -g` && trap "stty $save_tty" EXIT # Restore tty on exit.
stty quit ' ' # Space for laps rather than Ctrl-\.
stty eof '?' # ? for splits rather than Ctrl-D.
stty -echo # Don't echo input.
cache_progs() {
stty &gt; /dev/null
date &gt; /dev/null
grep . < /dev/null
(echo "import time" | python) 2&gt; /dev/null
bc < /dev/null
sed '' < /dev/null
printf '1' &gt; /dev/null
/usr/bin/time false 2&gt; /dev/null
cat < /dev/null
}
cache_progs # To minimise startup delay.
date +%s.%N | grep -qF 'N' && use_python=1 # If `date` lacks nanoseconds.
now() {
if [ "$use_python" ]; then
echo "import time; print time.time()" 2&gt;/dev/null | python
else
printf "%.2f" `date +%s.%N`
fi
}
fmt_seconds() {
seconds=$1
mins=`echo $seconds/60 | bc`
if [ "$mins" != "0" ]; then
seconds=`echo "$seconds - ($mins*60)" | bc`
echo "$mins:$seconds"
else
echo "$seconds"
fi
}
total() {
end=`now`
total=`echo "$end - $start" | bc`
fmt_seconds $total
}
stop() {
[ "$lapped" ] && lap "$laptime" "display"
total
exit
}
lap() {
laptime=`echo "$1" | sed -n 's/.*real[^0-9.]*\(.*\)/\1/p'`
[ ! "$laptime" -o "$laptime" = "0.00" ] && return
# Signals too frequent.
laptotal=`echo $laptime+0$laptotal | bc`
if [ "$2" = "display" ]; then
lapcount=`echo 0$lapcount+1 | bc`
laptime=`fmt_seconds $laptotal`
echo $laptime "($lapcount)"
lapped="true"
laptotal="0"
fi
}
echo -n "Space for lap | ? for split | Ctrl-C to stop | Space to start..."&gt;&2
while true; do
trap true INT QUIT # Set signal handlers.
laptime=`/usr/bin/time -p 2&gt;&1 cat &gt;/dev/null`
ret=$?
trap '' INT QUIT # Ignore signals within this script.
if [ $ret -eq 1 -o $ret -eq 2 -o $ret -eq 130 ]; then # SIGINT = stop
[ ! "$start" ] && { echo &gt;&2; exit; }
stop
elif [ $ret -eq 3 -o $ret -eq 131 ]; then # SIGQUIT = lap
if [ ! "$start" ]; then
start=`now` || exit 1
echo &gt;&2
continue
fi
lap "$laptime" "display"
else # eof = split
[ ! "$start" ] && continue
total
lap "$laptime" # Update laptotal.
fi
done
exit $?
#!/bin/bash
# homework.sh: All-purpose homework assignment solution.
# Author: M. Leo Cooper
# If you substitute your own name as author, then it is plagiarism,
#+ possibly a lesser sin than cheating on your homework!
# License: Public Domain
# This script may be turned in to your instructor
#+ in fulfillment of ALL shell scripting homework assignments.
# It's sparsely commented, but you, the student, can easily remedy that.
# The script author repudiates all responsibility!
DLA=1
P1=2
P2=4
P3=7
PP1=0
PP2=8
MAXL=9
E_LZY=99
declare -a L
L[0]="3 4 0 17 29 8 13 18 19 17 20 2 19 14 17 28"
L[1]="8 29 12 14 18 19 29 4 12 15 7 0 19 8 2 0 11 11 24 29 17 4 6 17 4 19"
L[2]="29 19 7 0 19 29 8 29 7 0 21 4 29 13 4 6 11 4 2 19 4 3"
L[3]="19 14 29 2 14 12 15 11 4 19 4 29 19 7 8 18 29"
L[4]="18 2 7 14 14 11 22 14 17 10 29 0 18 18 8 6 13 12 4 13 19 26"
L[5]="15 11 4 0 18 4 29 0 2 2 4 15 19 29 12 24 29 7 20 12 1 11 4 29"
L[6]="4 23 2 20 18 4 29 14 5 29 4 6 17 4 6 8 14 20 18 29"
L[7]="11 0 25 8 13 4 18 18 27"
L[8]="0 13 3 29 6 17 0 3 4 29 12 4 29 0 2 2 14 17 3 8 13 6 11 24 26"
L[9]="19 7 0 13 10 29 24 14 20 26"
declare -a \
alph=( A B C D E F G H I J K L M N O P Q R S T U V W X Y Z . , : ' ' )
pt_lt ()
{
echo -n "${alph[$1]}"
echo -n -e "\a"
sleep $DLA
}
b_r ()
{
echo -e '\E[31;48m\033[1m'
}
cr ()
{
echo -e "\a"
sleep $DLA
}
restore ()
{
echo -e '\033[0m' # Bold off.
tput sgr0 # Normal.
}
p_l ()
{
for ltr in $1
do
pt_lt "$ltr"
done
}
# ----------------------
b_r
for i in $(seq 0 $MAXL)
do
p_l "${L[i]}"
if [[ "$i" -eq "$P1" || "$i" -eq "$P2" || "$i" -eq "$P3" ]]
then
cr
elif [[ "$i" -eq "$PP1" || "$i" -eq "$PP2" ]]
then
cr; cr
fi
done
restore
# ----------------------
echo
exit $E_LZY
# A typical example of an obfuscated script that is difficult
#+ to understand, and frustrating to maintain.
# In your career as a sysadmin, you'll run into these critters
#+ all too often.
#!/bin/bash
# ktour.sh
# author: mendel cooper
# reldate: 12 Jan 2009
# license: public domain
# (Not much sense GPLing something that's pretty much in the common
#+ domain anyhow.)
###################################################################
# The Knight's Tour, a classic problem. #
# ===================================== #
# The knight must move onto every square of the chess board, #
# but cannot revisit any square he has already visited. #
# #
# And just why is Sir Knight unwelcome for a return visit? #
# Could it be that he has a habit of partying into the wee hours #
#+ of the morning? #
# Possibly he leaves pizza crusts in the bed, empty beer bottles #
#+ all over the floor, and clogs the plumbing. . . . #
# #
# ------------------------------------------------------------- #
# #
# Usage: ktour.sh [start-square] [stupid] #
# #
# Note that start-square can be a square number #
#+ in the range 0 - 63 ... or #
# a square designator in conventional chess notation, #
# such as a1, f5, h3, etc. #
# #
# If start-square-number not supplied, #
#+ then starts on a random square somewhere on the board. #
# #
# "stupid" as second parameter sets the stupid strategy. #
# #
# Examples: #
# ktour.sh 23 starts on square #23 (h3) #
# ktour.sh g6 stupid starts on square #46, #
# using "stupid" (non-Warnsdorff) strategy. #
###################################################################
DEBUG= # Set this to echo debugging info to stdout.
SUCCESS=0
FAIL=99
BADMOVE=-999
FAILURE=1
LINELEN=21 # How many moves to display per line.
# ---------------------------------------- #
# Board array params
ROWS=8 # 8 x 8 board.
COLS=8
let "SQUARES = $ROWS * $COLS"
let "MAX = $SQUARES - 1"
MIN=0
# 64 squares on board, indexed from 0 to 63.
VISITED=1
UNVISITED=-1
UNVSYM="##"
# ---------------------------------------- #
# Global variables.
startpos= # Starting position (square #, 0 - 63).
currpos= # Current position.
movenum= # Move number.
CRITPOS=37 # Have to patch for f5 starting position!
declare -i board
# Use a one-dimensional array to simulate a two-dimensional one.
# This can make life difficult and result in ugly kludges; see below.
declare -i moves # Offsets from current knight position.
initialize_board ()
{
local idx
for idx in {0..63}
do
board[$idx]=$UNVISITED
done
}
print_board ()
{
local idx
echo " _____________________________________"
for row in {7..0} # Reverse order of rows ...
do #+ so it prints in chessboard order.
let "rownum = $row + 1" # Start numbering rows at 1.
echo -n "$rownum |" # Mark board edge with border and
for column in {0..7} #+ "algebraic notation."
do
let "idx = $ROWS*$row + $column"
if [ ${board[idx]} -eq $UNVISITED ]
then
echo -n "$UNVSYM " ##
else # Mark square with move number.
printf "%02d " "${board[idx]}"; echo -n " "
fi
done
echo -e -n "\b\b\b|" # \b is a backspace.
echo # -e enables echoing escaped chars.
done
echo " -------------------------------------"
echo " a b c d e f g h"
}
failure()
{ # Whine, then bail out.
echo
print_board
echo
echo " Waah!!! Ran out of squares to move to!"
echo -n " Knight's Tour attempt ended"
echo " on $(to_algebraic $currpos) [square #$currpos]"
echo " after just $movenum moves!"
echo
exit $FAIL
}
xlat_coords () # Translate x/y coordinates to board position
{ #+ (board-array element #).
# For user input of starting board position as x/y coords.
# This function not used in initial release of ktour.sh.
# May be used in an updated version, for compatibility with
#+ standard implementation of the Knight's Tour in C, Python, etc.
if [ -z "$1" -o -z "$2" ]
then
return $FAIL
fi
local xc=$1
local yc=$2
let "board_index = $xc * $ROWS + yc"
if [ $board_index -lt $MIN -o $board_index -gt $MAX ]
then
return $FAIL # Strayed off the board!
else
return $board_index
fi
}
to_algebraic () # Translate board position (board-array element #)
{ #+ to standard algebraic notation used by chess players.
if [ -z "$1" ]
then
return $FAIL
fi
local element_no=$1 # Numerical board position.
local col_arr=( a b c d e f g h )
local row_arr=( 1 2 3 4 5 6 7 8 )
let "row_no = $element_no / $ROWS"
let "col_no = $element_no % $ROWS"
t1=${col_arr[col_no]}; t2=${row_arr[row_no]}
local apos=$t1$t2 # Concatenate.
echo $apos
}
from_algebraic () # Translate standard algebraic chess notation
{ #+ to numerical board position (board-array element #).
# Or recognize numerical input & return it unchanged.
if [ -z "$1" ]
then
return $FAIL
fi # If no command-line arg, then will default to random start pos.
local ix
local ix_count=0
local b_index # Board index [0-63]
local alpos="$1"
arow=${alpos:0:1} # position = 0, length = 1
acol=${alpos:1:1}
if [[ $arow =~ [[:digit:]] ]] # Numerical input?
then # POSIX char class
if [[ $acol =~ [[:alpha:]] ]] # Number followed by a letter? Illegal!
then return $FAIL
else if [ $alpos -gt $MAX ] # Off board?
then return $FAIL
else return $alpos # Return digit(s) unchanged . . .
fi #+ if within range.
fi
fi
if [[ $acol -eq $MIN || $acol -gt $ROWS ]]
then # Outside of range 1 - 8?
return $FAIL
fi
for ix in a b c d e f g h
do # Convert column letter to column number.
if [ "$arow" = "$ix" ]
then
break
fi
((ix_count++)) # Find index count.
done
((acol--)) # Decrementing converts to zero-based array.
let "b_index = $ix_count + $acol * $ROWS"
if [ $b_index -gt $MAX ] # Off board?
then
return $FAIL
fi
return $b_index
}
generate_moves () # Calculate all valid knight moves,
{ #+ relative to current position ($1),
#+ and store in ${moves} array.
local kt_hop=1 # One square :: short leg of knight move.
local kt_skip=2 # Two squares :: long leg of knight move.
local valmov=0 # Valid moves.
local row_pos; let "row_pos = $1 % $COLS"
let "move1 = -$kt_skip + $ROWS" # 2 sideways to-the-left, 1 up
if [[ `expr $row_pos - $kt_skip` -lt $MIN ]] # An ugly, ugly kludge!
then # Can't move off board.
move1=$BADMOVE # Not even temporarily.
else
((valmov++))
fi
let "move2 = -$kt_hop + $kt_skip * $ROWS" # 1 sideways to-the-left, 2 up
if [[ `expr $row_pos - $kt_hop` -lt $MIN ]] # Kludge continued ...
then
move2=$BADMOVE
else
((valmov++))
fi
let "move3 = $kt_hop + $kt_skip * $ROWS" # 1 sideways to-the-right, 2 up
if [[ `expr $row_pos + $kt_hop` -ge $COLS ]]
then
move3=$BADMOVE
else
((valmov++))
fi
let "move4 = $kt_skip + $ROWS" # 2 sideways to-the-right, 1 up
if [[ `expr $row_pos + $kt_skip` -ge $COLS ]]
then
move4=$BADMOVE
else
((valmov++))
fi
let "move5 = $kt_skip - $ROWS" # 2 sideways to-the-right, 1 dn
if [[ `expr $row_pos + $kt_skip` -ge $COLS ]]
then
move5=$BADMOVE
else
((valmov++))
fi
let "move6 = $kt_hop - $kt_skip * $ROWS" # 1 sideways to-the-right, 2 dn
if [[ `expr $row_pos + $kt_hop` -ge $COLS ]]
then
move6=$BADMOVE
else
((valmov++))
fi
let "move7 = -$kt_hop - $kt_skip * $ROWS" # 1 sideways to-the-left, 2 dn
if [[ `expr $row_pos - $kt_hop` -lt $MIN ]]
then
move7=$BADMOVE
else
((valmov++))
fi
let "move8 = -$kt_skip - $ROWS" # 2 sideways to-the-left, 1 dn
if [[ `expr $row_pos - $kt_skip` -lt $MIN ]]
then
move8=$BADMOVE
else
((valmov++))
fi # There must be a better way to do this.
local m=( $valmov $move1 $move2 $move3 $move4 $move5 $move6 $move7 $move8 )
# ${moves[0]} = number of valid moves.
# ${moves[1]} ... ${moves[8]} = possible moves.
echo "${m[*]}" # Elements of array to stdout for capture in a var.
}
is_on_board () # Is position actually on the board?
{
if [[ "$1" -lt "$MIN" || "$1" -gt "$MAX" ]]
then
return $FAILURE
else
return $SUCCESS
fi
}
do_move () # Move the knight!
{
local valid_moves=0
local aapos
currposl="$1"
lmin=$ROWS
iex=0
squarel=
mpm=
mov=
declare -a p_moves
########################## DECIDE-MOVE #############################
if [ $startpos -ne $CRITPOS ]
then # CRITPOS = square #37
decide_move
else # Needs a special patch for startpos=37 !!!
decide_move_patched # Why this particular move and no other ???
fi
####################################################################
(( ++movenum )) # Increment move count.
let "square = $currposl + ${moves[iex]}"
################## DEBUG ###############
if [ "$DEBUG" ]
then debug # Echo debugging information.
fi
##############################################
if [[ "$square" -gt $MAX || "$square" -lt $MIN ||
${board[square]} -ne $UNVISITED ]]
then
(( --movenum )) # Decrement move count,
echo "RAN OUT OF SQUARES!!!" #+ since previous one was invalid.
return $FAIL
fi
board[square]=$movenum
currpos=$square # Update current position.
((valid_moves++)); # moves[0]=$valid_moves
aapos=$(to_algebraic $square)
echo -n "$aapos "
test $(( $Moves % $LINELEN )) -eq 0 && echo
# Print LINELEN=21 moves per line. A valid tour shows 3 complete lines.
return $valid_moves # Found a square to move to!
}
do_move_stupid() # Dingbat algorithm,
{ #+ courtesy of script author, *not* Warnsdorff.
local valid_moves=0
local movloc
local squareloc
local aapos
local cposloc="$1"
for movloc in {1..8}
do # Move to first-found unvisited square.
let "squareloc = $cposloc + ${moves[movloc]}"
is_on_board $squareloc
if [ $? -eq $SUCCESS ] && [ ${board[squareloc]} -eq $UNVISITED ]
then # Add conditions to above if-test to improve algorithm.
(( ++movenum ))
board[squareloc]=$movenum
currpos=$squareloc # Update current position.
((valid_moves++)); # moves[0]=$valid_moves
aapos=$(to_algebraic $squareloc)
echo -n "$aapos "
test $(( $Moves % $LINELEN )) -eq 0 && echo # Print 21 moves/line.
return $valid_moves # Found a square to move to!
fi
done
return $FAIL
# If no square found in all 8 loop iterations,
#+ then Knight's Tour attempt ends in failure.
# Dingbat algorithm will typically fail after about 30 - 40 moves,
#+ but executes _much_ faster than Warnsdorff's in do_move() function.
}
decide_move () # Which move will we make?
{ # But, fails on startpos=37 !!!
for mov in {1..8}
do
let "squarel = $currposl + ${moves[mov]}"
is_on_board $squarel
if [[ $? -eq $SUCCESS && ${board[squarel]} -eq $UNVISITED ]]
then # Find accessible square with least possible future moves.
# This is Warnsdorff's algorithm.
# What happens is that the knight wanders toward the outer edge
#+ of the board, then pretty much spirals inward.
# Given two or more possible moves with same value of
#+ least-possible-future-moves, this implementation chooses
#+ the _first_ of those moves.
# This means that there is not necessarily a unique solution
#+ for any given starting position.
possible_moves $squarel
mpm=$?
p_moves[mov]=$mpm
if [ $mpm -lt $lmin ] # If less than previous minimum ...
then # ^^
lmin=$mpm # Update minimum.
iex=$mov # Save index.
fi
fi
done
}
decide_move_patched () # Decide which move to make,
{ # ^^^^^^^ #+ but only if startpos=37 !!!
for mov in {1..8}
do
let "squarel = $currposl + ${moves[mov]}"
is_on_board $squarel
if [[ $? -eq $SUCCESS && ${board[squarel]} -eq $UNVISITED ]]
then
possible_moves $squarel
mpm=$?
p_moves[mov]=$mpm
if [ $mpm -le $lmin ] # If less-than-or equal to prev. minimum!
then # ^^
lmin=$mpm
iex=$mov
fi
fi
done # There has to be a better way to do this.
}
possible_moves () # Calculate number of possible moves,
{ #+ given the current position.
if [ -z "$1" ]
then
return $FAIL
fi
local curr_pos=$1
local valid_movl=0
local icx=0
local movl
local sq
declare -a movesloc
movesloc=( $(generate_moves $curr_pos) )
for movl in {1..8}
do
let "sq = $curr_pos + ${movesloc[movl]}"
is_on_board $sq
if [ $? -eq $SUCCESS ] && [ ${board[sq]} -eq $UNVISITED ]
then
((valid_movl++));
fi
done
return $valid_movl # Found a square to move to!
}
strategy ()
{
echo
if [ -n "$STUPID" ]
then
for Moves in {1..63}
do
cposl=$1
moves=( $(generate_moves $currpos) )
do_move_stupid "$currpos"
if [ $? -eq $FAIL ]
then
failure
fi
done
fi
# Don't need an "else" clause here,
#+ because Stupid Strategy will always fail and exit!
for Moves in {1..63}
do
cposl=$1
moves=( $(generate_moves $currpos) )
do_move "$currpos"
if [ $? -eq $FAIL ]
then
failure
fi
done
# Could have condensed above two do-loops into a single one,
echo #+ but this would have slowed execution.
print_board
echo
echo "Knight's Tour ends on $(to_algebraic $currpos) [square #$currpos]."
return $SUCCESS
}
debug ()
{ # Enable this by setting DEBUG=1 near beginning of script.
local n
echo "================================="
echo " At move number $movenum:"
echo " *** possible moves = $mpm ***"
# echo "### square = $square ###"
echo "lmin = $lmin"
echo "${moves[@]}"
for n in {1..8}
do
echo -n "($n):${p_moves[n]} "
done
echo
echo "iex = $iex :: moves[iex] = ${moves[iex]}"
echo "square = $square"
echo "================================="
echo
} # Gives pretty complete status after ea. move.
# =============================================================== #
# int main () {
from_algebraic "$1"
startpos=$?
if [ "$startpos" -eq "$FAIL" ] # Okay even if no $1.
then # ^^^^^^^^^^^ Okay even if input -lt 0.
echo "No starting square specified (or illegal input)."
let "startpos = $RANDOM % $SQUARES" # 0 - 63 permissable range.
fi
if [ "$2" = "stupid" ]
then
STUPID=1
echo -n " ### Stupid Strategy ###"
else
STUPID=''
echo -n " *** Warnsdorff's Algorithm ***"
fi
initialize_board
movenum=0
board[startpos]=$movenum # Mark each board square with move number.
currpos=$startpos
algpos=$(to_algebraic $startpos)
echo; echo "Starting from $algpos [square #$startpos] ..."; echo
echo -n "Moves:"
strategy "$currpos"
echo
exit 0 # return 0;
# } # End of main() pseudo-function.
# =============================================================== #
# Exercises:
# ---------
#
# 1) Extend this example to a 10 x 10 board or larger.
# 2) Improve the "stupid strategy" by modifying the
# do_move_stupid function.
# Hint: Prevent straying into corner squares in early moves
# (the exact opposite of Warnsdorff's algorithm!).
# 3) This script could stand considerable improvement and
# streamlining, especially in the poorly-written
# generate_moves() function
# and in the DECIDE-MOVE patch in the do_move() function.
# Must figure out why standard algorithm fails for startpos=37 ...
#+ but _not_ on any other, including symmetrical startpos=26.
# Possibly, when calculating possible moves, counts the move back
#+ to the originating square. If so, it might be a relatively easy fix.
#!/bin/bash
# msquare.sh
# Magic Square generator (odd-order squares only!)
# Author: mendel cooper
# reldate: 19 Jan. 2009
# License: Public Domain
# A C-program by the very talented Kwon Young Shin inspired this script.
# http://user.chollian.net/~brainstm/MagicSquare.htm
# Definition: A "magic square" is a two-dimensional array
# of integers in which all the rows, columns,
# and *long* diagonals add up to the same number.
# Being "square," the array has the same number
# of rows and columns. That number is the "order."
# An example of a magic square of order 3 is:
# 8 1 6
# 3 5 7
# 4 9 2
# All the rows, columns, and the two long diagonals add up to 15.
# Globals
EVEN=2
MAXSIZE=31 # 31 rows x 31 cols.
E_usage=90 # Invocation error.
dimension=
declare -i square
usage_message ()
{
echo "Usage: $0 order"
echo " ... where \"order\" (square size) is an ODD integer"
echo " in the range 3 - 31."
# Actually works for squares up to order 159,
#+ but large squares will not display pretty-printed in a term window.
# Try increasing MAXSIZE, above.
exit $E_usage
}
calculate () # Here's where the actual work gets done.
{
local row col index dimadj j k cell_val=1
dimension=$1
let "dimadj = $dimension * 3"; let "dimadj /= 2" # x 1.5, then truncate.
for ((j=0; j < dimension; j++))
do
for ((k=0; k < dimension; k++))
do # Calculate indices, then convert to 1-dim. array index.
# Bash doesn't support multidimensional arrays. Pity.
let "col = $k - $j + $dimadj"; let "col %= $dimension"
let "row = $j * 2 - $k + $dimension"; let "row %= $dimension"
let "index = $row*($dimension) + $col"
square[$index]=cell_val; ((cell_val++))
done
done
} # Plain math, visualization not required.
print_square () # Output square, one row at a time.
{
local row col idx d1
let "d1 = $dimension - 1" # Adjust for zero-indexed array.
for row in $(seq 0 $d1)
do
for col in $(seq 0 $d1)
do
let "idx = $row * $dimension + $col"
printf "%3d " "${square[idx]}"; echo -n " "
done # Displays up to 13th order neatly in 80-column term window.
echo # Newline after each row.
done
}
#################################################
if [[ -z "$1" ]] || [[ "$1" -gt $MAXSIZE ]]
then
usage_message
fi
let "test_even = $1 % $EVEN"
if [ $test_even -eq 0 ]
then # Can't handle even-order squares.
usage_message
fi
calculate $1
print_square # echo "${square[@]}" # DEBUG
exit $?
#################################################
# Exercises:
# ---------
# 1) Add a function to calculate the sum of each row, column,
# and *long* diagonal. The sums must match.
# This is the "magic constant" of that particular order square.
# 2) Have the print_square function auto-calculate how much space
# to allot between square elements for optimized display.
# This might require parameterizing the "printf" line.
# 3) Add appropriate functions for generating magic squares
# with an *even* number of rows/columns.
# This is non-trivial(!).
# See the URL for Kwon Young Shin, above, for help.
#!/bin/bash
# fifteen.sh
# Classic "Fifteen Puzzle"
# Author: Antonio Macchi
# Lightly edited and commented by ABS Guide author.
# Used in ABS Guide with permission. (Thanks!)
# The invention of the Fifteen Puzzle is attributed to either
#+ Sam Loyd or Noyes Palmer Chapman.
# The puzzle was wildly popular in the late 19th-century.
# Object: Rearrange the numbers so they read in order,
#+ from 1 - 15: ________________
# | 1 2 3 4 |
# | 5 6 7 8 |
# | 9 10 11 12 |
# | 13 14 15 |
# ----------------
#######################
# Constants #
SQUARES=16 #
FAIL=70 #
E_PREMATURE_EXIT=80 #
#######################
########
# Data #
########
Puzzle=( 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 " " )
#############
# Functions #
#############
function swap
{
local tmp
tmp=${Puzzle[$1]}
Puzzle[$1]=${Puzzle[$2]}
Puzzle[$2]=$tmp
}
function Jumble
{ # Scramble the pieces at beginning of round.
local i pos1 pos2
for i in {1..100}
do
pos1=$(( $RANDOM % $SQUARES))
pos2=$(( $RANDOM % $SQUARES ))
swap $pos1 $pos2
done
}
function PrintPuzzle
{
local i1 i2 puzpos
puzpos=0
clear
echo "Enter quit to exit."; echo # Better that than Ctl-C.
echo ",----.----.----.----." # Top border.
for i1 in {1..4}
do
for i2 in {1..4}
do
printf "| %2s " "${Puzzle[$puzpos]}"
(( puzpos++ ))
done
echo "|" # Right-side border.
test $i1 = 4 || echo "+----+----+----+----+"
done
echo "'----'----'----'----'" # Bottom border.
}
function GetNum
{ # Test for valid input.
local puznum garbage
while true
do
echo "Moves: $moves" # Also counts invalid moves.
read -p "Number to move: " puznum garbage
if [ "$puznum" = "quit" ]; then echo; exit $E_PREMATURE_EXIT; fi
test -z "$puznum" -o -n "${puznum//[0-9]/}" && continue
test $puznum -gt 0 -a $puznum -lt $SQUARES && break
done
return $puznum
}
function GetPosFromNum
{ # $1 = puzzle-number
local puzpos
for puzpos in {0..15}
do
test "${Puzzle[$puzpos]}" = "$1" && break
done
return $puzpos
}
function Move
{ # $1=Puzzle-pos
test $1 -gt 3 && test "${Puzzle[$(( $1 - 4 ))]}" = " "\
&& swap $1 $(( $1 - 4 )) && return 0
test $(( $1%4 )) -ne 3 && test "${Puzzle[$(( $1 + 1 ))]}" = " "\
&& swap $1 $(( $1 + 1 )) && return 0
test $1 -lt 12 && test "${Puzzle[$(( $1 + 4 ))]}" = " "\
&& swap $1 $(( $1 + 4 )) && return 0
test $(( $1%4 )) -ne 0 && test "${Puzzle[$(( $1 - 1 ))]}" = " " &&\
swap $1 $(( $1 - 1 )) && return 0
return 1
}
function Solved
{
local pos
for pos in {0..14}
do
test "${Puzzle[$pos]}" = $(( $pos + 1 )) || return $FAIL
# Check whether number in each square = square number.
done
return 0 # Successful solution.
}
################### MAIN () #######################{
moves=0
Jumble
while true # Loop continuously until puzzle solved.
do
echo; echo
PrintPuzzle
echo
while true
do
GetNum
puznum=$?
GetPosFromNum $puznum
puzpos=$?
((moves++))
Move $puzpos && break
done
Solved && break
done
echo;echo
PrintPuzzle
echo; echo "BRAVO!"; echo
exit 0
###################################################}
# Exercise:
# --------
# Rewrite the script to display the letters A - O,
#+ rather than the numbers 1 - 15.
#! /bin/bash
# The Towers Of Hanoi
# Original script (hanoi.bash) copyright (C) 2000 Amit Singh.
# All Rights Reserved.
# http://hanoi.kernelthread.com
# hanoi2.bash
# Version 2.00: modded for ASCII-graphic display.
# Version 2.01: fixed no command-line param bug.
# Uses code contributed by Antonio Macchi,
#+ with heavy editing by ABS Guide author.
# This variant falls under the original copyright, see above.
# Used in ABS Guide with Amit Singh's permission (thanks!).
### Variables && sanity check ###
E_NOPARAM=86
E_BADPARAM=87 # Illegal no. of disks passed to script.
E_NOEXIT=88
DISKS=${1:-$E_NOPARAM} # Must specify how many disks.
Moves=0
MWIDTH=7
MARGIN=2
# Arbitrary "magic" constants; work okay for relatively small # of disks.
# BASEWIDTH=51 # Original code.
let "basewidth = $MWIDTH * $DISKS + $MARGIN" # "Base" beneath rods.
# Above "algorithm" could likely stand improvement.
### Display variables ###
let "disks1 = $DISKS - 1"
let "spaces1 = $DISKS"
let "spaces2 = 2 * $DISKS"
let "lastmove_t = $DISKS - 1" # Final move?
declare -a Rod1 Rod2 Rod3
### ######################### ###
function repeat { # $1=char $2=number of repetitions
local n # Repeat-print a character.
for (( n=0; n<$2; n++ )); do
echo -n "$1"
done
}
function FromRod {
local rod summit weight sequence
while true; do
rod=$1
test ${rod/[^123]/} || continue
sequence=$(echo $(seq 0 $disks1 | tac))
for summit in $sequence; do
eval weight=\${Rod${rod}[$summit]}
test $weight -ne 0 &&
{ echo "$rod $summit $weight"; return; }
done
done
}
function ToRod { # $1=previous (FromRod) weight
local rod firstfree weight sequence
while true; do
rod=$2
test ${rod/[^123]} || continue
sequence=$(echo $(seq 0 $disks1 | tac))
for firstfree in $sequence; do
eval weight=\${Rod${rod}[$firstfree]}
test $weight -gt 0 && { (( firstfree++ )); break; }
done
test $weight -gt $1 -o $firstfree = 0 &&
{ echo "$rod $firstfree"; return; }
done
}
function PrintRods {
local disk rod empty fill sp sequence
repeat " " $spaces1
echo -n "|"
repeat " " $spaces2
echo -n "|"
repeat " " $spaces2
echo "|"
sequence=$(echo $(seq 0 $disks1 | tac))
for disk in $sequence; do
for rod in {1..3}; do
eval empty=$(( $DISKS - (Rod${rod}[$disk] / 2) ))
eval fill=\${Rod${rod}[$disk]}
repeat " " $empty
test $fill -gt 0 && repeat "*" $fill || echo -n "|"
repeat " " $empty
done
echo
done
repeat "=" $basewidth # Print "base" beneath rods.
echo
}
display ()
{
echo
PrintRods
# Get rod-number, summit and weight
first=( `FromRod $1` )
eval Rod${first[0]}[${first[1]}]=0
# Get rod-number and first-free position
second=( `ToRod ${first[2]} $2` )
eval Rod${second[0]}[${second[1]}]=${first[2]}
echo; echo; echo
if [ "${Rod3[lastmove_t]}" = 1 ]
then # Last move? If yes, then display final position.
echo "+ Final Position: $Moves moves"; echo
PrintRods
fi
}
# From here down, almost the same as original (hanoi.bash) script.
dohanoi() { # Recursive function.
case $1 in
0)
;;
*)
dohanoi "$(($1-1))" $2 $4 $3
if [ "$Moves" -ne 0 ]
then
echo "+ Position after move $Moves"
fi
((Moves++))
echo -n " Next move will be: "
echo $2 "--&gt;" $3
display $2 $3
dohanoi "$(($1-1))" $4 $3 $2
;;
esac
}
setup_arrays ()
{
local dim n elem
let "dim1 = $1 - 1"
elem=$dim1
for n in $(seq 0 $dim1)
do
let "Rod1[$elem] = 2 * $n + 1"
Rod2[$n]=0
Rod3[$n]=0
((elem--))
done
}
### Main ###
setup_arrays $DISKS
echo; echo "+ Start Position"
case $# in
1) case $(($1&gt;0)) in # Must have at least one disk.
1)
disks=$1
dohanoi $1 1 3 2
# Total moves = 2^n - 1, where n = number of disks.
echo
exit 0;
;;
*)
echo "$0: Illegal value for number of disks";
exit $E_BADPARAM;
;;
esac
;;
*)
clear
echo "usage: $0 N"
echo " Where \"N\" is the number of disks."
exit $E_NOPARAM;
;;
esac
exit $E_NOEXIT # Shouldn't exit here.
# Note:
# Redirect script output to a file, otherwise it scrolls off display.
#! /bin/bash
# The Towers Of Hanoi
# Original script (hanoi.bash) copyright (C) 2000 Amit Singh.
# All Rights Reserved.
# http://hanoi.kernelthread.com
# hanoi2.bash
# Version 2: modded for ASCII-graphic display.
# Uses code contributed by Antonio Macchi,
#+ with heavy editing by ABS Guide author.
# This variant also falls under the original copyright, see above.
# Used in ABS Guide with Amit Singh's permission (thanks!).
# Variables #
E_NOPARAM=86
E_BADPARAM=87 # Illegal no. of disks passed to script.
E_NOEXIT=88
DELAY=2 # Interval, in seconds, between moves. Change, if desired.
DISKS=$1
Moves=0
MWIDTH=7
MARGIN=2
# Arbitrary "magic" constants, work okay for relatively small # of disks.
# BASEWIDTH=51 # Original code.
let "basewidth = $MWIDTH * $DISKS + $MARGIN" # "Base" beneath rods.
# Above "algorithm" could likely stand improvement.
# Display variables.
let "disks1 = $DISKS - 1"
let "spaces1 = $DISKS"
let "spaces2 = 2 * $DISKS"
let "lastmove_t = $DISKS - 1" # Final move?
declare -a Rod1 Rod2 Rod3
#################
function repeat { # $1=char $2=number of repetitions
local n # Repeat-print a character.
for (( n=0; n<$2; n++ )); do
echo -n "$1"
done
}
function FromRod {
local rod summit weight sequence
while true; do
rod=$1
test ${rod/[^123]/} || continue
sequence=$(echo $(seq 0 $disks1 | tac))
for summit in $sequence; do
eval weight=\${Rod${rod}[$summit]}
test $weight -ne 0 &&
{ echo "$rod $summit $weight"; return; }
done
done
}
function ToRod { # $1=previous (FromRod) weight
local rod firstfree weight sequence
while true; do
rod=$2
test ${rod/[^123]} || continue
sequence=$(echo $(seq 0 $disks1 | tac))
for firstfree in $sequence; do
eval weight=\${Rod${rod}[$firstfree]}
test $weight -gt 0 && { (( firstfree++ )); break; }
done
test $weight -gt $1 -o $firstfree = 0 &&
{ echo "$rod $firstfree"; return; }
done
}
function PrintRods {
local disk rod empty fill sp sequence
tput cup 5 0
repeat " " $spaces1
echo -n "|"
repeat " " $spaces2
echo -n "|"
repeat " " $spaces2
echo "|"
sequence=$(echo $(seq 0 $disks1 | tac))
for disk in $sequence; do
for rod in {1..3}; do
eval empty=$(( $DISKS - (Rod${rod}[$disk] / 2) ))
eval fill=\${Rod${rod}[$disk]}
repeat " " $empty
test $fill -gt 0 && repeat "*" $fill || echo -n "|"
repeat " " $empty
done
echo
done
repeat "=" $basewidth # Print "base" beneath rods.
echo
}
display ()
{
echo
PrintRods
# Get rod-number, summit and weight
first=( `FromRod $1` )
eval Rod${first[0]}[${first[1]}]=0
# Get rod-number and first-free position
second=( `ToRod ${first[2]} $2` )
eval Rod${second[0]}[${second[1]}]=${first[2]}
if [ "${Rod3[lastmove_t]}" = 1 ]
then # Last move? If yes, then display final position.
tput cup 0 0
echo; echo "+ Final Position: $Moves moves"
PrintRods
fi
sleep $DELAY
}
# From here down, almost the same as original (hanoi.bash) script.
dohanoi() { # Recursive function.
case $1 in
0)
;;
*)
dohanoi "$(($1-1))" $2 $4 $3
if [ "$Moves" -ne 0 ]
then
tput cup 0 0
echo; echo "+ Position after move $Moves"
fi
((Moves++))
echo -n " Next move will be: "
echo $2 "--&gt;" $3
display $2 $3
dohanoi "$(($1-1))" $4 $3 $2
;;
esac
}
setup_arrays ()
{
local dim n elem
let "dim1 = $1 - 1"
elem=$dim1
for n in $(seq 0 $dim1)
do
let "Rod1[$elem] = 2 * $n + 1"
Rod2[$n]=0
Rod3[$n]=0
((elem--))
done
}
### Main ###
trap "tput cnorm" 0
tput civis
clear
setup_arrays $DISKS
tput cup 0 0
echo; echo "+ Start Position"
case $# in
1) case $(($1&gt;0)) in # Must have at least one disk.
1)
disks=$1
dohanoi $1 1 3 2
# Total moves = 2^n - 1, where n = # of disks.
echo
exit 0;
;;
*)
echo "$0: Illegal value for number of disks";
exit $E_BADPARAM;
;;
esac
;;
*)
echo "usage: $0 N"
echo " Where \"N\" is the number of disks."
exit $E_NOPARAM;
;;
esac
exit $E_NOEXIT # Shouldn't exit here.
# Exercise:
# --------
# There is a minor bug in the script that causes the display of
#+ the next-to-last move to be skipped.
#+ Fix this.
#!/bin/bash
# UseGetOpt.sh
# Author: Peggy Russell <prusselltechgroup@gmail.com&gt;
UseGetOpt () {
declare inputOptions
declare -r E_OPTERR=85
declare -r ScriptName=${0##*/}
declare -r ShortOpts="adf:hlt"
declare -r LongOpts="aoption,debug,file:,help,log,test"
DoSomething () {
echo "The function name is '${FUNCNAME}'"
# Recall that $FUNCNAME is an internal variable
#+ holding the name of the function it is in.
}
inputOptions=$(getopt -o "${ShortOpts}" --long \
"${LongOpts}" --name "${ScriptName}" -- "${@}")
if [[ ($? -ne 0) || ($# -eq 0) ]]; then
echo "Usage: ${ScriptName} [-dhlt] {OPTION...}"
exit $E_OPTERR
fi
eval set -- "${inputOptions}"
# Only for educational purposes. Can be removed.
#-----------------------------------------------
echo "++ Test: Number of arguments: [$#]"
echo '++ Test: Looping through "$@"'
for a in "$@"; do
echo " ++ [$a]"
done
#-----------------------------------------------
while true; do
case "${1}" in
--aoption | -a) # Argument found.
echo "Option [$1]"
;;
--debug | -d) # Enable informational messages.
echo "Option [$1] Debugging enabled"
;;
--file | -f) # Check for optional argument.
case "$2" in #+ Double colon is optional argument.
"") # Not there.
echo "Option [$1] Use default"
shift
;;
*) # Got it
echo "Option [$1] Using input [$2]"
shift
;;
esac
DoSomething
;;
--log | -l) # Enable Logging.
echo "Option [$1] Logging enabled"
;;
--test | -t) # Enable testing.
echo "Option [$1] Testing enabled"
;;
--help | -h)
echo "Option [$1] Display help"
break
;;
--) # Done! $# is argument number for "--", $@ is "--"
echo "Option [$1] Dash Dash"
break
;;
*)
echo "Major internal error!"
exit 8
;;
esac
echo "Number of arguments: [$#]"
shift
done
shift
# Only for educational purposes. Can be removed.
#----------------------------------------------------------------------
echo "++ Test: Number of arguments after \"--\" is [$#] They are: [$@]"
echo '++ Test: Looping through "$@"'
for a in "$@"; do
echo " ++ [$a]"
done
#----------------------------------------------------------------------
}
################################### M A I N ########################
# If you remove "function UseGetOpt () {" and corresponding "}",
#+ you can uncomment the "exit 0" line below, and invoke this script
#+ with the various options from the command-line.
#-------------------------------------------------------------------
# exit 0
echo "Test 1"
UseGetOpt -f myfile one "two three" four
echo;echo "Test 2"
UseGetOpt -h
echo;echo "Test 3 - Short Options"
UseGetOpt -adltf myfile anotherfile
echo;echo "Test 4 - Long Options"
UseGetOpt --aoption --debug --log --test --file myfile anotherfile
exit
#!/bin/bash
# UseGetOpt-2.sh
# Modified version of the script for illustrating tab-expansion
#+ of command-line options.
# See the "Introduction to Tab Expansion" appendix.
# Possible options: -a -d -f -l -t -h
#+ --aoption, --debug --file --log --test -- help --
# Author of original script: Peggy Russell <prusselltechgroup@gmail.com&gt;
# UseGetOpt () {
declare inputOptions
declare -r E_OPTERR=85
declare -r ScriptName=${0##*/}
declare -r ShortOpts="adf:hlt"
declare -r LongOpts="aoption,debug,file:,help,log,test"
DoSomething () {
echo "The function name is '${FUNCNAME}'"
}
inputOptions=$(getopt -o "${ShortOpts}" --long \
"${LongOpts}" --name "${ScriptName}" -- "${@}")
if [[ ($? -ne 0) || ($# -eq 0) ]]; then
echo "Usage: ${ScriptName} [-dhlt] {OPTION...}"
exit $E_OPTERR
fi
eval set -- "${inputOptions}"
while true; do
case "${1}" in
--aoption | -a) # Argument found.
echo "Option [$1]"
;;
--debug | -d) # Enable informational messages.
echo "Option [$1] Debugging enabled"
;;
--file | -f) # Check for optional argument.
case "$2" in #+ Double colon is optional argument.
"") # Not there.
echo "Option [$1] Use default"
shift
;;
*) # Got it
echo "Option [$1] Using input [$2]"
shift
;;
esac
DoSomething
;;
--log | -l) # Enable Logging.
echo "Option [$1] Logging enabled"
;;
--test | -t) # Enable testing.
echo "Option [$1] Testing enabled"
;;
--help | -h)
echo "Option [$1] Display help"
break
;;
--) # Done! $# is argument number for "--", $@ is "--"
echo "Option [$1] Dash Dash"
break
;;
*)
echo "Major internal error!"
exit 8
;;
esac
echo "Number of arguments: [$#]"
shift
done
shift
# }
exit
#!/bin/bash
# show-all-colors.sh
# Displays all 256 possible background colors, using ANSI escape sequences.
# Author: Chetankumar Phulpagare
# Used in ABS Guide with permission.
T1=8
T2=6
T3=36
offset=0
for num1 in {0..7}
do {
for num2 in {0,1}
do {
shownum=`echo "$offset + $T1 * ${num2} + $num1" | bc`
echo -en "\E[0;48;5;${shownum}m color ${shownum} \E[0m"
}
done
echo
}
done
offset=16
for num1 in {0..5}
do {
for num2 in {0..5}
do {
for num3 in {0..5}
do {
shownum=`echo "$offset + $T2 * ${num3} \
+ $num2 + $T3 * ${num1}" | bc`
echo -en "\E[0;48;5;${shownum}m color ${shownum} \E[0m"
}
done
echo
}
done
}
done
offset=232
for num1 in {0..23}
do {
shownum=`expr $offset + $num1`
echo -en "\E[0;48;5;${shownum}m ${shownum}\E[0m"
}
done
echo
#!/bin/bash
# sam.sh, v. .01a
# Still Another Morse (code training script)
# With profuse apologies to Sam (F.B.) Morse.
# Author: Mendel Cooper
# License: GPL3
# Reldate: 05/25/11
# Morse code training script.
# Converts arguments to audible dots and dashes.
# Note: lowercase input only at this time.
# Get the wav files from the source tarball:
# http://bash.deta.in/abs-guide-latest.tar.bz2
DOT='soundfiles/dot.wav'
DASH='soundfiles/dash.wav'
# Maybe move soundfiles to /usr/local/sounds?
LETTERSPACE=300000 # Microseconds.
WORDSPACE=980000
# Nice and slow, for beginners. Maybe 5 wpm?
EXIT_MSG="May the Morse be with you!"
E_NOARGS=75 # No command-line args?
declare -A morse # Associative array!
# ======================================= #
morse[a]="dot; dash"
morse[b]="dash; dot; dot; dot"
morse[c]="dash; dot; dash; dot"
morse[d]="dash; dot; dot"
morse[e]="dot"
morse[f]="dot; dot; dash; dot"
morse[g]="dash; dash; dot"
morse[h]="dot; dot; dot; dot"
morse[i]="dot; dot;"
morse[j]="dot; dash; dash; dash"
morse[k]="dash; dot; dash"
morse[l]="dot; dash; dot; dot"
morse[m]="dash; dash"
morse[n]="dash; dot"
morse[o]="dash; dash; dash"
morse[p]="dot; dash; dash; dot"
morse[q]="dash; dash; dot; dash"
morse[r]="dot; dash; dot"
morse[s]="dot; dot; dot"
morse[t]="dash"
morse[u]="dot; dot; dash"
morse[v]="dot; dot; dot; dash"
morse[w]="dot; dash; dash"
morse[x]="dash; dot; dot; dash"
morse[y]="dash; dot; dash; dash"
morse[z]="dash; dash; dot; dot"
morse[0]="dash; dash; dash; dash; dash"
morse[1]="dot; dash; dash; dash; dash"
morse[2]="dot; dot; dash; dash; dash"
morse[3]="dot; dot; dot; dash; dash"
morse[4]="dot; dot; dot; dot; dash"
morse[5]="dot; dot; dot; dot; dot"
morse[6]="dash; dot; dot; dot; dot"
morse[7]="dash; dash; dot; dot; dot"
morse[8]="dash; dash; dash; dot; dot"
morse[9]="dash; dash; dash; dash; dot"
# The following must be escaped or quoted.
morse[?]="dot; dot; dash; dash; dot; dot"
morse[.]="dot; dash; dot; dash; dot; dash"
morse[,]="dash; dash; dot; dot; dash; dash"
morse[/]="dash; dot; dot; dash; dot"
morse[\@]="dot; dash; dash; dot; dash; dot"
# ======================================= #
play_letter ()
{
eval ${morse[$1]} # Play dots, dashes from appropriate sound files.
# Why is 'eval' necessary here?
usleep $LETTERSPACE # Pause in between letters.
}
extract_letters ()
{ # Slice string apart, letter by letter.
local pos=0 # Starting at left end of string.
local len=1 # One letter at a time.
strlen=${#1}
while [ $pos -lt $strlen ]
do
letter=${1:pos:len}
# ^^^^^^^^^^^^ See Chapter 10.1.
play_letter $letter
echo -n "*" # Mark letter just played.
((pos++))
done
}
######### Play the sounds ############
dot() { aplay "$DOT" 2&&gt;/dev/null; }
dash() { aplay "$DASH" 2&&gt;/dev/null; }
######################################
no_args ()
{
declare -a usage
usage=( $0 word1 word2 ... )
echo "Usage:"; echo
echo ${usage[*]}
for index in 0 1 2 3
do
extract_letters ${usage[index]}
usleep $WORDSPACE
echo -n " " # Print space between words.
done
# echo "Usage: $0 word1 word2 ... "
echo; echo
}
# int main()
# {
clear # Clear the terminal screen.
echo " SAM"
echo "Still Another Morse code trainer"
echo " Author: Mendel Cooper"
echo; echo;
if [ -z "$1" ]
then
no_args
echo; echo; echo "$EXIT_MSG"; echo
exit $E_NOARGS
fi
echo; echo "$*" # Print text that will be played.
until [ -z "$1" ]
do
extract_letters $1
shift # On to next word.
usleep $WORDSPACE
echo -n " " # Print space between words.
done
echo; echo; echo "$EXIT_MSG"; echo
exit 0
# }
# Exercises:
# ---------
# 1) Have the script accept either lowercase or uppercase words
#+ as arguments. Hint: Use 'tr' . . .
# 2) Have the script optionally accept input from a text file.
#!/bin/bash
# base64.sh: Bash implementation of Base64 encoding and decoding.
#
# Copyright (c) 2011 vladz <vladz@devzero.fr&gt;
# Used in ABSG with permission (thanks!).
#
# Encode or decode original Base64 (and also Base64url)
#+ from STDIN to STDOUT.
#
# Usage:
#
# Encode
# $ ./base64.sh < binary-file &gt; binary-file.base64
# Decode
# $ ./base64.sh -d < binary-file.base64 &gt; binary-file
#
# Reference:
#
# [1] RFC4648 - "The Base16, Base32, and Base64 Data Encodings"
# http://tools.ietf.org/html/rfc4648#section-5
# The base64_charset[] array contains entire base64 charset,
# and additionally the character "=" ...
base64_charset=( {A..Z} {a..z} {0..9} + / = )
# Nice illustration of brace expansion.
# Uncomment the ### line below to use base64url encoding instead of
#+ original base64.
### base64_charset=( {A..Z} {a..z} {0..9} - _ = )
# Output text width when encoding
#+ (64 characters, just like openssl output).
text_width=64
function display_base64_char {
# Convert a 6-bit number (between 0 and 63) into its corresponding values
#+ in Base64, then display the result with the specified text width.
printf "${base64_charset[$1]}"; (( width++ ))
(( width % text_width == 0 )) && printf "\n"
}
function encode_base64 {
# Encode three 8-bit hexadecimal codes into four 6-bit numbers.
# We need two local int array variables:
# c8[]: to store the codes of the 8-bit characters to encode
# c6[]: to store the corresponding encoded values on 6-bit
declare -a -i c8 c6
# Convert hexadecimal to decimal.
c8=( $(printf "ibase=16; ${1:0:2}\n${1:2:2}\n${1:4:2}\n" | bc) )
# Let's play with bitwise operators
#+ (3x8-bit into 4x6-bits conversion).
(( c6[0] = c8[0] &gt;&gt; 2 ))
(( c6[1] = ((c8[0] & 3) << 4) | (c8[1] &gt;&gt; 4) ))
# The following operations depend on the c8 element number.
case ${#c8[*]} in
3) (( c6[2] = ((c8[1] & 15) << 2) | (c8[2] &gt;&gt; 6) ))
(( c6[3] = c8[2] & 63 )) ;;
2) (( c6[2] = (c8[1] & 15) << 2 ))
(( c6[3] = 64 )) ;;
1) (( c6[2] = c6[3] = 64 )) ;;
esac
for char in ${c6[@]}; do
display_base64_char ${char}
done
}
function decode_base64 {
# Decode four base64 characters into three hexadecimal ASCII characters.
# c8[]: to store the codes of the 8-bit characters
# c6[]: to store the corresponding Base64 values on 6-bit
declare -a -i c8 c6
# Find decimal value corresponding to the current base64 character.
for current_char in ${1:0:1} ${1:1:1} ${1:2:1} ${1:3:1}; do
[ "${current_char}" = "=" ] && break
position=0
while [ "${current_char}" != "${base64_charset[${position}]}" ]; do
(( position++ ))
done
c6=( ${c6[*]} ${position} )
done
# Let's play with bitwise operators
#+ (4x8-bit into 3x6-bits conversion).
(( c8[0] = (c6[0] << 2) | (c6[1] &gt;&gt; 4) ))
# The next operations depends on the c6 elements number.
case ${#c6[*]} in
3) (( c8[1] = ( (c6[1] & 15) << 4) | (c6[2] &gt;&gt; 2) ))
(( c8[2] = (c6[2] & 3) << 6 )); unset c8[2] ;;
4) (( c8[1] = ( (c6[1] & 15) << 4) | (c6[2] &gt;&gt; 2) ))
(( c8[2] = ( (c6[2] & 3) << 6) | c6[3] )) ;;
esac
for char in ${c8[*]}; do
printf "\x$(printf "%x" ${char})"
done
}
# main ()
if [ "$1" = "-d" ]; then # decode
# Reformat STDIN in pseudo 4x6-bit groups.
content=$(cat - | tr -d "\n" | sed -r "s/(.{4})/\1 /g")
for chars in ${content}; do decode_base64 ${chars}; done
else
# Make a hexdump of stdin and reformat in 3-byte groups.
content=$(cat - | xxd -ps -u | sed -r "s/(\w{6})/\1 /g" |
tr -d "\n")
for chars in ${content}; do encode_base64 ${chars}; done
echo
fi
#!/bin/bash
# Prepends a string at a specified line
#+ in files with names ending in "sample"
#+ in the current working directory.
# 000000000000000000000000000000000000
# This script overwrites files!
# Be careful running it in a directory
#+ where you have important files!!!
# 000000000000000000000000000000000000
# Create a couple of files to operate on ...
# 01sample
# 02sample
# ... etc.
# These files must not be empty, else the prepend will not work.
lineno=1 # Append at line 1 (prepend).
filespec="*sample" # Filename pattern to operate on.
string=$(whoami) # Will set your username as string to insert.
# It could just as easily be any other string.
for file in $filespec # Specify which files to alter.
do # ^^^^^^^^^
sed -i ""$lineno"i "$string"" $file
# ^^ -i option edits files in-place.
# ^ Insert (i) command.
echo ""$file" altered!"
done
echo "Warning: files possibly clobbered!"
exit 0
# Exercise:
# Add error checking to this script.
# It needs it badly.
#!/bin/bash
# gronsfeld.bash
# License: GPL3
# Reldate 06/23/11
# This is an implementation of the Gronsfeld Cipher.
# It's essentially a stripped-down variant of the
#+ polyalphabetic Vigenčre Tableau, but with only 10 alphabets.
# The classic Gronsfeld has a numeric sequence as the key word,
#+ but here we substitute a letter string, for ease of use.
# Allegedly, this cipher was invented by the eponymous Count Gronsfeld
#+ in the 17th Century. It was at one time considered to be unbreakable.
# Note that this is ###not### a secure cipher by modern standards.
# Global Variables #
Enc_suffix="29379" # Encrypted text output with this 5-digit suffix.
# This functions as a decryption flag,
#+ and when used to generate passwords adds security.
Default_key="gronsfeldk"
# The script uses this if key not entered below
# (at "Keychain").
# Change the above two values frequently
#+ for added security.
GROUPLEN=5 # Output in groups of 5 letters, per tradition.
alpha1=( abcdefghijklmnopqrstuvwxyz )
alpha2=( {A..Z} ) # Output in all caps, per tradition.
# Use alpha2=( {a..z} ) for password generator.
wraplen=26 # Wrap around if past end of alphabet.
dflag= # Decrypt flag (set if $Enc_suffix present).
E_NOARGS=76 # Missing command-line args?
DEBUG=77 # Debugging flag.
declare -a offsets # This array holds the numeric shift values for
#+ encryption/decryption.
########Keychain#########
key= ### Put key here!!!
# 10 characters!
#########################
# Function
: ()
{ # Encrypt or decrypt, depending on whether $dflag is set.
# Why ": ()" as a function name? Just to prove that it can be done.
local idx keydx mlen off1 shft
local plaintext="$1"
local mlen=${#plaintext}
for (( idx=0; idx<$mlen; idx++ ))
do
let "keydx = $idx % $keylen"
shft=${offsets[keydx]}
if [ -n "$dflag" ]
then # Decrypt!
let "off1 = $(expr index "${alpha1[*]}" ${plaintext:idx:1}) - $shft"
# Shift backward to decrypt.
else # Encrypt!
let "off1 = $(expr index "${alpha1[*]}" ${plaintext:idx:1}) + $shft"
# Shift forward to encrypt.
test $(( $idx % $GROUPLEN)) = 0 && echo -n " " # Groups of 5 letters.
# Comment out above line for output as a string without whitespace,
#+ for example, if using the script as a password generator.
fi
((off1--)) # Normalize. Why is this necessary?
if [ $off1 -lt 0 ]
then # Catch negative indices.
let "off1 += $wraplen"
fi
((off1 %= $wraplen)) # Wrap around if past end of alphabet.
echo -n "${alpha2[off1]}"
done
if [ -z "$dflag" ]
then
echo " $Enc_suffix"
# echo "$Enc_suffix" # For password generator.
else
echo
fi
} # End encrypt/decrypt function.
# int main () {
# Check for command-line args.
if [ -z "$1" ]
then
echo "Usage: $0 TEXT TO ENCODE/DECODE"
exit $E_NOARGS
fi
if [ ${!#} == "$Enc_suffix" ]
# ^^^^^ Final command-line arg.
then
dflag=ON
echo -n "+" # Flag decrypted text with a "+" for easy ID.
fi
if [ -z "$key" ]
then
key="$Default_key" # "gronsfeldk" per above.
fi
keylen=${#key}
for (( idx=0; idx<$keylen; idx++ ))
do # Calculate shift values for encryption/decryption.
offsets[idx]=$(expr index "${alpha1[*]}" ${key:idx:1}) # Normalize.
((offsets[idx]--)) # Necessary because "expr index" starts at 1,
#+ whereas array count starts at 0.
# Generate array of numerical offsets corresponding to the key.
# There are simpler ways to accomplish this.
done
args=$(echo "$*" | sed -e 's/ //g' | tr A-Z a-z | sed -e 's/[0-9]//g')
# Remove whitespace and digits from command-line args.
# Can modify to also remove punctuation characters, if desired.
# Debug:
# echo "$args"; exit $DEBUG
: "$args" # Call the function named ":".
# : is a null operator, except . . . when it's a function name!
exit $? # } End-of-script
# ************************************************************** #
# This script can function as a password generator,
#+ with several minor mods, see above.
# That would allow an easy-to-remember password, even the word
#+ "password" itself, which encrypts to vrgfotvo29379
#+ a fairly secure password not susceptible to a dictionary attack.
# Or, you could use your own name (surely that's easy to remember!).
# For example, Bozo Bozeman encrypts to hfnbttdppkt29379.
# ************************************************************** #
#!/bin/bash
# bingo.sh
# Bingo number generator
# Reldate 20Aug12, License: Public Domain
#######################################################################
# This script generates bingo numbers.
# Hitting a key generates a new number.
# Hitting 'q' terminates the script.
# In a given run of the script, there will be no duplicate numbers.
# When the script terminates, it prints a log of the numbers generated.
#######################################################################
MIN=1 # Lowest allowable bingo number.
MAX=75 # Highest allowable bingo number.
COLS=15 # Numbers in each column (B I N G O).
SINGLE_DIGIT_MAX=9
declare -a Numbers
Prefix=(B I N G O)
initialize_Numbers ()
{ # Zero them out to start.
# They'll be incremented if chosen.
local index=0
until [ "$index" -gt $MAX ]
do
Numbers[index]=0
((index++))
done
Numbers[0]=1 # Flag zero, so it won't be selected.
}
generate_number ()
{
local number
while [ 1 ]
do
let "number = $(expr $RANDOM % $MAX)"
if [ ${Numbers[number]} -eq 0 ] # Number not yet called.
then
let "Numbers[number]+=1" # Flag it in the array.
break # And terminate loop.
fi # Else if already called, loop and generate another number.
done
# Exercise: Rewrite this more elegantly as an until-loop.
return $number
}
print_numbers_called ()
{ # Print out the called number log in neat columns.
# echo ${Numbers[@]}
local pre2=0 # Prefix a zero, so columns will align
#+ on single-digit numbers.
echo "Number Stats"
for (( index=1; index<=MAX; index++))
do
count=${Numbers[index]}
let "t = $index - 1" # Normalize, since array begins with index 0.
let "column = $(expr $t / $COLS)"
pre=${Prefix[column]}
# echo -n "${Prefix[column]} "
if [ $(expr $t % $COLS) -eq 0 ]
then
echo # Newline at end of row.
fi
if [ "$index" -gt $SINGLE_DIGIT_MAX ] # Check for single-digit number.
then
echo -n "$pre$index#$count "
else # Prefix a zero.
echo -n "$pre$pre2$index#$count "
fi
done
}
# main () {
RANDOM=$$ # Seed random number generator.
initialize_Numbers # Zero out the number tracking array.
clear
echo "Bingo Number Caller"; echo
while [[ "$key" != "q" ]] # Main loop.
do
read -s -n1 -p "Hit a key for the next number [q to exit] " key
# Usually 'q' exits, but not always.
# Can always hit Ctl-C if q fails.
echo
generate_number; new_number=$?
let "column = $(expr $new_number / $COLS)"
echo -n "${Prefix[column]} " # B-I-N-G-O
echo $new_number
done
echo; echo
# Game over ...
print_numbers_called
echo; echo "[#0 = not called . . . #1 = called]"
echo
exit 0
# }
# Certainly, this script could stand some improvement.
#See also the author's Instructable:
#www.instructables.com/id/Binguino-An-Arduino-based-Bingo-Number-Generato/
#!/bin/bash
# basics-reviewed.bash
# File extension == *.bash == specific to Bash
# Copyright (c) Michael S. Zick, 2003; All rights reserved.
# License: Use in any form, for any purpose.
# Revision: $ID$
#
# Edited for layout by M.C.
# (author of the "Advanced Bash Scripting Guide")
# Fixes and updates (04/08) by Cliff Bamford.
# This script tested under Bash versions 2.04, 2.05a and 2.05b.
# It may not work with earlier versions.
# This demonstration script generates one --intentional--
#+ "command not found" error message. See line 436.
# The current Bash maintainer, Chet Ramey, has fixed the items noted
#+ for later versions of Bash.
###-------------------------------------------###
### Pipe the output of this script to 'more' ###
###+ else it will scroll off the page. ###
### ###
### You may also redirect its output ###
###+ to a file for examination. ###
###-------------------------------------------###
# Most of the following points are described at length in
#+ the text of the foregoing "Advanced Bash Scripting Guide."
# This demonstration script is mostly just a reorganized presentation.
# -- msz
# Variables are not typed unless otherwise specified.
# Variables are named. Names must contain a non-digit.
# File descriptor names (as in, for example: 2&gt;&1)
#+ contain ONLY digits.
# Parameters and Bash array elements are numbered.
# (Parameters are very similar to Bash arrays.)
# A variable name may be undefined (null reference).
unset VarNull
# A variable name may be defined but empty (null contents).
VarEmpty='' # Two, adjacent, single quotes.
# A variable name may be defined and non-empty.
VarSomething='Literal'
# A variable may contain:
# * A whole number as a signed 32-bit (or larger) integer
# * A string
# A variable may also be an array.
# A string may contain embedded blanks and may be treated
#+ as if it where a function name with optional arguments.
# The names of variables and the names of functions
#+ are in different namespaces.
# A variable may be defined as a Bash array either explicitly or
#+ implicitly by the syntax of the assignment statement.
# Explicit:
declare -a ArrayVar
# The echo command is a builtin.
echo $VarSomething
# The printf command is a builtin.
# Translate %s as: String-Format
printf %s $VarSomething # No linebreak specified, none output.
echo # Default, only linebreak output.
# The Bash parser word breaks on whitespace.
# Whitespace, or the lack of it is significant.
# (This holds true in general; there are, of course, exceptions.)
# Translate the DOLLAR_SIGN character as: Content-Of.
# Extended-Syntax way of writing Content-Of:
echo ${VarSomething}
# The ${ ... } Extended-Syntax allows more than just the variable
#+ name to be specified.
# In general, $VarSomething can always be written as: ${VarSomething}.
# Call this script with arguments to see the following in action.
# Outside of double-quotes, the special characters @ and *
#+ specify identical behavior.
# May be pronounced as: All-Elements-Of.
# Without specification of a name, they refer to the
#+ pre-defined parameter Bash-Array.
# Glob-Pattern references
echo $* # All parameters to script or function
echo ${*} # Same
# Bash disables filename expansion for Glob-Patterns.
# Only character matching is active.
# All-Elements-Of references
echo $@ # Same as above
echo ${@} # Same as above
# Within double-quotes, the behavior of Glob-Pattern references
#+ depends on the setting of IFS (Input Field Separator).
# Within double-quotes, All-Elements-Of references behave the same.
# Specifying only the name of a variable holding a string refers
#+ to all elements (characters) of a string.
# To specify an element (character) of a string,
#+ the Extended-Syntax reference notation (see below) MAY be used.
# Specifying only the name of a Bash array references
#+ the subscript zero element,
#+ NOT the FIRST DEFINED nor the FIRST WITH CONTENTS element.
# Additional qualification is needed to reference other elements,
#+ which means that the reference MUST be written in Extended-Syntax.
# The general form is: ${name[subscript]}.
# The string forms may also be used: ${name:subscript}
#+ for Bash-Arrays when referencing the subscript zero element.
# Bash-Arrays are implemented internally as linked lists,
#+ not as a fixed area of storage as in some programming languages.
# Characteristics of Bash arrays (Bash-Arrays):
# --------------------------------------------
# If not otherwise specified, Bash-Array subscripts begin with
#+ subscript number zero. Literally: [0]
# This is called zero-based indexing.
###
# If not otherwise specified, Bash-Arrays are subscript packed
#+ (sequential subscripts without subscript gaps).
###
# Negative subscripts are not allowed.
###
# Elements of a Bash-Array need not all be of the same type.
###
# Elements of a Bash-Array may be undefined (null reference).
# That is, a Bash-Array may be "subscript sparse."
###
# Elements of a Bash-Array may be defined and empty (null contents).
###
# Elements of a Bash-Array may contain:
# * A whole number as a signed 32-bit (or larger) integer
# * A string
# * A string formated so that it appears to be a function name
# + with optional arguments
###
# Defined elements of a Bash-Array may be undefined (unset).
# That is, a subscript packed Bash-Array may be changed
# + into a subscript sparse Bash-Array.
###
# Elements may be added to a Bash-Array by defining an element
#+ not previously defined.
###
# For these reasons, I have been calling them "Bash-Arrays".
# I'll return to the generic term "array" from now on.
# -- msz
echo "========================================================="
# Lines 202 - 334 supplied by Cliff Bamford. (Thanks!)
# Demo --- Interaction with Arrays, quoting, IFS, echo, * and @ ---
#+ all affect how things work
ArrayVar[0]='zero' # 0 normal
ArrayVar[1]=one # 1 unquoted literal
ArrayVar[2]='two' # 2 normal
ArrayVar[3]='three' # 3 normal
ArrayVar[4]='I am four' # 4 normal with spaces
ArrayVar[5]='five' # 5 normal
unset ArrayVar[6] # 6 undefined
ArrayValue[7]='seven' # 7 normal
ArrayValue[8]='' # 8 defined but empty
ArrayValue[9]='nine' # 9 normal
echo '--- Here is the array we are using for this test'
echo
echo "ArrayVar[0]='zero' # 0 normal"
echo "ArrayVar[1]=one # 1 unquoted literal"
echo "ArrayVar[2]='two' # 2 normal"
echo "ArrayVar[3]='three' # 3 normal"
echo "ArrayVar[4]='I am four' # 4 normal with spaces"
echo "ArrayVar[5]='five' # 5 normal"
echo "unset ArrayVar[6] # 6 undefined"
echo "ArrayValue[7]='seven' # 7 normal"
echo "ArrayValue[8]='' # 8 defined but empty"
echo "ArrayValue[9]='nine' # 9 normal"
echo
echo
echo '---Case0: No double-quotes, Default IFS of space,tab,newline ---'
IFS=$'\x20'$'\x09'$'\x0A' # In exactly this order.
echo 'Here is: printf %q {${ArrayVar[*]}'
printf %q ${ArrayVar[*]}
echo
echo 'Here is: printf %q {${ArrayVar[@]}'
printf %q ${ArrayVar[@]}
echo
echo 'Here is: echo ${ArrayVar[*]}'
echo ${ArrayVar[@]}
echo 'Here is: echo {${ArrayVar[@]}'
echo ${ArrayVar[@]}
echo
echo '---Case1: Within double-quotes - Default IFS of space-tab-
newline ---'
IFS=$'\x20'$'\x09'$'\x0A' # These three bytes,
echo 'Here is: printf %q "{${ArrayVar[*]}"'
printf %q "${ArrayVar[*]}"
echo
echo 'Here is: printf %q "{${ArrayVar[@]}"'
printf %q "${ArrayVar[@]}"
echo
echo 'Here is: echo "${ArrayVar[*]}"'
echo "${ArrayVar[@]}"
echo 'Here is: echo "{${ArrayVar[@]}"'
echo "${ArrayVar[@]}"
echo
echo '---Case2: Within double-quotes - IFS is q'
IFS='q'
echo 'Here is: printf %q "{${ArrayVar[*]}"'
printf %q "${ArrayVar[*]}"
echo
echo 'Here is: printf %q "{${ArrayVar[@]}"'
printf %q "${ArrayVar[@]}"
echo
echo 'Here is: echo "${ArrayVar[*]}"'
echo "${ArrayVar[@]}"
echo 'Here is: echo "{${ArrayVar[@]}"'
echo "${ArrayVar[@]}"
echo
echo '---Case3: Within double-quotes - IFS is ^'
IFS='^'
echo 'Here is: printf %q "{${ArrayVar[*]}"'
printf %q "${ArrayVar[*]}"
echo
echo 'Here is: printf %q "{${ArrayVar[@]}"'
printf %q "${ArrayVar[@]}"
echo
echo 'Here is: echo "${ArrayVar[*]}"'
echo "${ArrayVar[@]}"
echo 'Here is: echo "{${ArrayVar[@]}"'
echo "${ArrayVar[@]}"
echo
echo '---Case4: Within double-quotes - IFS is ^ followed by
space,tab,newline'
IFS=$'^'$'\x20'$'\x09'$'\x0A' # ^ + space tab newline
echo 'Here is: printf %q "{${ArrayVar[*]}"'
printf %q "${ArrayVar[*]}"
echo
echo 'Here is: printf %q "{${ArrayVar[@]}"'
printf %q "${ArrayVar[@]}"
echo
echo 'Here is: echo "${ArrayVar[*]}"'
echo "${ArrayVar[@]}"
echo 'Here is: echo "{${ArrayVar[@]}"'
echo "${ArrayVar[@]}"
echo
echo '---Case6: Within double-quotes - IFS set and empty '
IFS=''
echo 'Here is: printf %q "{${ArrayVar[*]}"'
printf %q "${ArrayVar[*]}"
echo
echo 'Here is: printf %q "{${ArrayVar[@]}"'
printf %q "${ArrayVar[@]}"
echo
echo 'Here is: echo "${ArrayVar[*]}"'
echo "${ArrayVar[@]}"
echo 'Here is: echo "{${ArrayVar[@]}"'
echo "${ArrayVar[@]}"
echo
echo '---Case7: Within double-quotes - IFS is unset'
unset IFS
echo 'Here is: printf %q "{${ArrayVar[*]}"'
printf %q "${ArrayVar[*]}"
echo
echo 'Here is: printf %q "{${ArrayVar[@]}"'
printf %q "${ArrayVar[@]}"
echo
echo 'Here is: echo "${ArrayVar[*]}"'
echo "${ArrayVar[@]}"
echo 'Here is: echo "{${ArrayVar[@]}"'
echo "${ArrayVar[@]}"
echo
echo '---End of Cases---'
echo "========================================================="; echo
# Put IFS back to the default.
# Default is exactly these three bytes.
IFS=$'\x20'$'\x09'$'\x0A' # In exactly this order.
# Interpretation of the above outputs:
# A Glob-Pattern is I/O; the setting of IFS matters.
###
# An All-Elements-Of does not consider IFS settings.
###
# Note the different output using the echo command and the
#+ quoted format operator of the printf command.
# Recall:
# Parameters are similar to arrays and have the similar behaviors.
###
# The above examples demonstrate the possible variations.
# To retain the shape of a sparse array, additional script
#+ programming is required.
###
# The source code of Bash has a routine to output the
#+ [subscript]=value array assignment format.
# As of version 2.05b, that routine is not used,
#+ but that might change in future releases.
# The length of a string, measured in non-null elements (characters):
echo
echo '- - Non-quoted references - -'
echo 'Non-Null character count: '${#VarSomething}' characters.'
# test='Lit'$'\x00''eral' # $'\x00' is a null character.
# echo ${#test} # See that?
# The length of an array, measured in defined elements,
#+ including null content elements.
echo
echo 'Defined content count: '${#ArrayVar[@]}' elements.'
# That is NOT the maximum subscript (4).
# That is NOT the range of the subscripts (1 . . 4 inclusive).
# It IS the length of the linked list.
###
# Both the maximum subscript and the range of the subscripts may
#+ be found with additional script programming.
# The length of a string, measured in non-null elements (characters):
echo
echo '- - Quoted, Glob-Pattern references - -'
echo 'Non-Null character count: '"${#VarSomething}"' characters.'
# The length of an array, measured in defined elements,
#+ including null-content elements.
echo
echo 'Defined element count: '"${#ArrayVar[*]}"' elements.'
# Interpretation: Substitution does not effect the ${# ... } operation.
# Suggestion:
# Always use the All-Elements-Of character
#+ if that is what is intended (independence from IFS).
# Define a simple function.
# I include an underscore in the name
#+ to make it distinctive in the examples below.
###
# Bash separates variable names and function names
#+ in different namespaces.
# The Mark-One eyeball isn't that advanced.
###
_simple() {
echo -n 'SimpleFunc'$@ # Newlines are swallowed in
} #+ result returned in any case.
# The ( ... ) notation invokes a command or function.
# The $( ... ) notation is pronounced: Result-Of.
# Invoke the function _simple
echo
echo '- - Output of function _simple - -'
_simple # Try passing arguments.
echo
# or
(_simple) # Try passing arguments.
echo
echo '- Is there a variable of that name? -'
echo $_simple not defined # No variable by that name.
# Invoke the result of function _simple (Error msg intended)
###
$(_simple) # Gives an error message:
# line 436: SimpleFunc: command not found
# ---------------------------------------
echo
###
# The first word of the result of function _simple
#+ is neither a valid Bash command nor the name of a defined function.
###
# This demonstrates that the output of _simple is subject to evaluation.
###
# Interpretation:
# A function can be used to generate in-line Bash commands.
# A simple function where the first word of result IS a bash command:
###
_print() {
echo -n 'printf %q '$@
}
echo '- - Outputs of function _print - -'
_print parm1 parm2 # An Output NOT A Command.
echo
$(_print parm1 parm2) # Executes: printf %q parm1 parm2
# See above IFS examples for the
#+ various possibilities.
echo
$(_print $VarSomething) # The predictable result.
echo
# Function variables
# ------------------
echo
echo '- - Function variables - -'
# A variable may represent a signed integer, a string or an array.
# A string may be used like a function name with optional arguments.
# set -vx # Enable if desired
declare -f funcVar #+ in namespace of functions
funcVar=_print # Contains name of function.
$funcVar parm1 # Same as _print at this point.
echo
funcVar=$(_print ) # Contains result of function.
$funcVar # No input, No output.
$funcVar $VarSomething # The predictable result.
echo
funcVar=$(_print $VarSomething) # $VarSomething replaced HERE.
$funcVar # The expansion is part of the
echo #+ variable contents.
funcVar="$(_print $VarSomething)" # $VarSomething replaced HERE.
$funcVar # The expansion is part of the
echo #+ variable contents.
# The difference between the unquoted and the double-quoted versions
#+ above can be seen in the "protect_literal.sh" example.
# The first case above is processed as two, unquoted, Bash-Words.
# The second case above is processed as one, quoted, Bash-Word.
# Delayed replacement
# -------------------
echo
echo '- - Delayed replacement - -'
funcVar="$(_print '$VarSomething')" # No replacement, single Bash-Word.
eval $funcVar # $VarSomething replaced HERE.
echo
VarSomething='NewThing'
eval $funcVar # $VarSomething replaced HERE.
echo
# Restore the original setting trashed above.
VarSomething=Literal
# There are a pair of functions demonstrated in the
#+ "protect_literal.sh" and "unprotect_literal.sh" examples.
# These are general purpose functions for delayed replacement literals
#+ containing variables.
# REVIEW:
# ------
# A string can be considered a Classic-Array of elements (characters).
# A string operation applies to all elements (characters) of the string
#+ (in concept, anyway).
###
# The notation: ${array_name[@]} represents all elements of the
#+ Bash-Array: array_name.
###
# The Extended-Syntax string operations can be applied to all
#+ elements of an array.
###
# This may be thought of as a For-Each operation on a vector of strings.
###
# Parameters are similar to an array.
# The initialization of a parameter array for a script
#+ and a parameter array for a function only differ
#+ in the initialization of ${0}, which never changes its setting.
###
# Subscript zero of the script's parameter array contains
#+ the name of the script.
###
# Subscript zero of a function's parameter array DOES NOT contain
#+ the name of the function.
# The name of the current function is accessed by the $FUNCNAME variable.
###
# A quick, review list follows (quick, not short).
echo
echo '- - Test (but not change) - -'
echo '- null reference -'
echo -n ${VarNull-'NotSet'}' ' # NotSet
echo ${VarNull} # NewLine only
echo -n ${VarNull:-'NotSet'}' ' # NotSet
echo ${VarNull} # Newline only
echo '- null contents -'
echo -n ${VarEmpty-'Empty'}' ' # Only the space
echo ${VarEmpty} # Newline only
echo -n ${VarEmpty:-'Empty'}' ' # Empty
echo ${VarEmpty} # Newline only
echo '- contents -'
echo ${VarSomething-'Content'} # Literal
echo ${VarSomething:-'Content'} # Literal
echo '- Sparse Array -'
echo ${ArrayVar[@]-'not set'}
# ASCII-Art time
# State Y==yes, N==no
# - :-
# Unset Y Y ${# ... } == 0
# Empty N Y ${# ... } == 0
# Contents N N ${# ... } &gt; 0
# Either the first and/or the second part of the tests
#+ may be a command or a function invocation string.
echo
echo '- - Test 1 for undefined - -'
declare -i t
_decT() {
t=$t-1
}
# Null reference, set: t == -1
t=${#VarNull} # Results in zero.
${VarNull- _decT } # Function executes, t now -1.
echo $t
# Null contents, set: t == 0
t=${#VarEmpty} # Results in zero.
${VarEmpty- _decT } # _decT function NOT executed.
echo $t
# Contents, set: t == number of non-null characters
VarSomething='_simple' # Set to valid function name.
t=${#VarSomething} # non-zero length
${VarSomething- _decT } # Function _simple executed.
echo $t # Note the Append-To action.
# Exercise: clean up that example.
unset t
unset _decT
VarSomething=Literal
echo
echo '- - Test and Change - -'
echo '- Assignment if null reference -'
echo -n ${VarNull='NotSet'}' ' # NotSet NotSet
echo ${VarNull}
unset VarNull
echo '- Assignment if null reference -'
echo -n ${VarNull:='NotSet'}' ' # NotSet NotSet
echo ${VarNull}
unset VarNull
echo '- No assignment if null contents -'
echo -n ${VarEmpty='Empty'}' ' # Space only
echo ${VarEmpty}
VarEmpty=''
echo '- Assignment if null contents -'
echo -n ${VarEmpty:='Empty'}' ' # Empty Empty
echo ${VarEmpty}
VarEmpty=''
echo '- No change if already has contents -'
echo ${VarSomething='Content'} # Literal
echo ${VarSomething:='Content'} # Literal
# "Subscript sparse" Bash-Arrays
###
# Bash-Arrays are subscript packed, beginning with
#+ subscript zero unless otherwise specified.
###
# The initialization of ArrayVar was one way
#+ to "otherwise specify". Here is the other way:
###
echo
declare -a ArraySparse
ArraySparse=( [1]=one [2]='' [4]='four' )
# [0]=null reference, [2]=null content, [3]=null reference
echo '- - Array-Sparse List - -'
# Within double-quotes, default IFS, Glob-Pattern
IFS=$'\x20'$'\x09'$'\x0A'
printf %q "${ArraySparse[*]}"
echo
# Note that the output does not distinguish between "null content"
#+ and "null reference".
# Both print as escaped whitespace.
###
# Note also that the output does NOT contain escaped whitespace
#+ for the "null reference(s)" prior to the first defined element.
###
# This behavior of 2.04, 2.05a and 2.05b has been reported
#+ and may change in a future version of Bash.
# To output a sparse array and maintain the [subscript]=value
#+ relationship without change requires a bit of programming.
# One possible code fragment:
###
# local l=${#ArraySparse[@]} # Count of defined elements
# local f=0 # Count of found subscripts
# local i=0 # Subscript to test
( # Anonymous in-line function
for (( l=${#ArraySparse[@]}, f = 0, i = 0 ; f < l ; i++ ))
do
# 'if defined then...'
${ArraySparse[$i]+ eval echo '\ ['$i']='${ArraySparse[$i]} ; (( f++ )) }
done
)
# The reader coming upon the above code fragment cold
#+ might want to review "command lists" and "multiple commands on a line"
#+ in the text of the foregoing "Advanced Bash Scripting Guide."
###
# Note:
# The "read -a array_name" version of the "read" command
#+ begins filling array_name at subscript zero.
# ArraySparse does not define a value at subscript zero.
###
# The user needing to read/write a sparse array to either
#+ external storage or a communications socket must invent
#+ a read/write code pair suitable for their purpose.
###
# Exercise: clean it up.
unset ArraySparse
echo
echo '- - Conditional alternate (But not change)- -'
echo '- No alternate if null reference -'
echo -n ${VarNull+'NotSet'}' '
echo ${VarNull}
unset VarNull
echo '- No alternate if null reference -'
echo -n ${VarNull:+'NotSet'}' '
echo ${VarNull}
unset VarNull
echo '- Alternate if null contents -'
echo -n ${VarEmpty+'Empty'}' ' # Empty
echo ${VarEmpty}
VarEmpty=''
echo '- No alternate if null contents -'
echo -n ${VarEmpty:+'Empty'}' ' # Space only
echo ${VarEmpty}
VarEmpty=''
echo '- Alternate if already has contents -'
# Alternate literal
echo -n ${VarSomething+'Content'}' ' # Content Literal
echo ${VarSomething}
# Invoke function
echo -n ${VarSomething:+ $(_simple) }' ' # SimpleFunc Literal
echo ${VarSomething}
echo
echo '- - Sparse Array - -'
echo ${ArrayVar[@]+'Empty'} # An array of 'Empty'(ies)
echo
echo '- - Test 2 for undefined - -'
declare -i t
_incT() {
t=$t+1
}
# Note:
# This is the same test used in the sparse array
#+ listing code fragment.
# Null reference, set: t == -1
t=${#VarNull}-1 # Results in minus-one.
${VarNull+ _incT } # Does not execute.
echo $t' Null reference'
# Null contents, set: t == 0
t=${#VarEmpty}-1 # Results in minus-one.
${VarEmpty+ _incT } # Executes.
echo $t' Null content'
# Contents, set: t == (number of non-null characters)
t=${#VarSomething}-1 # non-null length minus-one
${VarSomething+ _incT } # Executes.
echo $t' Contents'
# Exercise: clean up that example.
unset t
unset _incT
# ${name?err_msg} ${name:?err_msg}
# These follow the same rules but always exit afterwards
#+ if an action is specified following the question mark.
# The action following the question mark may be a literal
#+ or a function result.
###
# ${name?} ${name:?} are test-only, the return can be tested.
# Element operations
# ------------------
echo
echo '- - Trailing sub-element selection - -'
# Strings, Arrays and Positional parameters
# Call this script with multiple arguments
#+ to see the parameter selections.
echo '- All -'
echo ${VarSomething:0} # all non-null characters
echo ${ArrayVar[@]:0} # all elements with content
echo ${@:0} # all parameters with content;
# ignoring parameter[0]
echo
echo '- All after -'
echo ${VarSomething:1} # all non-null after character[0]
echo ${ArrayVar[@]:1} # all after element[0] with content
echo ${@:2} # all after param[1] with content
echo
echo '- Range after -'
echo ${VarSomething:4:3} # ral
# Three characters after
# character[3]
echo '- Sparse array gotch -'
echo ${ArrayVar[@]:1:2} # four - The only element with content.
# Two elements after (if that many exist).
# the FIRST WITH CONTENTS
#+ (the FIRST WITH CONTENTS is being
#+ considered as if it
#+ were subscript zero).
# Executed as if Bash considers ONLY array elements with CONTENT
# printf %q "${ArrayVar[@]:0:3}" # Try this one
# In versions 2.04, 2.05a and 2.05b,
#+ Bash does not handle sparse arrays as expected using this notation.
#
# The current Bash maintainer, Chet Ramey, has corrected this.
echo '- Non-sparse array -'
echo ${@:2:2} # Two parameters following parameter[1]
# New victims for string vector examples:
stringZ=abcABC123ABCabc
arrayZ=( abcabc ABCABC 123123 ABCABC abcabc )
sparseZ=( [1]='abcabc' [3]='ABCABC' [4]='' [5]='123123' )
echo
echo ' - - Victim string - -'$stringZ'- - '
echo ' - - Victim array - -'${arrayZ[@]}'- - '
echo ' - - Sparse array - -'${sparseZ[@]}'- - '
echo ' - [0]==null ref, [2]==null ref, [4]==null content - '
echo ' - [1]=abcabc [3]=ABCABC [5]=123123 - '
echo ' - non-null-reference count: '${#sparseZ[@]}' elements'
echo
echo '- - Prefix sub-element removal - -'
echo '- - Glob-Pattern match must include the first character. - -'
echo '- - Glob-Pattern may be a literal or a function result. - -'
echo
# Function returning a simple, Literal, Glob-Pattern
_abc() {
echo -n 'abc'
}
echo '- Shortest prefix -'
echo ${stringZ#123} # Unchanged (not a prefix).
echo ${stringZ#$(_abc)} # ABC123ABCabc
echo ${arrayZ[@]#abc} # Applied to each element.
# echo ${sparseZ[@]#abc} # Version-2.05b core dumps.
# Has since been fixed by Chet Ramey.
# The -it would be nice- First-Subscript-Of
# echo ${#sparseZ[@]#*} # This is NOT valid Bash.
echo
echo '- Longest prefix -'
echo ${stringZ##1*3} # Unchanged (not a prefix)
echo ${stringZ##a*C} # abc
echo ${arrayZ[@]##a*c} # ABCABC 123123 ABCABC
# echo ${sparseZ[@]##a*c} # Version-2.05b core dumps.
# Has since been fixed by Chet Ramey.
echo
echo '- - Suffix sub-element removal - -'
echo '- - Glob-Pattern match must include the last character. - -'
echo '- - Glob-Pattern may be a literal or a function result. - -'
echo
echo '- Shortest suffix -'
echo ${stringZ%1*3} # Unchanged (not a suffix).
echo ${stringZ%$(_abc)} # abcABC123ABC
echo ${arrayZ[@]%abc} # Applied to each element.
# echo ${sparseZ[@]%abc} # Version-2.05b core dumps.
# Has since been fixed by Chet Ramey.
# The -it would be nice- Last-Subscript-Of
# echo ${#sparseZ[@]%*} # This is NOT valid Bash.
echo
echo '- Longest suffix -'
echo ${stringZ%%1*3} # Unchanged (not a suffix)
echo ${stringZ%%b*c} # a
echo ${arrayZ[@]%%b*c} # a ABCABC 123123 ABCABC a
# echo ${sparseZ[@]%%b*c} # Version-2.05b core dumps.
# Has since been fixed by Chet Ramey.
echo
echo '- - Sub-element replacement - -'
echo '- - Sub-element at any location in string. - -'
echo '- - First specification is a Glob-Pattern - -'
echo '- - Glob-Pattern may be a literal or Glob-Pattern function result. - -'
echo '- - Second specification may be a literal or function result. - -'
echo '- - Second specification may be unspecified. Pronounce that'
echo ' as: Replace-With-Nothing (Delete) - -'
echo
# Function returning a simple, Literal, Glob-Pattern
_123() {
echo -n '123'
}
echo '- Replace first occurrence -'
echo ${stringZ/$(_123)/999} # Changed (123 is a component).
echo ${stringZ/ABC/xyz} # xyzABC123ABCabc
echo ${arrayZ[@]/ABC/xyz} # Applied to each element.
echo ${sparseZ[@]/ABC/xyz} # Works as expected.
echo
echo '- Delete first occurrence -'
echo ${stringZ/$(_123)/}
echo ${stringZ/ABC/}
echo ${arrayZ[@]/ABC/}
echo ${sparseZ[@]/ABC/}
# The replacement need not be a literal,
#+ since the result of a function invocation is allowed.
# This is general to all forms of replacement.
echo
echo '- Replace first occurrence with Result-Of -'
echo ${stringZ/$(_123)/$(_simple)} # Works as expected.
echo ${arrayZ[@]/ca/$(_simple)} # Applied to each element.
echo ${sparseZ[@]/ca/$(_simple)} # Works as expected.
echo
echo '- Replace all occurrences -'
echo ${stringZ//[b2]/X} # X-out b's and 2's
echo ${stringZ//abc/xyz} # xyzABC123ABCxyz
echo ${arrayZ[@]//abc/xyz} # Applied to each element.
echo ${sparseZ[@]//abc/xyz} # Works as expected.
echo
echo '- Delete all occurrences -'
echo ${stringZ//[b2]/}
echo ${stringZ//abc/}
echo ${arrayZ[@]//abc/}
echo ${sparseZ[@]//abc/}
echo
echo '- - Prefix sub-element replacement - -'
echo '- - Match must include the first character. - -'
echo
echo '- Replace prefix occurrences -'
echo ${stringZ/#[b2]/X} # Unchanged (neither is a prefix).
echo ${stringZ/#$(_abc)/XYZ} # XYZABC123ABCabc
echo ${arrayZ[@]/#abc/XYZ} # Applied to each element.
echo ${sparseZ[@]/#abc/XYZ} # Works as expected.
echo
echo '- Delete prefix occurrences -'
echo ${stringZ/#[b2]/}
echo ${stringZ/#$(_abc)/}
echo ${arrayZ[@]/#abc/}
echo ${sparseZ[@]/#abc/}
echo
echo '- - Suffix sub-element replacement - -'
echo '- - Match must include the last character. - -'
echo
echo '- Replace suffix occurrences -'
echo ${stringZ/%[b2]/X} # Unchanged (neither is a suffix).
echo ${stringZ/%$(_abc)/XYZ} # abcABC123ABCXYZ
echo ${arrayZ[@]/%abc/XYZ} # Applied to each element.
echo ${sparseZ[@]/%abc/XYZ} # Works as expected.
echo
echo '- Delete suffix occurrences -'
echo ${stringZ/%[b2]/}
echo ${stringZ/%$(_abc)/}
echo ${arrayZ[@]/%abc/}
echo ${sparseZ[@]/%abc/}
echo
echo '- - Special cases of null Glob-Pattern - -'
echo
echo '- Prefix all -'
# null substring pattern means 'prefix'
echo ${stringZ/#/NEW} # NEWabcABC123ABCabc
echo ${arrayZ[@]/#/NEW} # Applied to each element.
echo ${sparseZ[@]/#/NEW} # Applied to null-content also.
# That seems reasonable.
echo
echo '- Suffix all -'
# null substring pattern means 'suffix'
echo ${stringZ/%/NEW} # abcABC123ABCabcNEW
echo ${arrayZ[@]/%/NEW} # Applied to each element.
echo ${sparseZ[@]/%/NEW} # Applied to null-content also.
# That seems reasonable.
echo
echo '- - Special case For-Each Glob-Pattern - -'
echo '- - - - This is a nice-to-have dream - - - -'
echo
_GenFunc() {
echo -n ${0} # Illustration only.
# Actually, that would be an arbitrary computation.
}
# All occurrences, matching the AnyThing pattern.
# Currently //*/ does not match null-content nor null-reference.
# /#/ and /%/ does match null-content but not null-reference.
echo ${sparseZ[@]//*/$(_GenFunc)}
# A possible syntax would be to make
#+ the parameter notation used within this construct mean:
# ${1} - The full element
# ${2} - The prefix, if any, to the matched sub-element
# ${3} - The matched sub-element
# ${4} - The suffix, if any, to the matched sub-element
#
# echo ${sparseZ[@]//*/$(_GenFunc ${3})} # Same as ${1} here.
# Perhaps it will be implemented in a future version of Bash.
exit 0
#!/bin/bash
# test-execution-time.sh
# Example by Erik Brandsberg, for testing execution time
#+ of certain operations.
# Referenced in the "Optimizations" section of "Miscellany" chapter.
count=50000
echo "Math tests"
echo "Math via \$(( ))"
time for (( i=0; i< $count; i++))
do
result=$(( $i%2 ))
done
echo "Math via *expr*:"
time for (( i=0; i< $count; i++))
do
result=`expr "$i%2"`
done
echo "Math via *let*:"
time for (( i=0; i< $count; i++))
do
let result=$i%2
done
echo
echo "Conditional testing tests"
echo "Test via case:"
time for (( i=0; i< $count; i++))
do
case $(( $i%2 )) in
0) : ;;
1) : ;;
esac
done
echo "Test with if [], no quotes:"
time for (( i=0; i< $count; i++))
do
if [ $(( $i%2 )) = 0 ]; then
:
else
:
fi
done
echo "Test with if [], quotes:"
time for (( i=0; i< $count; i++))
do
if [ "$(( $i%2 ))" = "0" ]; then
:
else
:
fi
done
echo "Test with if [], using -eq:"
time for (( i=0; i< $count; i++))
do
if [ $(( $i%2 )) -eq 0 ]; then
:
else
:
fi
done
exit $?
#!/bin/bash
# assoc-arr-test.sh
# Benchmark test script to compare execution times of
# numeric-indexed array vs. associative array.
# Thank you, Erik Brandsberg.
count=100000 # May take a while for some of the tests below.
declare simple # Can change to 20000, if desired.
declare -a array1
declare -A array2
declare -a array3
declare -A array4
echo "===Assignment tests==="
echo
echo "Assigning a simple variable:"
# References $i twice to equalize lookup times.
time for (( i=0; i< $count; i++)); do
simple=$i$i
done
echo "---"
echo "Assigning a numeric index array entry:"
time for (( i=0; i< $count; i++)); do
array1[$i]=$i
done
echo "---"
echo "Overwriting a numeric index array entry:"
time for (( i=0; i< $count; i++)); do
array1[$i]=$i
done
echo "---"
echo "Linear reading of numeric index array:"
time for (( i=0; i< $count; i++)); do
simple=array1[$i]
done
echo "---"
echo "Assigning an associative array entry:"
time for (( i=0; i< $count; i++)); do
array2[$i]=$i
done
echo "---"
echo "Overwriting an associative array entry:"
time for (( i=0; i< $count; i++)); do
array2[$i]=$i
done
echo "---"
echo "Linear reading an associative array entry:"
time for (( i=0; i< $count; i++)); do
simple=array2[$i]
done
echo "---"
echo "Assigning a random number to a simple variable:"
time for (( i=0; i< $count; i++)); do
simple=$RANDOM
done
echo "---"
echo "Assign a sparse numeric index array entry randomly into 64k cells:"
time for (( i=0; i< $count; i++)); do
array3[$RANDOM]=$i
done
echo "---"
echo "Reading sparse numeric index array entry:"
time for value in "${array3[@]}"i; do
simple=$value
done
echo "---"
echo "Assigning a sparse associative array entry randomly into 64k cells:"
time for (( i=0; i< $count; i++)); do
array4[$RANDOM]=$i
done
echo "---"
echo "Reading sparse associative index array entry:"
time for value in "${array4[@]}"; do
simple=$value
done
exit $?</pre>]
#!/bin/bash
ARGCOUNT=1 # Need name as argument.
E_WRONGARGS=65
if [ number-of-arguments is-not-equal-to "$ARGCOUNT" ]
# ^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^
# Can't figure out how to code this . . .
#+ . . . so write it in pseudo-code.
then
echo "Usage: name-of-script name"
# ^^^^^^^^^^^^^^ More pseudo-code.
exit $E_WRONGARGS
fi
. . .
exit 0
# Later on, substitute working code for the pseudo-code.
# Line 6 becomes:
if [ $# -ne "$ARGCOUNT" ]
# Line 12 becomes:
echo "Usage: `basename $0` name"
# Append (&gt;&gt;) following to end of each script tracked.
whoami&gt;&gt; $SAVE_FILE # User invoking the script.
echo $0&gt;&gt; $SAVE_FILE # Script name.
date&gt;&gt; $SAVE_FILE # Date and time.
echo&gt;&gt; $SAVE_FILE # Blank line as separator.
# Of course, SAVE_FILE defined and exported as environmental variable in ~/.bashrc
#+ (something like ~/.scripts-run)
file=data.txt
title="***This is the title line of data text file***"
echo $title | cat - $file &gt;$file.new
# "cat -" concatenates stdout to $file.
# End result is
#+ to write a new file with $title appended at *beginning*.
# SCRIPT LIBRARY
# ------ -------
# Note:
# No "#!" here.
# No "live code" either.
# Useful variable definitions
ROOT_UID=0 # Root has $UID 0.
E_NOTROOT=101 # Not root user error.
MAXRETVAL=255 # Maximum (positive) return value of a function.
SUCCESS=0
FAILURE=-1
# Functions
Usage () # "Usage:" message.
{
if [ -z "$1" ] # No arg passed.
then
msg=filename
else
msg=$@
fi
echo "Usage: `basename $0` "$msg""
}
Check_if_root () # Check if root running script.
{ # From "ex39.sh" example.
if [ "$UID" -ne "$ROOT_UID" ]
then
echo "Must be root to run this script."
exit $E_NOTROOT
fi
}
CreateTempfileName () # Creates a "unique" temp filename.
{ # From "ex51.sh" example.
prefix=temp
suffix=`eval date +%s`
Tempfilename=$prefix.$suffix
}
isalpha2 () # Tests whether *entire string* is alphabetic.
{ # From "isalpha.sh" example.
[ $# -eq 1 ] || return $FAILURE
case $1 in
*[!a-zA-Z]*|"") return $FAILURE;;
*) return $SUCCESS;;
esac # Thanks, S.C.
}
abs () # Absolute value.
{ # Caution: Max return value = 255.
E_ARGERR=-999999
if [ -z "$1" ] # Need arg passed.
then
return $E_ARGERR # Obvious error value returned.
fi
if [ "$1" -ge 0 ] # If non-negative,
then #
absval=$1 # stays as-is.
else # Otherwise,
let "absval = (( 0 - $1 ))" # change sign.
fi
return $absval
}
tolower () # Converts string(s) passed as argument(s)
{ #+ to lowercase.
if [ -z "$1" ] # If no argument(s) passed,
then #+ send error message
echo "(null)" #+ (C-style void-pointer error message)
return #+ and return from function.
fi
echo "$@" | tr A-Z a-z
# Translate all passed arguments ($@).
return
# Use command substitution to set a variable to function output.
# For example:
# oldvar="A seT of miXed-caSe LEtTerS"
# newvar=`tolower "$oldvar"`
# echo "$newvar" # a set of mixed-case letters
#
# Exercise: Rewrite this function to change lowercase passed argument(s)
# to uppercase ... toupper() [easy].
}
## Caution.
rm -rf *.zzy ## The "-rf" options to "rm" are very dangerous,
##+ especially with wild cards.
#+ Line continuation.
# This is line 1
#+ of a multi-line comment,
#+ and this is the final line.
#* Note.
#o List item.
#&gt; Another point of view.
while [ "$var1" != "end" ] #&gt; while test "$var1" != "end"
#!/bin/bash
# progress-bar.sh
# Author: Dotan Barak (very minor revisions by ABS Guide author).
# Used in ABS Guide with permission (thanks!).
BAR_WIDTH=50
BAR_CHAR_START="["
BAR_CHAR_END="]"
BAR_CHAR_EMPTY="."
BAR_CHAR_FULL="="
BRACKET_CHARS=2
LIMIT=100
print_progress_bar()
{
# Calculate how many characters will be full.
let "full_limit = ((($1 - $BRACKET_CHARS) * $2) / $LIMIT)"
# Calculate how many characters will be empty.
let "empty_limit = ($1 - $BRACKET_CHARS) - ${full_limit}"
# Prepare the bar.
bar_line="${BAR_CHAR_START}"
for ((j=0; j<full_limit; j++)); do
bar_line="${bar_line}${BAR_CHAR_FULL}"
done
for ((j=0; j<empty_limit; j++)); do
bar_line="${bar_line}${BAR_CHAR_EMPTY}"
done
bar_line="${bar_line}${BAR_CHAR_END}"
printf "%3d%% %s" $2 ${bar_line}
}
# Here is a sample of code that uses it.
MAX_PERCENT=100
for ((i=0; i<=MAX_PERCENT; i++)); do
#
usleep 10000
# ... Or run some other commands ...
#
print_progress_bar ${BAR_WIDTH} ${i}
echo -en "\r"
done
echo ""
exit
#!/bin/bash
COMMENT_BLOCK=
# Try setting the above variable to some value
#+ for an unpleasant surprise.
if [ $COMMENT_BLOCK ]; then
Comment block --
=================================
This is a comment line.
This is another comment line.
This is yet another comment line.
=================================
echo "This will not echo."
Comment blocks are error-free! Whee!
fi
echo "No more comments, please."
exit 0
#!/bin/bash
SUCCESS=0
E_BADINPUT=85
test "$1" -ne 0 -o "$1" -eq 0 2&gt;/dev/null
# An integer is either equal to 0 or not equal to 0.
# 2&gt;/dev/null suppresses error message.
if [ $? -ne "$SUCCESS" ]
then
echo "Usage: `basename $0` integer-input"
exit $E_BADINPUT
fi
let "sum = $1 + 25" # Would give error if $1 not integer.
echo "Sum = $sum"
# Any variable, not just a command-line parameter, can be tested this way.
exit 0
#!/bin/bash
# multiplication.sh
multiply () # Multiplies params passed.
{ # Will accept a variable number of args.
local product=1
until [ -z "$1" ] # Until uses up arguments passed...
do
let "product *= $1"
shift
done
echo $product # Will not echo to stdout,
} #+ since this will be assigned to a variable.
mult1=15383; mult2=25211
val1=`multiply $mult1 $mult2`
# Assigns stdout (echo) of function to the variable val1.
echo "$mult1 X $mult2 = $val1" # 387820813
mult1=25; mult2=5; mult3=20
val2=`multiply $mult1 $mult2 $mult3`
echo "$mult1 X $mult2 X $mult3 = $val2" # 2500
mult1=188; mult2=37; mult3=25; mult4=47
val3=`multiply $mult1 $mult2 $mult3 $mult4`
echo "$mult1 X $mult2 X $mult3 X $mult4 = $val3" # 8173300
exit 0
capitalize_ichar () # Capitalizes initial character
{ #+ of argument string(s) passed.
string0="$@" # Accepts multiple arguments.
firstchar=${string0:0:1} # First character.
string1=${string0:1} # Rest of string(s).
FirstChar=`echo "$firstchar" | tr a-z A-Z`
# Capitalize first character.
echo "$FirstChar$string1" # Output to stdout.
}
newstring=`capitalize_ichar "every sentence should start with a capital letter."`
echo "$newstring" # Every sentence should start with a capital letter.
#!/bin/bash
# sum-product.sh
# A function may "return" more than one value.
sum_and_product () # Calculates both sum and product of passed args.
{
echo $(( $1 + $2 )) $(( $1 * $2 ))
# Echoes to stdout each calculated value, separated by space.
}
echo
echo "Enter first number "
read first
echo
echo "Enter second number "
read second
echo
retval=`sum_and_product $first $second` # Assigns output of function.
sum=`echo "$retval" | awk '{print $1}'` # Assigns first field.
product=`echo "$retval" | awk '{print $2}'` # Assigns second field.
echo "$first + $second = $sum"
echo "$first * $second = $product"
echo
exit 0
sum_and_product ()
{
echo "This is the sum_and_product function." # This messes things up!
echo $(( $1 + $2 )) $(( $1 * $2 ))
}
...
retval=`sum_and_product $first $second` # Assigns output of function.
# Now, this will not work correctly.
#!/bin/bash
# array-function.sh: Passing an array to a function and ...
# "returning" an array from a function
Pass_Array ()
{
local passed_array # Local variable!
passed_array=( `echo "$1"` )
echo "${passed_array[@]}"
# List all the elements of the new array
#+ declared and set within the function.
}
original_array=( element1 element2 element3 element4 element5 )
echo
echo "original_array = ${original_array[@]}"
# List all elements of original array.
# This is the trick that permits passing an array to a function.
# **********************************
argument=`echo ${original_array[@]}`
# **********************************
# Pack a variable
#+ with all the space-separated elements of the original array.
#
# Attempting to just pass the array itself will not work.
# This is the trick that allows grabbing an array as a "return value".
# *****************************************
returned_array=( `Pass_Array "$argument"` )
# *****************************************
# Assign 'echoed' output of function to array variable.
echo "returned_array = ${returned_array[@]}"
echo "============================================================="
# Now, try it again,
#+ attempting to access (list) the array from outside the function.
Pass_Array "$argument"
# The function itself lists the array, but ...
#+ accessing the array from outside the function is forbidden.
echo "Passed array (within function) = ${passed_array[@]}"
# NULL VALUE since the array is a variable local to the function.
echo
############################################
# And here is an even more explicit example:
ret_array ()
{
for element in {11..20}
do
echo "$element " # Echo individual elements
done #+ of what will be assembled into an array.
}
arr=( $(ret_array) ) # Assemble into array.
echo "Capturing array \"arr\" from function ret_array () ..."
echo "Third element of array \"arr\" is ${arr[2]}." # 13 (zero-indexed)
echo -n "Entire array is: "
echo ${arr[@]} # 11 12 13 14 15 16 17 18 19 20
echo
exit 0
# Nathan Coulter points out that passing arrays with elements containing
#+ whitespace breaks this example.
#!/bin/bash
PATH=/bin:/usr/bin:/usr/local/bin ; export PATH
umask 022 # Files that the script creates will have 755 permission.
# Thanks to Ian D. Allen, for this tip.
# From "wstrings.sh" example.
wlist=`strings "$1" | tr A-Z a-z | tr '[:space:]' Z | \
tr -cs '[:alpha:]' Z | tr -s '\173-\377' Z | tr Z ' '`
#!/bin/bash
# agram.sh: Playing games with anagrams.
# Find anagrams of...
LETTERSET=etaoinshrdlu
FILTER='.......' # How many letters minimum?
# 1234567
anagram "$LETTERSET" | # Find all anagrams of the letterset...
grep "$FILTER" | # With at least 7 letters,
grep '^is' | # starting with 'is'
grep -v 's$' | # no plurals
grep -v 'ed$' # no past tense verbs
# Possible to add many combinations of conditions and filters.
# Uses "anagram" utility
#+ that is part of the author's "yawl" word list package.
# http://ibiblio.org/pub/Linux/libs/yawl-0.3.2.tar.gz
# http://bash.deta.in/yawl-0.3.2.tar.gz
exit 0 # End of code.
bash$ sh agram.sh
islander
isolate
isolead
isotheral
# Exercises:
# ---------
# Modify this script to take the LETTERSET as a command-line parameter.
# Parameterize the filters in lines 11 - 13 (as with $FILTER),
#+ so that they can be specified by passing arguments to a function.
# For a slightly different approach to anagramming,
#+ see the agram2.sh script.
CMD=command1 # First choice.
PlanB=command2 # Fallback option.
command_test=$(whatis "$CMD" | grep 'nothing appropriate')
# If 'command1' not found on system , 'whatis' will return
#+ "command1: nothing appropriate."
#
# A safer alternative is:
# command_test=$(whereis "$CMD" | grep \/)
# But then the sense of the following test would have to be reversed,
#+ since the $command_test variable holds content only if
#+ the $CMD exists on the system.
# (
@Meaticus22
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