Basic Shell Scripting

myscript.sh

#! /usr/bin/bash

# echo Hello World!!

# sleep 3

# VARIABLE
# uPPERCASE BY CONVENTIONS
# LETTERS NUMBERS UNDERSCORES

# NAME="Bob"
# echo "my name is $NAME"

# User Input
# read -p "Enter your name: " NAME
# echo "Hello $NAME, nice to meet you"

# If statement
# if [ "$NAME" == "Sam" ]
# then
# echo "Your name is Sam"
# fi

# If-Else statement
#  if [ "$NAME" == "Sam" ]
#  then
#     echo "Your name is Sam"
# else 
#     echo Searching....
# sleep 3
#     echo "Your name is not registered"
#  fi

# ELSE-IF Statement
# if [ "$NAME" == "Sam" ]
# then
#      echo Searching...
# sleep 3
#      echo "Your name is Sam"
#  elif [ "$NAME" == "Jack" ]
#  then
#      echo Searching...
# sleep 3 
#      echo "Your name is Jack"
#  else 
#      echo Searching....
#  sleep 3
#      echo "Your name is not registered"
#   fi

#COMPARISIONS
# NUM1=32
# NUM2=5
# if [ "$NUM1" -gt "$NUM2" ]
# then
#    echo "$NUM1 is greater than $NUM2"
# else
#    echo "$NUM1 is less than $NUM2"
# fi  

########
# val1 -eq (equal) val2 Returns true if the values are equal
# val1 -ne (not eq) val2 Returns true if the values are not equal
# val1 -gt (grt than) val2 Returns true if val1 is greater than val2
# val1 -ge (grt than or eq) val2 Returns true if val1 is greater than or equal to val2
# val1 -lt (less than) val2 Returns true if val1 is less than val2
# val1 -le (less than or eq) val2 Returns true if val1 is less than or equal to val2
########


#FILE CONDITIONS
# FILE="hello.txt"
# if [ -f "$FILE" ]
# then
#   echo Searching Directory....
#   sleep 2
#   echo "$FILE exists"
# else
#   echo Searching Directory....
#   sleep 2 
#   echo "$FILE does NOT exist"
# fi

########
# -d file   True if the file is a directory
# -e file   True if the file exists (note that this is not particularly portable, thus -f is generally used)
# -f file   True if the provided string is a file
# -g file   True if the group id is set on a file
# -r file   True if the file is readable
# -s file   True if the file has a non-zero size
# -u    True if the user id is set on a file
# -w    True if the file is writable
# -x    True if the file is an executable
########

#Case Statements

# read -p "Are you 21 or above? Y/N " ANSWER
# case "$ANSWER" in 
#     [y/Y] | [y/Y][e/E][s/S])
#       echo "Veryfing..."
#     sleep 2
#       echo "You can have a beer :)"
#       ;;
#     [n/N] | [n/N][o/O])
#       echo "Veryfing..."
#     sleep 2
#       echo "You can't have a beer :("
#       ;;
#     *) #incase user inputs anything other than required answer
#       echo "Please enter y/yes or n/no"
#    esac   


#  #Simple for loop
#  NAMES="Jack Sam Temi Mike"
# for NAME in $NAMES 
#   do 
#    echo  "Hello $NAME"
# done  

#FOR LOOP
# FILES=$(ls *.txt)
# NEW="new"

# for FILE in $FILES
#    do
#      echo "Renaming $FILE to new-$FILE"
#       mv $FILE $NEW-$FILE
# done       

#While loop Reading through lines

# LINE=1
# while read -r CURRENT_LINE
#   do
#     echo "$LINE: $CURRENT_LINE"
#     ((LINE++))
# done < "./new-1.txt"

# FUNCTION
# function sayHello() {
#   echo "Hello World"
# }
# sayHello

# FUNCTION WITH PARAMS
# function greet() {
#   echo "Hello, I am $1 and I am $2"
# }

# greet "Brad" "36"

# CREATE FOLDER AND WRITE TO A FILE
# mkdir hello
# touch "hello/world.txt"
# echo "Hello World" >> "hello/world.txt"
# echo "Created hello/world.txt"