Use bash , ncal , Perl to list years, months, and weeks with week numbers

gistfile1.txt

#! /usr/bin/env bash

#use ncal and perl to list weeks in a year range
#can also use cal in cygwin

#arg 1 year_start
#arg 2 year_end
#arg 3 mode "cal" # WIP

function showhelp() {
 echo "Usage:"
 echo "$0 help|h|-h <-- this message"
 echo "$0 <no parameter> <-- current month (current year implicit)"
 echo "$0 year1  <-- year and current month"
 echo "$0 year1 year2 <-- year span and current month"
 echo "$0 year1 year2 cal <-- mode for cygwin with cal"
 exit
}

argcount=$#

ystt=$1
yend=$2

currY=$(date +"%Y")


# # # Initial Logic Checks, Invariants
if [ $argcount -eq 0 ]; then
 ystt=$currY
 yend=$currY
 echo "mode 1 year $ystt"

elif [ $argcount -eq 1  ]; then
# echo "$@"
 args=("$@");
 arg1=${args[0]}
 re='^[0-9]+$'
 if ! [[ $arg1 =~ $re ]] ; then
  showhelp
 fi
fi



# # # Values have been established

if [[ $argcount -eq 2 && "$yend" -lt "$ystt" ]]; then
 echo "arg 2 ($yend) cannot be less than arg 1 ($ystt)"
 exit 

elif [[ "$OSTYPE" == "linux-gnu"* && $argcount -eq 3 ]]; then
 echo "Mode with 3 args is for cal in cygwin"
 exit
#ref other OSTYPE values:  "darwin cygwin msys win32 freebsd"

fi


currD=$(date +"%d")


currW=$(date +"%-W")
if [ $currW -lt 10 ]; then
 currW=" "$currW
fi

currM=$(date +"%-m")
if [ $currM -lt 10 ]; then
 currM=" "$currM
fi



if [ $argcount -eq 0 ]; then

 echo "Current month: $currM"
 ncal -h -b -w -M -m $currM $currY | awk -v dd=$currD -v ww=$currW '{if(match($0,"^" ww)) {print $0"<<<<<<<<<<<< [w="ww",d="dd"]"} else {print $0}}'
 exit

elif [ $argcount -eq 1 ]; then
 #same year
 yend=$1 


  for im in {1..12} ; do ncal -h -b -w -M -m $im $ystt; done  | sed 's/ /-/g' | perl -Mfeature=say -ne 'BEGIN { $sM=(); } chomp($_); if($_ =~ /^-+$/) { $skip=$_;} elsif(  $_ =~ /^-+[A-Z]/) { $sM=$_; } else { say $_ . $sM ; }' 

elif [ $argcount -eq 3 ]; then 
#mode="cal" not "ncal"

echo "ToDo: fix for cal in cygwin, $3"
 for iy in $(eval echo {$ystt..$yend}) ; do for im in {1..12} ; do cal -w -m  $im $iy ;      done ; done | sed 's/ /-/g' | perl -Mfeature=say -ne 'BEGIN { $sM=(); } chomp($_); if( $_ =~ /^-+$/ || $_ =~ /^---[A-Z]/ ) { $skip=$_; say ""; } elsif(  $_ =~ /^----+[A-Z]/ ) { $sM=$_; } else { say $_ . $sM ; }'
# for iy in $(eval echo {$ystt..$yend}) ; do for im in {1..12} ; do ncal -b -w -M -m $im $iy; done ; done | sed 's/ /-/g' | perl -Mfeature=say -ne 'BEGIN { $sM=(); } chomp($_); if($_ =~ /^-+$/) { $skip=$_;} elsif(  $_ =~ /^-+[A-Z]/) { $sM=$_; } else { say $_ . $sM ; }'

 cal -w -m

 exit

else

# ref _ for i in {01..10}; do echo $i; _ yields numbers like 01, 02, 03, ..., 10. 
# ref _ iterate over the range of indices of an array, in bash _ myarray=('a' 'b' 'c'); for i in ${!myarray[@]}; do echo $i; done
# ref _ for iy in $(seq $ystt $yend) ; do for im in {1..12} ; do ncal -b -w -M -m $im $iy; done ; done | sed 's/ /-/g' | perl -Mfeature=say -ne 'BEGIN { $sM=(); } chomp($_); if($_ =~ /^-+$/) { $skip=$_;} elsif(  $_ =~ /^-+[A-Z]/) { $sM=$_; } else { say $_ . $sM ; }'
for iy in $(eval echo {$ystt..$yend}) ; do for im in {1..12} ; do ncal -b -w -M -m $im $iy; done ; done | sed 's/ /-/g' | perl -Mfeature=say -ne 'BEGIN { $sM=(); } chomp($_); if($_ =~ /^-+$/) { $skip=$_;} elsif(  $_ =~ /^-+[A-Z]/) { $sM=$_; } else { say $_ . $sM ; }' 

fi

echo -e "\nCurrent month: $currM\n"

# h switch suppresses highlight
#ncal -M -b -w -h 
ncal -M -b -w 

echo -e  "\nCurrent week: $currW\n"

For the latest version, see

https://github.com/viviparous/showcal