Bash Parse Arguments

• Parse with getopts (bash-builtin)
• Parse in ‘while’-loop
• Parse in ‘select’-loop

3 ways to parse arguments with bash scripts

Parse with getopts (bash-builtin)

while getopts "fhm" OPTION; do
   case $OPTION in
      f) FORCE=1 ;;
      h) print_help; exit ;;
      m) BASE="MM" ;;
      *) echo "Unknown Argument $OPTION given"; exit 1;;
   esac
done

Parse in ‘while’-loop

#!/bin/bash

while [ "$1" ]; do
   optarg=""
   opt=""
   case "$1" in
       -*=*) 
          opt=`echo "$1" | sed 's/=.*//'`
          optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'`
       ;;
        *) 
          opt=$1
       ;;
   esac

   case $opt in
       -u)
          shift; # shift the '-u'
          MYUSER=$1
          shift; # shift the val
       ;;

       --user)
          MYUSER=$optarg;
          shift; # shift the '--user=val'
       ;;

       -h|*)
          echo "my help text "
          exit 1
       ;;
    esac
done

echo "\$MYUSER = $MYUSER"
echo "\$Q = $Q"

exit 0

Parse in ‘select’-loop

select opt in $@; do
   if [ "$opt" = "Quit" ]; then
      echo done
      exit
   elif [ "$opt" = "Hello" ]; then
      echo Hello World
   else
      clear
      echo bad option
   fi
done