parsing command line arguments in bash

gistfile1.sh

function usage() {
    echo ".$0 --argument=foo --argument-two=bar"
    exit 1
} 

while [ "$1" != "" ]; do 
    param=${1%=*} 
    value=${1#*=} 
    case $param in
        --argument)     argument=$value 
                        ;; 
        --argument-two) argument_two=$value 
                        ;; 
        * )             usage
                        ;; 
    esac 
    shift 
done

Y U NO GETOPT?

usage="usage: $0 -a <arg A> -b <arg B>"

while getopts ":a:b:" options; do
   case $options in
      a ) argA=$OPTARG;;
      b ) argB=$OPTARG;;
      * ) echo $usage
            exit 1;;
   esac
done

if [[ -z $argA ]] || [[ -z $argB ]]; then
   echo $usage
   exit 1
fi

@nmilford the pain of getopts is that single variable options are cryptic. They work great for tools like grep that are used by a million people, but they are absolutely terrible for custom scripts. long args foster clear and descriptive (translation: useful) shell scripts.