Writing shell scripts - Lesson 13: Positional Parameters

http://linuxcommand.org/wss0130.php

As we discussed before, many programs, particularly ones from the GNU Project, support both short and long command line options. For example, to display a help message for many of these programs, you may use either the "-h" option or the longer "--help" option. Long option names are typically preceded by a double dash. We will adopt this convention for our scripts.

Here is the code we will use to process our command line:

interactive=
filename=~/system_page.html

while [ "$1" != "" ]; do
    case $1 in
        -f | --file )           shift
                                filename=$1
                                ;;
        -i | --interactive )    interactive=1
                                ;;
        -h | --help )           usage
                                exit
                                ;;
        * )                     usage
                                exit 1
    esac
    shift
done