Command line argument validation library for Bash

Question

I am looking for a reusable code snippet that does command line argument validation for bash.

Ideally something akin to the functionality offered by Apache Commons CLI:<

Answer 1

This is the solution I use (found it on the net somewhere, probably here itself, don't remember for sure). Please note that the GNU getopt (/usr/bin/getopt) does support single dash long options (ant -projecthelp style) using the option -a, however I haven't used it so it is not shown in the example.

This code parses for 3 options: --host value or -h value, --port value or -p value and --table value or -t value. In case the required parameter isn't set, a test for it is

# Get and parse options using /usr/bin/getopt
OPTIONS=$(getopt -o h:p:t: --long host:,port:,table: -n "$0" -- "$@")
# Note the quotes around `$OPTIONS': they are essential for handling spaces in 
# option values!
eval set -- "$OPTIONS"

while true ; do
    case "$1" in
            -h|--host) HOST=$2 ; shift 2 ;;
            -t|--table)TABLE=$2 ; shift 2 ;;
            -p|--port)
                    case "$2" in
                            "") PORT=1313; shift 2 ;;
                            *)  PORT=$2; shift 2 ;;
                    esac;;
            --) shift ; break ;;
            *) echo "Internal error!" ; exit 1 ;;
    esac
done
if [[ -z "$HOST" ]] || [[-z "$TABLE" ]] || [[ -z "$PORT" ]] ; then
    usage()
    exit
if

An alternative implementation using the getopts shell builtin(this only supports small options):

while getopts ":h:p:t:" option; do
    case "$option" in
         h) HOST=$OPTARG ;;
         p) PORT=$OPTARG ;;
         t) TABLE=$OPTARG ;;
        *) usage(); exit 1 ;;
    esac
done
if [[ -z "$HOST" ]] || [[-z "$TABLE" ]] || [[ -z "$PORT" ]] ; then
    usage()
    exit
if

shift $((OPTIND - 1))

Further reading for GNU getopt and getopts bash builtin