#!/bin/bash

function usage
{
	retval="$1"
	case "$retval" in
		0)
			;;
		*)
			exec 1>&2
			;;
	esac
	echo "Usage: $0 --help"
	exit "$retval"
}

while [ "$#" -ge 1 ]
do
	case "$1" in
		-h|--help)
			usage 0
			;;
		*)
			echo "$0: unrecognized option: $1" 1>&2
			usage 1
			;;
	esac
	shift
done

echo 'Hello world!'