Bash + gnu getopt example

getopt.sh

#!/bin/bash

set -eu
trap 'echo "$NAME: Failed at line $LINENO" >&2' ERR
NAME=${0##*/}

print_help() {
	echo "Usage: $NAME <opts> <args>" >&2
	exit 1
}

getopt -T &>/dev/null && rc=$? || rc=$?
if ((rc != 4))
then
	echo "This script requires gnu getopt" >&2
	exit 1
fi

opts=$(getopt --name "$NAME" --options hf:vd --longoptions help,file:,verbose,debug -- "$@") || print_help
eval set -- "$opts"

declare file verbose=0 debug=0
while (($#))
do
	case $1 in
		-h|--help)    print_help;;
		-f|--file)    file=$2; shift;;
		-v|--verbose) ((++verbose));;
		-d|--debug)   debug=1;;
		--)           shift; break;;
		# Without "set -e" + ERR trap, replace "false" with an error message and exit.
		*)            false  # Should not happen under normal conditions
	esac
	shift
done

${file+echo "File is set: '$file'"}
for i in verbose debug
do
	echo "${i^} value is ${!i}"
done

if (($#))
then
	echo "$# arguments:"
	printf "  %q\n" "$@"
else
	echo "No arguments"
fi