#!/bin/sh
set -eu

usage() {
	cat <<-'EOF'
		Usage:
		  uuid
		  uuid -h
	EOF
}

help() {
	cat <<-'EOF'


		Options:
		  -h, --help    show this message


		Generate UUID from /dev/urandom.


		Examples:

		  Generate a UUID:

		    $ uuid
		    755244c8-f955-16df-75cc-f25600c90422
	EOF
}

for flag in "$@"; do
	case "$flag" in
		(--)
			break
			;;
		(--help)
			usage
			help
			exit
			;;
		(*)
			;;
	esac
done

while getopts 'h' flag; do
	case "$flag" in
		(h)
			usage
			help
			exit
			;;
		(*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))

od -xN20 /dev/urandom |
	awk 'NR == 1 { OFS="-"; print $2$3,$4,$5,$6,$7$8$9; exit }'