#!/bin/sh

set -e

usage() {
	echo "Usage: ${0##*/} [-n] [-l length] [chars]" >&2
	exit 1
}

while getopts 'l:n' o; do
	case "$o" in
	l) len="$OPTARG" ;;
	n) nnl=false     ;;
	*) usage         ;;
	esac
done

shift $((OPTIND - 1))
[ $# -gt 1 ] && usage
</dev/urandom tr -dc -- "${1:-[:graph:]}" | head -c "${len:-64}"
${nnl:-true} && echo