genpass

#!/bin/bash

LEN=12
TYPE="[:graph:]"

function help {
	echo "Usage: $0 [-l <length>] [-t <type>]"
	echo
	echo "Types:"
	echo "  alpha:  all letters"
	echo "  alnum:  all letters and digits"
	echo "  digits: all digits"
	echo "  graph:  allprintable characters, not including space "
	echo
	echo "If no options are specified '-l 12 -t graph' will be used."
}

while getopts ":l:t:h" opt; do
	case $opt in
	l)
		re='^[0-9]+$'
		if ! [[ $OPTARG =~ $re ]] ; then
			echo "Option -l requires a numeric argument.";
			exit 1;
		fi
		LEN=$OPTARG
		;;
	t)
		found=0;
		TYPES=(alnum alpha digit graph);
		for i in "${TYPES[@]}"
		do
			if [ "$i" == "$OPTARG" ] ; then
				TYPE="[:$OPTARG:]"
				found=1;
			fi
		done

		if [ "$found" -eq "0" ] ; then
			echo "Invalid argument for option -t";
			exit 1;
		fi
		;;
	h)
		help;
		exit 1;
		;;
	\?)
		echo "Invalid option: -$OPTARG"
		exit 1;
		;;
	:)
		echo "Option -$OPTARG requires an argument."
		exit 1
		;;
	esac
done

echo `env LC_CTYPE=C tr -dc $TYPE < /dev/urandom | head -c $LEN`