List users of a the specified group(s).

listusers.sh

#!/bin/bash
for group in $@; do
	echo "$group:"
	users=$(awk -F: "/^$group/{print \$4}" /etc/group | tr , \\n | sort)
	if [ "$users" != "" ]; then
		for user in $users; do
			echo "  $user"
		done
	else
		echo "  <no users in this group>"
	fi
done