sub map_user_group
{
	if( ! defined( $uid ) ){
		if( $user =~ /^\d+$/ ){
			# User is just a number - presume it is the uid
			$uid = $user;
		}
		else {
			$uid = (getpwnam( $user ))[ 2 ];
		}
	}
	if( ! defined( $gid ) ){
		if( $group =~ /\d+$/ ){
			# Group is just a number - presume it is the gid
			$gid = $group;
		}
		else {
			$gid = (getgrnam( $group ))[ 2 ];
		}
	}
}