user="$1"
if [ -z "$user" ]; then
	if [ "`id -u`" = 0 ]; then
		user=`. who_called_me`
	else
		user=`whoami`
	fi
fi
home="/home/$user"
[ -d "$home" -a "`who_owns "$home"`" = "$user" ] || {
	echo "where is your home directory, $user?"
	exit 1
}