service gdm restart
restart: Rejected send message, 1 matched rules; type="method_call", 
sender=":1.130" (uid=1001 pid=2935 comm="restart) 
interface="com.ubuntu.Upstart0_6.Job" member="Restart" 
error name="(unset)" requested_reply=0 destination="com.ubuntu.Upstart" 
(uid=0 pid=1 comm="/sbin/init"))