Hi there!

Im trying to figure out how to log off users from a perl script or the command line. I use Debian with gdm and KDE. Up to now, all ive come up with is sending the X Server a HUP signal. But the problem is, that although the X Session is terminated the user remains in the finger table. What I am trying to do is enforce time restrictions in a computer room, so I need info on who is currently logged on to the system. Are there any gdm commands I could send?
Thanks for any information