xautolock
http://linux.die.net/man/1/xautolock
Цитат
The -killtime and -killer options allow, amongst other things, to implement an additional automatic logout, on top of the automatic screen locking. In the presence of one or both of these options, a secondary timeout will be triggered killmins after starting the locker (unless user activity is detected in the mean time). Upon expiration of this secondary timer, the killer program is run.