I would like my children to only use the computer for 30 minutes, at which time I would like the screen to be locked. At that point, if I choose to unlock the screen again, I would like the screen to lock again in another 30 minutes.
How can I write a script to do this?
To lock the screen from the command line (on ubuntu), I can use the command
gnome-screensaver-command -l
but how do I activate this command 30 minutes after unlock?