- Go to Applications (or Main Menu) > Accessories > Terminal.
-
Enter sudo shutdown -h +m (replace m with the number of minutes, e.g. +60).
OR: enter sudo shutdown -h hh:mm (replace hh:mm with the time on the 24hr clock, e.g. 23:15). - Enter password and minimize the Terminal window.
Alternatively, you might want to download and install GShutdown, which is a GUI program for scheduling a time to shutdown the system.