- SSH into the OS or use Terminal
- Type date (time will be displayed as 17:30
- Type sudo at 18:00 (this schedules the next command to run in 30 min from 17:30)
- Type your password
- Type shutdown -r now and press Enter (other commands typed will now be scheduled at 18:00, just a reboot is required for now)
- Press CRTL+D
You'll see your task scheduled. You may want to use this when you are running updates on a system and want to automatically reboot. To be on the safe side you will want to schedule the reboot well after updates have had time to run.