This article demonstrates how to tell a Linux server to shutdown or reboot in a set number of minutes or hours from now. For example, suppose you have a Linux server that needs a reboot for updates to apply but you want to go to lunch – and people are still on it. This is the solution. We need to tell logged-in users about the pending reboot or shutdown.
Reboot in 10 minutes. (the -r means reboot)
shutdown -r +10 "Rebooting in 10 minutes. Go have some lunch."
Reboot in 1 hour.
shutdown -r +60 "Rebooting in 1 hour. You can log back in after the reboot."
Shutdown in 15 minutes. (the -h means halt/shutdown)
shutdown -h +15 "Shutting down in 15 minutes. Be a dear and log out before then."