Let’s say that you ran some updates on your CentOS server but can’t reboot it until a later time, like when users have gone home for the day. Run this simple command to schedule the server to reboot at a certain time. In this case, 8 PM.
sudo shutdown -r 20:00
As indicated in the confirmation received after running the command, you can use this command to override and cancel the scheduled reboot, you can run this command-
sudo shutdown -c
If you stay connected to the SSH or terminal session, you will see this broadcast message at the top of each hour leading up to the reboot.