Occasionally, you’ll need to reboot (restart) a computer through the command line. Believe it or not, there are multiple death screens before the blue screen of death (cough the black screen with white underscore cough), which make it difficult to safely reboot a computer. Thus, through a Terminal via ssh, you can use
$ sudo reboot
and enter the sudo password. The connection will automatically disconnect, which makes sense because it is restarting. It is always a good idea to use top and nvidia-smi (if there’s a graphics card) to ensure that other users are not in the middle of important jobs or processes. The polite thing in that situation would be to ask if you can reboot, and then proceed with rebooting.