When I SSH in to an Ubuntu based Server, that has automated Security updates enabled, the SSH Splash Screen will show if the server needs a reboot with this message:
*** System restart required ***
Last login: Sun Jan 9 17:44:51 2022 from 10.0.0.100
That is a very handy feature, but only shows up when I log in to the server, so how do I check if the server needs to be rebooted, after I have manually triggered an update?
Well, there is a nifty little trick for that.
If the server needs a reboot, it will create a certain file. Tthat file will be deleted upon reboot. So to check if the server needs a reboot, all I need to do, is check if this file is present.
The file is named reboot-required and if present, can be found in /var/run/
Reboot Required:
username@servername:~$ ls /var/run/reboot-required
/var/run/reboot-required
Reboot not required:
username@servername:~$ ls /var/run/reboot-required
ls: cannot access '/var/run/reboot-required': No such file or directory