Display reboot required message on Debian

You can use MOTD (message of the day) to let you know if a Debian server requires reboot and why upon login.

Create a new file named /etc/update-motd.d/98-reboot-required and add to it the following lines:

#!/bin/sh -e
# helper for update-motd

if [ -f /var/run/reboot-required ]; then
	echo "*** System restart required ***"
        cat /var/run/reboot-required.pkgs

Make the file executable:

$ sudo chmod +x /etc/update-motd.d/98-reboot-required

Now, you can test the new MOTD script using:

$ run-parts --lsbsysinit /etc/update-motd.d

If you have any installed updates that require reboot, you will get a message stating so, with a list of the packages that require the reboot.

*** System restart required ***