To perform a full reboot you can use the systemctl reboot command, but how can you schedule it at a specific time? In this post I explain how to do it using systemd, the boot manager and administration system for Linux distributions.
Among the systemd timer services there’s a little-known feature that allows you to schedule an automatic reboot whenever you want.
Timer for Daily Reboot
I create a reboot-diario.timer file where I request the execution of one of the Systemd Special Units, specifically the “reboot.target” Unit, which allows a shutdown and reboot of my Linux machine.
- File
/etc/systemd/system/reboot-diario.timer
[Unit]
Description=Reboot Diario.
[Timer]
OnCalendar=*-*-* 04:30:00
Unit=reboot.target
[Install]
WantedBy=timers.target
- Enable the new service
systemctl daemon-reload
systemctl enable reboot-diario.timer
systemctl start reboot-diario.timer
From now on, my machine will reboot every day at 04:30 am.
systemd.special
Some units are treated specially by systemd. Many of them have special internal semantics and cannot be renamed, while others simply have a standard meaning and should be present on all systems.
They exist under systemd.special and you can use them when needed. Here’s the explanation for the one I use in this example:
- reboot.target
This is a special target for shutting down and restarting the system. Applications that want to reboot the system should not use it directly, but instead run systemctl reboot (possibly with the –no-block option) or call systemd-logind(8)’s org.freedesktop.login1.Manager.Reboot() D-Bus method directly.
I recommend also looking into the systemd-reboot.service(8) service for more details on the operation this target performs.
This unit has an alias called runlevel6.target for SysV compatibility.