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Systemd Timer units (discuss.tchncs.de)

submitted 1 week ago by MoLoPoLY@discuss.tchncs.de to c/linuxquestions@lemmy.zip

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I am trying to create some systemd units that are supposed to start scripts at certain intervals. With Cron, I used an expression like 0 3 */7 * * to start a job every 7 days at 3 a.m. That worked great. With OnCalendar, I have no idea how to implement "every 7 days". Or can I use OnUnitActiveSec here? Additional problem: The computer is not always on at the specified time. The job should therefore be repeated as soon as the computer is available again. I have set Persistent=true for this purpose. However, I suspect that OnUnitActiveSec is reset every time I restart the computer. Or does OnUnitActiveSec refer to the time when the unit was activated with systemctl enabled test.timer?

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[–] HelloRoot@lemy.lol 5 points 1 week ago* (last edited 1 week ago) (2 children)

OnCalendar is calendar-based, not interval-based.

Use a monotonic timer with OnUnitActiveSec=7d plus Persistent=true . This is not quite the same as your cron, because it can drift the day of ghe weak.

And no, it does not reset just because you reboot.

[–] MoLoPoLY@discuss.tchncs.de 2 points 1 day ago (1 children)

It seems that this doesn't work as expected. Please see my new post from today. I have found also the following issue https://github.com/systemd/systemd/issues/3107. According to this, a monotonic timer doesn't survive a reboot or power off. Please correct me, if I'm wrong.

If I understand this correctly, only a onCalendar type can be used here. That's a little bit annoying, but as of yet, I haven't found a way around this.

[–] HelloRoot@lemy.lol 1 points 14 hours ago

oh shit thats really weird systemd design...

[–] MoLoPoLY@discuss.tchncs.de 3 points 1 week ago

Shifting the day of the week is totally fine, since i only care about days between the job executions. Many thx, then i try my luck with this.