Systemd timer that expired while suspended

Question

I have created a systemd user timer that expires daily, i.e. at midnight. The problem is that my computer is normally suspended at night. When I wake it up in the morning, I want the timer to trigger, but that doesn't happen. I discovered the Persistent option, but that only helps when the system is powered down, since it triggers expired timers when starting the services. Is there a solution to this other than e.g. running an hourly timer and saving a timestamp to a file somewhere?

Edit 2017-03-17: I'm using systemd 231 on ubuntu 16.10. What I want to is to run remind once a day, preferably when I wake up the computer in the morning.

Answer 1

One option you have is to set WakeSystem=true in your .timer file, which will wake the computer from suspend to run the job.

Then in the .service file that's run, you can add:

 ExecStopPost=sudo /bin/systemctl suspend

To re-resuspend the computer when the job is done running.

You'll also need to update /etc/sudoers to allow your user to run the above command without requiring a password.

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A second option is to use one of the monotonic timers described in man systemd.timer like OnActiveSec=. These timers stop counting time when the computer is suspended. These allow you to express things like "Please backup my computer once every 8 hours that it is on". If your computer is normally on about 8 hours a day, this will roughly correspond to once per day. As you describe, your computer is frequently backed up around midnight anyway-- it's backed up when you first unsuspend it in the morning.

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Third, did you confirm that Persistent= doesn't work with suspend as well when the machine is powered off?

Answer 2

It seems there is no problem with the Persistent option and suspend. The problem seems to be that Persistent=true only works if the timer has had a chance to trigger at least once, i.e. if LAST is not n/a. But my computer is normally suspended at midnight, so the timer has never triggered.