There are several good references on systemd timers including this one:


Unfortunately, it still isn't clear to me how to create a timer that will run periodically, but at a specific number of minutes after the top of the hour.

I want to create a timer that runs 30 minutes past the hour, every 2 hours. So it would run at 14:30 (2:30 pm), 16:30, 18:30, 20:30, etc.

I tried several things that did not work, including this:

OnCalendar=*-*-* *00/2:30

And this:

OnCalendar=*-*-* *:00/2:30

I did not find the time specification to produce the desired result.

Also, it does not have to run exactly at that moment, so I was thinking about using:

  • You should use RandomizedDelaySec=5m instead of AccuracySec for the purpose. – Petri Riihikallio Jan 31 '18 at 9:38

Every 2 hours at 30 minutes past the hour should be

#   iow    hh/r:mm

00/2 - the hh value is 00 and the repetition value r is 2 which means the hh value plus all multiples of the repetition value will be matched (00,02,04..14,16..etc)
30 - the mm value, 30 will match 30 minutes past each hour

I left the date and the seconds out since, per the same man page:

date specification may be omitted, in which case the current day [...] is implied [...]If the second component is not specified, ":00" is assumed.

  • Forgive my ignorance, I am still trying to digest the systemd timer grammar... Would every 4 hours be OnCalendar=00/4:00? – user56041 Mar 28 '19 at 22:02
  • @jww - that is correct. As to your other Q - try to specify Unit=ftc-data.service under [Timer] before (or after) OnCalendar... And btw, you don't enable the service, only the timer. – don_crissti Mar 28 '19 at 23:08
  • Thanks @don. Unit=ftc-data.service did not help. Does crontab still work on new Fedora systems? I'm happy use it to avoid dicking around with systemd problems. – user56041 Mar 28 '19 at 23:35

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