Systemd Service – Timer OnCalendar Every Minute Ending with 5

cronsystemd-service

With OnCalendar systemd timer i can create something like this to run every 5 minutes.

OnCalendar=*:0/5

Is it possible to run it at every minute ending at 5 (00:05, 00:15, 00:25…) only?

And/or at every minute ending with a 0 (00:00, 00:10, 00:20…) only?

Main goal is to have a timer on 2 server, so each one runs at spare times; in case one fails, the other will at least run every 10 minutes (instead of 5).

Best Answer

Solution:

OnCalendar=*:5/10

which is equivalent to *:5,15,25,35,45,55.

To be sure of the result, use something like:

systemd-analyze calendar --iterations=8 '*:5/10' | grep Iter
       Iter. #2: Sun 2022-02-20 00:25:00 CET
       Iter. #3: Sun 2022-02-20 00:35:00 CET
       Iter. #4: Sun 2022-02-20 00:45:00 CET
       Iter. #5: Sun 2022-02-20 00:55:00 CET
       Iter. #6: Sun 2022-02-20 01:05:00 CET
       Iter. #7: Sun 2022-02-20 01:15:00 CET
       Iter. #8: Sun 2022-02-20 01:25:00 CET

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Linux – Minutely cron, ensuring only a single instance

a better way is to use flock instead of a pidfile. check the manpage: flock(1). The advantage is that no matter how a process finishes/dies, the lock is gone with it.

Cron – What does “every two minutes” mean in cron

The job will be run as close to the given time as possible, but may be run slightly later. As Chris suggested, the best thing to do is probably create a small shell script and schedule that instead:

#!/bin/sh
/path/to/job/one &
/path/to/job/two &

In this case I started them in the background to ensure they both run at or nearly at the same time, but depending on your system, your requirements, etc., you will have to adjust this to suit your needs.

Also note that on some systems */2 doesn't actually mean only times divisible by 2, but reoccur in steps equal to 2. So, if the job time matches a 1 when the job is initially started, it may run then every odd minute, as you're seeing, rather than every even one. You could try something like:

00-58/2

to force the job to start on even instances only, but whether and how this works is really dependent on your system, your version of the cron daemon, etc. To get more detailed help, you would have to supply this information :)

Best Answer

Related Solutions

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