[systemd-devel] "semaphore" for .timer-triggered run

[Andrei Borzenkov]

02.08.2019 23:24, Johannes Ernst пишет:
> I have a oneshot .service (certbot) that is run by its .timer with:
> 
> OnCalendar=daily
> RandomizedDelaySec=1day
> 
> I also have a sometimes long-running script that may modify the same data. So the script and the oneshot service should never run at the same time.
> 

If script itself runs as oneshot service, then putting After in your
certbot.service should do it (it should wait for prerequisite service to
complete).

> Is there a good systemd pattern for some kind of semaphore-like thing that will delay the execution of the oneshot service and try again when the script is done running?
> 
> I could skip execution, but then I miss an entire day until the service is run again -- I’d prefer it if it tried again a few minutes later. Or I could poll for some flag before running the main part of the service. Wondering whether there something more systemd-native.
> 
> Thanks,
> 
> 
> 
> Johannes.
> 
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