Out of curiosity, and to check if I understand the systemd concepts properly...
assuming the two units to lock are both systemd services and are both of type oneshot, would a simple After= of one on the other be enough to guarantee they never run together ? Le mar. 27 août 2019 à 12:56, Lennart Poettering <lenn...@poettering.net> a écrit : > On Fr, 02.08.19 13:24, Johannes Ernst (johannes.er...@gmail.com) wrote: > > > 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. > > > > 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. > > Maybe change the service program invoked by the timer unit to use file > locking of some kind early on. I mean, if you have shared data on disk > and want to synchronize access to it then a file lock is the concept > of choice really. If this is a proper program (i.e. not a shell > script) maybe just use a BSD file lock (flock(2)) on the top-level > directory you store your data in. If these are shell scripts you > should be able to use util-linux' flock tool, you could even prefix > your ExecStart= line with that if you want. > > But no, systemd does not provide any mechanism to do file locking for > you. > > Lennart > > -- > Lennart Poettering, Berlin > _______________________________________________ > systemd-devel mailing list > systemd-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/systemd-devel -- [image: SMILE] <http://www.smile.eu/> 20 rue des Jardins 92600 Asnières-sur-Seine *Jérémy ROSEN* Architecte technique [image: email] jeremy.ro...@smile.fr [image: phone] +33 6 88 25 87 42 [image: url] http://www.smile.eu [image: Twitter] <https://twitter.com/GroupeSmile> [image: Facebook] <https://www.facebook.com/smileopensource> [image: LinkedIn] <https://www.linkedin.com/company/smile> [image: Github] <https://github.com/Smile-SA> [image: Découvrez l’univers Smile, rendez-vous sur smile.eu] <https://www.smile.eu/fr/publications/livres-blancs/yocto?utm_source=signature&utm_medium=email&utm_campaign=signature>
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