Comment by ww520

1 year ago

Looks nice.

One thing I found systemd really confusing was its treatment of ExecStop in a service script. ExecStart is the command to run when systemd starts the service at system boot up (or when a user tells systemd to start the service). However, ExecStop is run when the starting command has finished running. You have to set RemainAfterExit=yes to have the desired function of running the stop command on system shutdown or on user stopping the service. ExecStop is basically the "on-cleanup" event rather than "to-shutdown-the-service" event.

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ww520

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Cyph0n  1 year ago

I think about them as “on start” and “on stop”.

It is important to keep in mind that systemd is tailored towards daemons. So if your service just runs a command that eventually exits, you need to explicitly tell systemd to treat it differently than a daemon.

Edit: As others noted, you’re probably looking for oneshot + RemainAfterExit.

  • rcxdude  1 year ago

    It is a little asymmetric, because 'ExecStart' is actually normally 'Executable that is the service', not just script that starts the service, but I think that's a hangover from the self-daemonizing approach to init scripts.

    • Cyph0n  1 year ago

      True, but it still makes sense to reason about them this way. Say you have an HTTP server:

      - on start: start the server

      - on stop: do nothing, because you are already terminating the server

      But suppose you need to perform an additional task when the server is terminated. That is where you would add a ExecStop command or script.

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