Systemd/timers: Difference between revisions

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added alternative example of the call for the binary and command, the quotes confused me when replicating this for rclone (maybe more me but didn't seem like it hurt to add)
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Alternatively here, avoid quotes when calling for the binary and its command options:
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${pkgs.foo}/bin/foo command-options
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This will yield the same result as running
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foo command-options
</syntaxhighlight>
in your terminal.
====Running timer on a schedule====
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Revision as of 17:39, 15 September 2024

Timers are systemd unit files whose name ends in .timer that control .service files or events. Timers can be used as an alternative to cron. Timers have built-in support for calendar-based events and monotonic time events, and can be run asynchronously.

Configuration

The following example timer runs a systemd unit every 5 minutes which invokes a bash script.

systemd.timers."hello-world" = {
  wantedBy = [ "timers.target" ];
    timerConfig = {
      OnBootSec = "5m";
      OnUnitActiveSec = "5m";
      Unit = "hello-world.service";
    };
};

systemd.services."hello-world" = {
  script = ''
    set -eu
    ${pkgs.coreutils}/bin/echo "Hello World"
  '';
  serviceConfig = {
    Type = "oneshot";
    User = "root";
  };
};


Alternatively here, avoid quotes when calling for the binary and its command options:

${pkgs.foo}/bin/foo command-options

This will yield the same result as running

foo command-options

in your terminal.

Running timer on a schedule

The following example starts once a day (at 12:00am). When activated, it triggers the service immediately if it missed the last start time (option Persistent=true), for example due to the system being powered off.

...
  timerConfig = {
      OnCalendar = "daily";
      Persistent = true; 
  };
};

More examples can be found at the Arch Wiki and at the systemd.timer manpage.

Usage

List active timers and their current state:

systemctl list-timers

Manually run a service once for testing purposes:

systemctl start hello-world