Systemd/timers: Difference between revisions
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Timers are systemd unit files whose name ends in .timer that control .service files or events. Timers can be used as an alternative to <code>cron</code>. Timers have built-in support for calendar-based events and monotonic time events, and can be run asynchronously. | Timers are systemd unit files whose name ends in .timer that control .service files or events. Timers can be used as an alternative to <code>cron</code>. Timers have built-in support for calendar-based events and monotonic time events, and can be run asynchronously. | ||
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<syntaxHighlight lang="nix"> | <syntaxHighlight lang="nix"> | ||
... | ... | ||
timerConfig = { | |||
OnCalendar = "daily"; | OnCalendar = "daily"; | ||
Persistent = true; | Persistent = true; | ||
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systemctl start hello-world | systemctl start hello-world | ||
</syntaxhighlight> | </syntaxhighlight> | ||
[[Category:systemd]] | |||
Revision as of 21:35, 24 April 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";
};
};
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