Systemd Timer

Sebastian Mangelsdorf

2025-09-06 224 words 2 minutes

Contents

Using systemd timers

Requirements

Two parts working together:

systemd timer
systemd service

Example:

borgmatic.service (i.e. /usr/lib/systemd/system/borgmatic.service)
borgmatic.timer (i.e. /usr/lib/systemd/system/borgmatic.timer)

Adjusting the timer

Default Timer

Listing /usr/lib/systemd/system/borgmatic.timer

[Unit]
Description=Run borgmatic backup

[Timer]
OnCalendar=daily
Persistent=true 
RandomizedDelaySec=3h

[Install]
WantedBy=timers.target

- From the Docs -

Persistent=true If true, the time when the service unit was last triggered is stored on disk. When the timer is activated, the service unit is triggered immediately if it would have been triggered at least once during the time when the timer was inactive.

RandomizedDelaySec=3h Delay the timer by a randomly selected, evenly distributed amount of time between 0 and the specified time value. Defaults to 0, indicating that no randomized delay shall be applied.

Custom Timer

Improvements for a consistent backup schedule.

Listing /usr/lib/systemd/system/borgmatic.timer

[Unit]
Description=Run borgmatic backup

[Timer]
OnCalendar=*-*-* 4:00 #fixed time every morning at 04:00 
Persistent=true
#RandomizedDelaySec=3h # disabled randomization for better monitoring compatibility

[Install]
WantedBy=timers.target#

Applying the changes after editing the file:

systemctl daemon-reload
systemctl restart borgmatic.timer
systemctl status borgmatic.timer

Using Systemd Analyze

If you want to get some more information about a specific setting you can use systemd-analyze

 ╭─traefik@www.vaduzz.de in repo: garden on  main [?] took 0s
 ╰─λ systemd-analyze calendar "4:00"
  Original form: 4:00
  Normalized form: *-*-* 04:00:00
    Next elapse: Sat 2025-09-06 04:00:00 CEST
      (in UTC): Sat 2025-09-06 02:00:00 UTC
      From now: 3h 29min left

References

systemd.time