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Read-only first

systemd timer not running

Inspect timer schedule, status, unit file, and recent journal entries before enabling, starting, or editing timers.

Safest first command

systemctl list-timers --all --no-pager

Before you run this

Expected output: Timer table with next run, last run, timer unit, and activated service unit.

When not to use it: Do not start or enable timers before confirming the intended timer and service unit.

Expected output example

NEXT LEFT LAST PASSED UNIT ACTIVATES
Mon 2026-07-06 00:00 CDT 5h Sun 2026-07-05 00:00 CDT 19h backup.timer backup.service

How to read the result

NEXT and LAST show scheduling. UNIT is the timer; ACTIVATES is the service it starts.

What to check next

Timer absent from list

Means: The timer may not be installed, loaded, or enabled.

Next step: Read status for the expected timer.

Read One systemd Timer Status

Timer present but LAST is never

Means: It may be disabled, newly created, or not reached since boot.

Next step: Read unit file and journal.

Show systemd Timer Unit File

Timer fired but task did not run

Means: The activated service unit may be failing.

Next step: Read recent timer logs.

Read Recent systemd Timer Logs

Timer decision tree

Separate the timer schedule from the service it activates. The timer can be healthy while the service fails.

  1. systemctl list-timers --all --no-pager
  2. systemctl status backup.timer --no-pager
  3. systemctl cat backup.timer
  4. journalctl -u backup.timer --since "24 hours ago" --no-pager

Bad fixes to avoid

Do not enable every matching timer, edit vendor units directly, or manually run the service before proving schedule and unit linkage.

Common causes

  • Timer disabled or not loaded.
  • Wrong OnCalendar expression.
  • The activated service fails.
  • Drop-in override changes schedule.

What not to change yet

  • Do not edit unit files before reading drop-ins.
  • Do not start the service on production data without checking what it does.

Stop and escalate if

  • The next step could interrupt users, remove data, or lock out access.
  • The output includes secrets, customer data, or private infrastructure details.
  • You cannot explain the blast radius of the repair command.

supporting commands

Command path

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