Linux Survival Basics
Read-onlyList Upcoming systemd Timers
Backups, renewals, and cleanup jobs may run as systemd timers, but they are easy to miss if you only inspect cron.
Command
systemctl list-timers --all --no-pagerBefore you run this
System impact: Read-only. Low when scoped to the shown target.
When not to use it: Do not use it to inspect classic cron jobs; check crontabs separately.
Expected output
Timer rows showing NEXT, LEFT, LAST, UNIT, and ACTIVATES.
System impact
Read-only. Nothing changes. systemd prints timer units, next run time, last run time, and the service each timer activates.
Recovery / rollback: no state is changed.
When to use it
Use when checking backups, certificate renewals, cleanup jobs, or unexpected periodic work.
When not to use it
Do not use it to inspect classic cron jobs; check crontabs separately.
Watch this command run
Command transcript
This sanitized transcript shows the commands and output shape without exposing host details.
$ systemctl list-timers --all --no-pager
NEXT LEFT LAST PASSED UNIT ACTIVATES
Thu 2026-06-25 22:00:00 CDT 7h left Thu 2026-06-25 02:00:00 CDT 12h ago backup.timer backup.service
Fri 2026-06-26 00:05:00 CDT 9h left Thu 2026-06-25 00:05:00 CDT 14h ago certbot.timer certbot.service$ systemctl --failed --no-pager
UNIT LOAD ACTIVE SUB DESCRIPTION
backup.service loaded failed failed Nightly backup job
app-worker.service loaded failed failed App background worker
2 loaded units listed.View commands shown
These are the commands shown in the sanitized transcript.
Commands shown
systemctl list-timers --all --no-pagersystemctl --failed --no-pager
next steps
Related commands
Map systemd Timers to Services
A timer is only half the scheduled job. The service is the payload.
systemctl list-timers --all --no-pager --plain | awk 'NR==1 || /\.timer/ {print $(NF-1), "->", $NF}'
Show Failed systemd Units
One command tells you which services systemd already knows are broken.
systemctl --failed --no-pager
Spot Stale systemd Timers
The suspicious timer is the one with no next run.
systemctl list-timers --all --no-pager --plain | awk 'NR==1 || $1=="n/a" || /backup\.timer|logrotate\.timer/'
Read the Failure Cause in systemctl Status
The status page often tells you the failed startup step before you open every log.
systemctl status app-worker --no-pager --lines=50
Compare Failure Output With the Effective Unit
Put the failed step next to the unit config that created it.
systemctl status app-worker --no-pager --lines=50 && systemctl cat app-worker
Study mapping
Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.
Useful for
- LPIC-1 style command-line practice
- LFCS style performance tasks
- Linux+ style troubleshooting review
Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.