FreeBSD 15 – cron job does not run at scheduled time – Fix & Prevention

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Scheduled task never triggers, causing backup, cleanup, or reporting workflow gaps.

Environment & Reproduction

Usually caused by malformed crontab lines, PATH assumptions, or daemon not running.

service cron status
crontab -l
cat /etc/crontab

Root Cause Analysis

Cron parser rejects entries silently or script exits due to missing environment variables.

Quick Triage

Check logs for cron invocation and command execution errors.

grep -i cron /var/log/messages | tail -n 80
which sh
ls -la /usr/local/bin

Step-by-Step Diagnosis

Run job script manually using cron-like shell environment.

env -i PATH=/usr/bin:/bin:/usr/sbin:/sbin sh -c '/usr/local/bin/job.sh'
crontab -l | nl -ba

Solution – Primary Fix

Fix crontab syntax, use absolute paths, and ensure executable permissions.

chmod +x /usr/local/bin/job.sh
( crontab -l; echo '*/15 * * * * /usr/local/bin/job.sh >> /var/log/job.log 2>&1' ) | crontab -
service cron restart

Solution – Alternative Approaches

Move critical jobs to periodic framework or dedicated scheduler with retry and observability.

Verification & Acceptance Criteria

Job runs on schedule and produces expected output with zero syntax warnings.

tail -n 50 /var/log/job.log
grep CRON /var/log/messages | tail -n 20

Rollback Plan

Restore previous crontab snapshot if adjusted schedule introduces duplicate execution.

Prevention & Hardening

Lint cron entries in CI and monitor missed-job metrics with alerting thresholds.

Related Errors & Cross-Refs

Related to periodic load spikes and script permission-denied incidents.

Related tutorial: View the step-by-step tutorial for freebsd-15.

View all freebsd-15 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

cron(8), crontab(5), and FreeBSD task scheduling documentation.