Cron debugging, systemd timers, and GitHub Actions — practical guides that link straight to the builder when you need to validate an expression.
No error, no log, no clue — the #1 cause is PATH (cron doesn't load .bashrc). Includes a 60-second diagnostic checklist and all 10 fixes with exact commands.
Cron: 1 line, zero setup. systemd timers: journald logging, missed-run recovery & dependency control. Side-by-side syntax, copy-paste examples, and a clear decision guide.
GitHub Actions cron is UTC-only, enforces a 5-minute minimum, and silently delays up to 30 min. All 5 gotchas explained with tested YAML workarounds you can copy-paste.
Every operator, all the @shorthands, 30+ common patterns, and platform differences (Unix, Quartz, AWS EventBridge, Kubernetes, GitHub Actions) — the only cron reference you need to bookmark.
5 methods for validating cron expressions before they reach production — from online testers to dry-run crontab commands, Python's croniter, Node.js unit tests, and monitoring pings.