Practical guides to truly understand cron and make fewer mistakes
The core concept of the scheduler and the 5-field structure
Day-of-week/day-of-month conflicts, interval misconceptions, overlapping jobs
Server UTC vs. local time, setting TZ
When to use a different scheduler instead of crontab
Capturing output, MAILTO, and a log-checking checklist
crontab -e, environment differences, system vs. user crontab