Demystifying Cron Schedules: How to Generate and Debug Linux Crontabs with AI
A complete engineer's reference to cron expressions. Learn crontab syntax, special strings (@daily, @reboot), timezones, and how to generate schedule expressions with AI.
ProfitTool Editorial Team
Technical Editorial & Research
The 5-Field Standard of Linux Cron
Cron is the backbone of automated computing, running scheduled backups, database cleanup jobs, and email batch deliveries. Yet even seasoned DevOps engineers frequently confuse the day-of-month and day-of-week fields.
Standard Crontab Field Breakdown
┌───────────── Minute (0 - 59)
│ ┌───────────── Hour (0 - 23)
│ │ ┌───────────── Day of Month (1 - 31)
│ │ │ ┌───────────── Month (1 - 12)
│ │ │ │ ┌───────────── Day of Week (0 - 6) (0 = Sunday)
│ │ │ │ │
* * * * * <command-to-execute>Paste any expression into the Cron Expression Parser to read the five fields back in plain English before you commit them to a crontab.
Common Cron Cheat Sheet
| Requirement | Cron Expression | Explanation |
|---|---|---|
| Every 15 minutes | */15 * * * * | Runs at :00, :15, :30, :45 past every hour |
| Daily at 2:30 AM | 30 2 * * * | Common backup window off-peak |
| Mon-Fri at 9:00 AM | 0 9 * * 1-5 | Business weekday morning triggers |
| 1st of every month | 0 0 1 * * | Monthly invoicing and rollups |
Verify execution timestamps against UTC with our Unix Timestamp Converter.
Check your cron rules against the Cron Expression Parser before they hit production.
ProfitTool Editorial Team
Technical Editorial & ResearchWritten and maintained by the ProfitTool team. Where an article references a ProfitTool utility, the behaviour described is the behaviour of the tool on this site — you can open it and check the output yourself.
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