Cron explainer

When does it run?

Linux crontab syntax: minute, hour, day of month, month, day of week. Calculated in your browser.

Every 5 minutes Every hour Daily at 02:30 Weekdays at 07:00 Every 15 min, business hours Sundays at 03:00 1st of the month, 06:00 Quarterly Twice a day

At 03:00, on Sunday

0Minute

3Hour

*Day of month

*Month

0Day of week

Next runs (Europe/Vienna)

Sun 2026-10-18 03:00
Sun 2026-10-25 03:00
Sun 2026-11-01 03:00
Sun 2026-11-08 03:00
Sun 2026-11-15 03:00
Sun 2026-11-22 03:00
Sun 2026-11-29 03:00
Sun 2026-12-06 03:00
Sun 2026-12-13 03:00
Sun 2026-12-20 03:00

Times skipped by a daylight-saving change are not listed (cronie runs them right after the switch).

Details

Minute	`0`
Hour	`3`
Day of month	`*`	every
Month	`*`	every
Day of week	`0`	Sun

systemd timer

OnCalendar=Sun *-*-* 03:00:00

Syntax

┌───────────── minute        0–59
│ ┌─────────── hour          0–23
│ │ ┌───────── day of month  1–31
│ │ │ ┌─────── month         1–12 or JAN–DEC
│ │ │ │ ┌───── day of week   0–7 or SUN–SAT (0 and 7 = Sunday)
│ │ │ │ │
* * * * *  command

*: every value
1,15: list
1-5: range
*/15: every 15th value (0, 15, 30, 45)
8-17/2: every 2nd value within a range
@daily: @hourly, @daily, @weekly, @monthly, @yearly, @reboot

If both day of month and day of week are restricted, cron runs when either matches. Cron uses the server's time zone (or CRON_TZ= in the crontab).

Same in the terminal

$ curl tools.otw.solutions/cron/0_3_*_*_0

Or with spaces: curl "tools.otw.solutions/cron?e=0+3+*+*+1-5" · JSON: add ?format=json