Cron explainer

When does it run?

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

Every 15 minutes, between 08:00 and 17:59, on Monday through Friday

*/15Minute
8-17Hour
*Day of month
*Month
1-5Day of week

Next runs (Europe/Vienna)

  1. Mon 2026-10-19 08:00
  2. Mon 2026-10-19 08:15
  3. Mon 2026-10-19 08:30
  4. Mon 2026-10-19 08:45
  5. Mon 2026-10-19 09:00
  6. Mon 2026-10-19 09:15
  7. Mon 2026-10-19 09:30
  8. Mon 2026-10-19 09:45
  9. Mon 2026-10-19 10:00
  10. Mon 2026-10-19 10:15

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

Details

Minute*/15every 15
Hour8-178–17
Day of month*every
Month*every
Day of week1-5Mon–Fri

systemd timer

OnCalendar=Mon..Fri *-*-* 08..17:00/15:00

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/*/15_8-17_*_*_1-5

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