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Cron every 6 hours

The cron expression for every 6 hours is 0 */6 * * *, running at midnight, 6:00, noon and 18:00. Offsets, uneven steps such as */7, and the GitHub Actions and AWS forms.

Cron expression
0 */6 * * *
See the next run times

The expression

0 */6 * * *

Runs at minute 0 of hours 0, 6, 12 and 18: 00:00, 06:00, 12:00 and 18:00, four times a day.

Field Value Meaning
Minute 0 at minute 0
Hour */6 every 6th hour, starting at 0
Day of month * every day
Month * every month
Day of week * every day of the week

*/6 is the list 0,6,12,18, so 0 0,6,12,18 * * * is identical. The schedule is tied to the clock and restarts at midnight each day.

Variants

Schedule Expression
Every 6 hours from 3:00 (3, 9, 15, 21) 0 3-23/6 * * *
Every 6 hours at 45 past 45 */6 * * *
Every 6 hours, weekdays only 0 */6 * * 1-5
Every 4 hours 0 */4 * * *
Every 12 hours 0 */12 * * *
Once a day at midnight 0 0 * * *

Uneven steps

A step in the hour field always starts over at 0 the next day. 0 */6 works because 24 is a multiple of 6. 0 */7 * * * looks like "every 7 hours" but runs at 0, 7, 14 and 21, and then 00:00 comes after only 3 hours. 0 */5 * * * (0, 5, 10, 15, 20) ends the day with a 4-hour gap. For a real fixed interval that ignores the day boundary, use a systemd timer (OnUnitActiveSec=7h) or AWS rate(7 hours).

Where to write it

  • crontab (Linux, macOS): 0 */6 * * * /usr/local/bin/backup.sh in crontab -e, in the server's time zone.
  • GitHub Actions: on: schedule: - cron: '0 */6 * * *'. UTC; runs at minute 0 can be delayed under load, so an odd minute is safer. This is a common choice for dependency or link checks.
  • Kubernetes CronJob: schedule: "0 */6 * * *", with timeZone: if the four times should be local.
  • AWS EventBridge: cron(0 0/6 * * ? *) (six fields, ? in day of week) or rate(6 hours), which counts from rule creation.

Common mistakes

  • 0 6 * * * runs once a day at 06:00, not every 6 hours.
  • */6 * * * * is every 6 minutes.
  • * */6 * * * runs 60 times during each of the four matching hours.
  • Daylight saving. In a DST zone, the gap across the change is 5 or 7 hours of real time. Schedule in UTC if the interval must be exact.

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