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Cron every hour

The cron expression for every hour is 0 * * * *, which runs at the top of each hour; @hourly is the same. Variants, common traps, and the GitHub Actions and AWS forms.

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

The expression

0 * * * *

Runs at minute 0 of every hour: 00:00, 01:00, 02:00 … 23:00, every day. That's 24 times a day.

Field Value Meaning
Minute 0 at minute 0
Hour * every hour
Day of month * every day
Month * every month
Day of week * every day of the week

The macro @hourly means exactly the same thing in Vixie cron, cronie and most libraries. The 0 in the minute field is what matters: it picks one minute per hour.

Variants

Schedule Expression
Every hour at half past 30 * * * *
Every hour at a quiet minute 17 * * * *
Every hour, 9 to 5 on weekdays 0 9-17 * * 1-5
Every hour, weekdays only 0 * * * 1-5
Every 30 minutes */30 * * * *
Every 2 hours 0 */2 * * *
Every 6 hours 0 */6 * * *

Where to write it

  • crontab (Linux, macOS): 0 * * * * /usr/local/bin/rotate.sh or @hourly /usr/local/bin/rotate.sh in crontab -e. Many distributions also run scripts dropped into /etc/cron.hourly/, though not necessarily at minute 0 (Debian's /etc/crontab uses minute 17).
  • GitHub Actions: on: schedule: - cron: '0 * * * *'. UTC. The top of the hour is the busiest time on GitHub's schedulers, and their docs warn that runs can be delayed or dropped then, so a minute like 23 * * * * is more reliable.
  • Kubernetes CronJob: schedule: "0 * * * *" or "@hourly"; timeZone: only matters if you narrow the hours.
  • AWS EventBridge: cron(0 * * * ? *). rate(1 hour) also runs hourly, but counted from when the rule was created, so it may fire at :37 instead of :00.

Common mistakes

  • * * * * * with a comment saying "hourly". Without a fixed minute, the job runs every minute.
  • * */1 * * * runs every minute too. */1 in the hour field is just *; the minute field still says "every minute".
  • Daylight saving. In zones with DST, the change days have 23 or 25 hours, so an hourly job runs 23 or 25 times. If you count on exactly 24 runs (hourly buckets, billing), schedule it in UTC.
  • Overlap. A run that sometimes takes over an hour needs flock -n or a concurrency setting.

Paste any expression into the Cron Expression Parser to see it in words and its next run times.