Cron expression to run every hour

Field breakdown

The minute field is the single value 0; everything else is a wildcard. The job is therefore due once per hour, at :00 — 24 runs a day. Cron also accepts the shorthand @hourly, which the daemon expands to precisely 0 * * * *.

Do not run it exactly on the hour

Almost every hourly job in the world fires at :00. Log rotation, metric rollups, cache expiries, billing meters and everyone else's crontab all converge on that minute, and shared infrastructure feels it. Unless the schedule is externally mandated, offset it:

17 * * * * /usr/local/bin/hourly-rollup.sh

A minute chosen from the middle of the hour costs nothing, spreads the load and makes your job's entries trivial to spot in a shared log.

Using it

# crontab, both forms are equivalent
0 * * * *  /usr/local/bin/hourly.sh
@hourly    /usr/local/bin/hourly.sh

# Kubernetes CronJob
spec:
  schedule: "0 * * * *"
  timeZone: "Europe/London"

Kubernetes accepts a timeZone field; plain cron does not, and uses the system zone unless the crontab sets CRON_TZ. For an hourly job the distinction rarely matters, since every zone offset is a whole or half hour and the job runs every hour regardless.

Variations