Cron once a week

The expression

0 0 * * 0

Runs once a week, at 00:00 on Sunday. That is what the @weekly macro means, so in a crontab these two lines are identical:

@weekly    /usr/local/bin/cleanup.sh
0 0 * * 0  /usr/local/bin/cleanup.sh

Picking the day and hour

"Once a week" just needs a single value in the day-of-week field and a fixed minute and hour. Sunday at midnight is only the convention behind @weekly; any day works:

Choosing an off-peak, slightly odd time such as 15 3 * * 3 keeps a weekly job away from the crowd of jobs that all start at Sunday 00:00.

Where to write it

• crontab (Linux, macOS): @weekly command or 0 0 * * 0 command in crontab -e, in the server's time zone. Many distributions also run scripts dropped into /etc/cron.weekly/ once a week (through anacron or run-parts), which catches up if the machine was off at the scheduled time.
• GitHub Actions: on: schedule: - cron: '0 0 * * 0'. Macros like @weekly are not accepted; times are UTC. In a public repository, scheduled workflows are disabled after 60 days without repository activity, which a weekly job in a quiet repo can hit.
• Kubernetes CronJob: schedule: "@weekly" or "0 0 * * 0", with timeZone: to set the zone.
• AWS EventBridge: cron(0 0 ? * SUN *), or rate(7 days). A rate counts from when the rule was created, so it runs every 7 days at that time of day rather than on a fixed weekday.

Common mistakes

• * * * * 0 is not weekly. It runs every minute all Sunday: 1,440 times. Fix the minute and hour.
• Assuming @weekly means Monday. It's Sunday at 00:00 in every standard implementation.
• A machine that sleeps. Plain cron skips runs while the computer is off; on laptops and desktops use /etc/cron.weekly, anacron or a systemd timer with Persistent=true.

Paste it into the Cron Expression Parser to see the next weekly runs.