Cron monthly on the 1st at 09:00: the expression, explained, in Docker

The cron expression for “monthly on the 1st at 09:00” is 0 9 1 * *. This page shows what each field does, the next five times it will fire, the mistake most people make with it, and a working Docker example you can paste.

The expression

0 9 1 * *
FieldValueMeaning
minute0exactly 0
hour9exactly 9
day of month1exactly 1
month*every month
day of week*every day of week

Next five runs (UTC, from now)

  1. 2026-10-01 09:00 UTC
  2. 2026-11-01 09:00 UTC
  3. 2026-12-01 09:00 UTC
  4. 2027-01-01 09:00 UTC
  5. 2027-02-01 09:00 UTC

Mistakes people make with this schedule

  • Adding a day-of-week next to day-of-month 1. Classic cron ORs the two, so "0 9 1 * 1" would also run every Monday. Leave day-of-week as "*".
  • Assuming the server clock is your clock. Cron runs in the machine’s timezone unless the runtime says otherwise; the examples here are UTC.
  • No lock around a job that might overlap itself, and no alert when it silently stops. That second one is what Supercrontab is for.

Run it in your stack

Linux crontabLaravelWordPressNext.js / VercelNode.jsPythonDockerGitHub Actions
# Dockerfile
RUN apk add --no-cache curl
RUN echo '0 9 1 * * curl -fsS http://app:3000/cron/run' > /etc/crontabs/root
CMD ["crond", "-f", "-l", "2"]

Or skip the sidecar: expose the route and let Supercrontab call it.

Questions

Does 0 9 1 * * run in my local time?

Only if the scheduler is configured for it. crontab uses the system timezone; Vercel and GitHub Actions always use UTC; Laravel and node-cron take a timezone option. In Supercrontab the timezone is a field on the job.

What if the previous run is still going?

Classic cron starts the next run anyway. Add a lock (flock on Linux, withoutOverlapping() in Laravel) or let Supercrontab skip the tick while the previous request is open.

Is there a shorter way to write this?

No. The five-field form is the shortest portable version.