Every day at noon cron: what 0 12 * * * means and how to schedule a midday job

Reading 0 12 * * *

Cron hours run 0–23, so 12 is noon and midnight is 0; there is no AM/PM. Minute 0 pins the start to the top of that hour, and the wildcard date fields make it daily. Writing 0 0 12 * * by mistake puts the 12 in the day-of-month field and runs once a month, on the 12th, at midnight; field order matters more than anything else in cron.

The parser on this page reads it as: At 12:00. The next run times in the panel above are computed in your browser, in your own timezone, so they are not printed in this text.

A midday job in practice

Midday schedules usually exist for people rather than machines: a lunchtime digest email, a status report posted to a chat channel, a reminder. 0 12 * * * /opt/bots/standup-digest --channel ops >> /var/log/digest.log 2>&1 is a typical line. Because the audience is human, the timezone matters more than for a backup, and noon on a UTC server is 17:30 in India and 08:00 or 07:00 in New York depending on daylight saving.

Noon is also safely clear of every daylight saving transition, so the run is never skipped or repeated; it just moves by an hour relative to UTC twice a year if the server follows local time.

Running the same job twice a day

Hours accept lists, so 0 0,12 * * * runs at midnight and noon, and 0 */12 * * * is the same thing. If the job might still be running when the next one starts, the usual guard applies: flock -n /run/lock/digest.lock before the command.

systemd, Kubernetes and GitHub Actions

systemd: OnCalendar=*-*-* 12:00:00, and a timer can name its zone directly, for example OnCalendar=*-*-* 12:00:00 Europe/London. Kubernetes uses schedule: "0 12 * * *" with an optional timeZone. GitHub Actions treats 0 12 * * * as 12:00 UTC. Related: every day at midnight, and every weekday at 09:00 if the job should skip weekends.