Cron: Run at 9am, 12pm and 3pm
To run a cron job three times a day at 9am, noon and 3pm, use 0 9,12,15 * * *. The hour field takes any comma-separated list, so three values mean three runs.
The expression
0 9,12,15 * * * runs at 9am, 12pm and 3pm every day. Copy it straight into your crontab.
Three runs, one line
0 9,12,15 * * * fires at 09:00, 12:00 and 15:00. Add as many hours as you need — the only rule is to keep the minute fixed (here 0) so each listed hour fires once.
The one mistake to avoid
Put the fixed value 0 in the minute field. If you leave the minute as *, the job runs every minute during each listed hour, not once. The comma list belongs in the hour field; the minute stays a single number.
Limit to weekdays
Append the day-of-week field to restrict the same times to Monday-Friday: 0 9,12,15 * * 1-5.
FAQ
What is the cron expression to run at 9am, 12pm and 3pm?
0 9,12,15 * * * — the comma-separated list in the hour field fires the job once at each listed hour, with minute fixed to 0.
Why does my job run every minute instead of at those hours?
Your minute field is * . A comma list in the hour field still needs a single minute (usually 0), otherwise it runs 60 times per listed hour.
Can I list more than two times in one cron line?
Yes. The hour field accepts any comma-separated list, e.g. 9,12,15 for three runs a day. Keep the minute fixed so each hour fires once.