Run a cron job twice a day (9 AM and 9 PM)
“At minute 0 past hour 9 and 21.”
A comma list in the hour field pins two exact run times — here 09:00 and 21:00, the awake-hours pair. Lists beat steps whenever the times you want aren't evenly spaced from midnight: */12 can only give 00 and 12.
0 9,21 * * *Next 5 runs
Computing from your local clock…
Field by field
| Field | Value | Meaning |
|---|---|---|
| Minute | 0 | exactly 0 |
| Hour | 9,21 | at 9, 21 |
| Day of month | * | every value |
| Month | * | every value |
| Day of week | * | every value |
Typical uses
- Morning and evening digest notifications
- Twice-daily sync with a partner system
- Medication/routine reminder systems
Related schedules
Need a different schedule? Build and test any cron expression with live explanation and next-run preview, or read the complete cron syntax guide.