The cron expression for every 30 minutes is */30 * * * *. Here is what each field means, when the job runs next, and how to know if it stops running.
| Field | Value | Meaning |
|---|---|---|
| Minute | */30 | Every 30 minutes: 0 and 30 |
| Hour | * | Every hour |
| Day of month | * | Every day of the month |
| Month | * | Every month |
| Day of week | * | Every day of the week |
*/30 in the minute field is the same as 0,30: on the hour and at half past. 15,45 shifts it by a quarter of an hour.
Cron doesn't tell you when a job is skipped, crashes or hangs. Create a Hyperping healthcheck in cron mode with */30 * * * * and the job's timezone, add one curl to the end of the job, and you're alerted when a run is missed. Free for up to 20 jobs.
Popular cron schedules:
Every minute • Every 5 minutes • Every 10 minutes • Every 15 minutes • Every 30 minutes • Every hour • Every 2 hours • Every 3 hours • Every 4 hours • Every 6 hours • Every 8 hours • Every 12 hours • Every 24 hours
Every day • Every 2 days • Every 7 days • Every week • Every weekday • Every weekend • At midnight • At noon
Start of month • Twice a month • Every quarter • Every 6 months • Every year • Every leap year
During office hours • Overnight • Every spring • Every fall • Every winter • On Christmas • On New Year
Every 2 minutes • Every 3 minutes • Every 5 hours • Every 16 hours
Related: Cron job monitoring, get alerted when a job misses its schedule