0 */2 * * * looks short. On a five-field crontab it means minute 0 of every second hour. The hour field steps from 0, so the day runs at 00:00, 02:00, 04:00, 06:00, 08:00, 10:00, 12:00, 14:00, 16:00, 18:00, 20:00, and 22:00. The last fire that day is 22:00, not 23:00.

Build the same five fields in the cron expression generator . The page does not install the job. Copy the line into the crontab on the host that will run it.

How the step is counted

A step is a range plus /n . In the hour field, * is the full hour range, so */2 walks that range by two, starting at 0. Pin the minute to 0 and you get the top of those hours only.

That is different from every hour:

0 * * * * # every hour, at minute 0 0 */2 * * * # every second hour, at minute 0

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0 * * * * fires 24 times a day. 0 */2 * * * fires 12 times. Neither line has a seconds field.…