23 0-20/2 * * * — what this cron expression means
The cron expression 23 0-20/2 * * * runs at 23 minutes past every second hour from midnight to 8 PM. Paste it into the tester below to see the next run times, or read the field-by-field breakdown.
Field-by-field breakdown
minute=23, hour=0-20/2 (a range 0–20 with step 2 → 0,2,4,6,8,10,12,14,16,18,20), rest any.
So it runs at 00:23, 02:23, 04:23 … up to 20:23 — eleven times a day. This is the range+step example from the crontab man page.
When it runs
Next runs: the next even hour (from the 0-20 window) at :23.
Edit the expression in the tester above to see how each field changes the schedule — the next run times update instantly.
FAQ
What does 0-20/2 mean in cron?
It's a range with a step: hours 0 through 20, every 2 hours → 0,2,4,…,20. Combined with minute 23 the job runs at :23 past each of those hours.
Why does it stop at 20 and not 22?
The range is explicitly 0-20, so 22 is excluded. Use 0-22/2 or */2 to include the 22:00 slot.