0 */6 * * * — what this cron expression means
The cron expression 0 */6 * * * runs every 6 hours (4 times a day). Here is the field-by-field breakdown and what it means in plain English.
What 0 */6 * * * means
It runs every 6 hours (4 times a day).
Field by field
minute=0, hour=*/6 → 0,6,12,18; rest *.
Four runs a day at 00:00, 06:00, 12:00 and 18:00 — a common cadence for backups and syncs.
When it runs next
Next runs: the next of 00:00, 06:00, 12:00, 18:00.
FAQ
What does 0 */6 * * * mean?
It runs every 6 hours on the hour: at midnight, 6 AM, noon and 6 PM.
Why does my */6 job not fire exactly every 6 hours after a reboot?
It fires on the fixed clock hours 0/6/12/18, not 6 hours after boot. The gap after a restart can be shorter than 6 hours.