Cron Expression for Every 3 Hours
0 */3 * * *0 */3 * * * runs eight times a day at 00:00, 03:00, 06:00, 09:00, 12:00, 15:00, 18:00 and 21:00 — three divides 24, so the gaps stay exactly three hours across midnight too.
Next runs, in your timezone
Reading the expression
*/3 in the hour field expands to 0,3,6,…,21, minute pinned to :00. Steps that do not divide 24 (say */5 in the hour field) produce one irregular gap at midnight; 3 is not one of them.
0 */3 * * * /path/to/job.sh >> /var/log/myjob.log 2>&1Equivalent expressions
0 0,3,6,9,12,15,18,21 * * *— explicit list — identical schedule0 1-22/3 * * *— same cadence at 01:00, 04:00, …
Run a SQL query on this schedule
If the job behind this schedule is a database query, you can skip the server and the crontab: SaturnSQL runs saved SQL queries on a cron expression — this exact syntax, with a real timezone field — and delivers the results to Google Sheets or Slack. Minimum interval 5 minutes.