PatternCron
Twice a day
Morning and evening runs from one expression: the comma list 9,18 in the hour field — cron's way of saying "at these exact values".
Last updated
In plain English
- Fires at 09:00 and 18:00 every day
- 730 runs per year
Why it’s written this way
A comma list enumerates exact values: hour 9 and hour 18, nothing between. Lists are the right tool when the values aren't evenly spaced — a step like */9 would land on 0, 9, 18 and drag in the midnight run you didn't ask for.
Lists, ranges and steps also combine (9-17/2 means every other hour of the working day), which is where cron's five fields get their surprising range.
Edge cases to know
- →The two runs share one command and one environment — if morning and evening need different behaviour, that's two crontab lines, not one cleverer expression.
- →As always the hours are the server's clock; a "9 am and 6 pm" promise to users in another timezone needs the TZ decided first.