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Every rule has one schedule, chosen from three modes. Pick the mode that matches how you think about the job.

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Interval

Run every N seconds, minutes, hours or days. The simplest option — “every 15 minutes”, “every 6 hours” — with no cron syntax to remember. Set the number and the unit, and Cronch counts from when the rule starts.

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Cron

For calendar-based timing — “at 9:00 every weekday”, “on the 1st of the month” — use a cron expression.
  • 5 fields (minute hour day-of-month month day-of-week) is standard cron; seconds are assumed to be 0. Example: 0 9 * * * runs at 09:00 every day.
  • 6 fields adds a leading seconds field for finer timing.
New to cron? Start from the example in the field (0 9 * * *) and change one part at a time. Interval mode is often easier for “every so often” jobs; cron shines for “at this clock time”.

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Once

Run a single time at a specific date and time — YYYY-MM-DD HH:MM, in your local time. Useful for a one-off reminder script or a delayed task. After it runs, the rule is done.

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Catch-up: jobs missed while the machine was off

Computers sleep and shut down, so a scheduled time can pass while Cronch isn’t running. Each rule has a Catch up if missed option (on by default) that decides what happens next:
  • On — when Cronch next starts, a rule that came due while it was away runs once, right away. Multiple missed occurrences are coalesced into that single catch-up run, so a weekend of hourly jobs doesn’t fire dozens of times at once.
  • Off — the missed occurrences are skipped; the rule simply waits for its next scheduled time.
A Once schedule that was missed always runs on the next start — that’s the whole reason you set it.
Cronch re-checks its schedule continuously, so clock changes and sleep/wake are handled without relying on operating-system power events. You don’t need to configure anything for this.

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Commands & shells

What actually runs, in which shell, and what to do about overlap.

History & logs

Confirm a schedule is firing by checking its run history.