Cron Expressions

Ptah uses croner for parsing and scheduling. It accepts standard 5- or 6-field expressions; the second-of-minute field is optional.

Field order

┌───────────── second (optional, 0–59)
│ ┌─────────── minute (0–59)
│ │ ┌───────── hour (0–23)
│ │ │ ┌─────── day of month (1–31)
│ │ │ │ ┌───── month (1–12 or JAN–DEC)
│ │ │ │ │ ┌─── day of week (0–7 or SUN–SAT, 0 and 7 are Sunday)
│ │ │ │ │ │
* * * * * *

Common patterns

Expression	Meaning
`* * * * *`	Every minute
`0 * * * *`	Top of every hour
`/15 * * *`	Every 15 minutes
`0 9 * * MON-FRI`	9:00 every weekday
`0 0 * * SUN`	Midnight every Sunday
`0 0 1 * *`	First of every month, midnight
`0 9 1 1 *`	9:00 on January 1st
`30 2 * * *`	2:30 every day

Timezones

Pair every expression with an IANA timezone. 0 9 * * MON-FRI in America/New_York and the same expression in Asia/Tokyo fire at very different absolute times — be explicit.

If you’re unsure what zone string to use, the IANA tzdb list is canonical.