Reference category
Time & scheduling
A cron expression is a compact schedule with five independent fields: minute, hour, day of month, month and day of week. The two day fields are ORed in the traditional implementation, and the definition of a day boundary depends on the timezone of the host running the job — two facts behind most “it ran at the wrong time” reports.
The entries cover field order, ranges, steps, names and the common schedules people actually deploy. Read the timezone of the scheduler before changing the expression, and test the next run times rather than reasoning about them in your head.
Reference sets in this category (1)
All 10 entries
Cron Expression Reference 10 entries
Cron field orderA five-field cron expression runs minute, hour, day-of-month, month and day-of-week, in that order.
Cron step valuesA slash adds a step to a range: */5 means every fifth value starting at the range's lower bound.
Cron ranges and listsCommas combine values and hyphens define inclusive ranges; both can be mixed and both may use month or weekday names.
Month and weekday namesCron accepts JAN–DEC and SUN–SAT, case-insensitively, but the numbering of Sunday differs between dialects.
Day-of-month and day-of-week togetherWhen both day fields are restricted, Vixie-style cron runs the job if either field matches.
Cron special stringsMacros such as @daily and @reboot replace common five-field schedules in Vixie-style cron.
Cron and time zonesCron schedules run in the system's local time zone unless the implementation offers CRON_TZ or TZ support.
Cron vs systemd timersCron is one line per job; systemd timers separate a unit from its schedule and can catch up on missed runs.
Six-field cron dialectsQuartz, Spring, AWS EventBridge and Jenkins extend cron with seconds or other fields, and they do not agree on order.
Common cron schedulesThe expressions people ask for most: every five minutes, hourly, daily, weekdays at 09:00 and first of the month.