How to set up cron expressions-阿里云帮助中心

Cron expressions define schedules for recurring tasks, routine maintenance, and one-time jobs.

A cron expression is a time-based string of six space-separated fields in the format X X X X X X, where each X represents a field value. Separate multiple values in a single field with a comma (,). Each field accepts a specific value or a special character.

Fields and values

The following table describes each field, its allowed values, and supported special characters.

Field	Required	Value range	Special character
Second	Yes	[0, 59]	Not supported
Minute	Yes	[0, 59]	Comma-separated values must be at least 30 minutes apart. Forward-slash increments must be 30 or greater.
Hour	Yes	[0, 23]	* , - /
day-of-month	Yes	[1, 31]	* , - / ? L
Month	Yes	[1, 12] or [JAN, DEC]	* , - /
day-of-week	Yes	[1, 7] or [SUN, SAT]. For the [1, 7] format, `1` represents Sunday, and `2` represents Monday.	* , ?

Special characters

The following special characters are supported in cron expression fields.

Special character	Description	Example
`*`	Matches all values in the field.	In the Month field, `` means every month. In the day-of-week field, `` means every day of the week.
`,`	Lists multiple discrete values.	In the Minute field, `5,40` runs the task at 5 and 40 minutes past the hour.
`-`	Defines a contiguous range of values.	In the day-of-month field, `5-20` runs the task daily from the 5th to the 20th of each month.
`/`	Defines a step interval.	In the day-of-month field, `1/5` specifies the first day of the month and every 5 days thereafter. In the Hour field, `3/8` specifies the 3rd hour and every 8 hours thereafter.
`?`	No specific value. Valid only in the day-of-month and day-of-week fields.	The day-of-month and day-of-week fields are mutually exclusive. If you specify a value in one of these fields, you must use a `?` in the other.
`L`	Stands for “last.” Only supported in the day-of-month field, meaning the last day of the month. Note: Do not combine `L` with a list or range, as this can cause logical conflicts.	In the day-of-month field, `L` means the last day of the month.

Examples

The following table shows common cron expression patterns.

Example	Description
`0 15 10 ? * *`	Runs a task at 10:15 AM every day.
`0 15 10 * * ?`	Runs a task at 10:15 AM every day.
`0 0 12 * * ?`	Runs a task at 12:00 PM (noon) every day.
`0 0 10,14,16 * * ?`	Runs a task at 10:00 AM, 2:00 PM, and 4:00 PM every day.
`0 0/40 9-17 * * ?`	Runs a task at 0 and 40 minutes past the hour, every day, from 9:00 AM to 5:59 PM.
`0 0 12 ? * WED`	Runs a task at 12:00 PM (noon) every Wednesday.
`0 15 10 15 * ?`	Runs a task at 10:15 AM on the 15th of every month.
`0 15 10 L * ?`	Runs a task at 10:15 AM on the last day of every month.
`0 0,30 14 ? 3 WED`	Runs a task at 2:00 PM and 2:30 PM on every Wednesday in March.
`0 0 1 ? * 4#1`	Runs a task at 1:00 AM on the first Wednesday of every month.