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Elastic Compute Service

Appendix

Cron expression

Introduction to Cron expressions

A Cron expression is a string with time semantics. Each time-related component is called a field, and fields are separated by spaces. Auto Scaling scheduled tasks support Cron expressions with 5 fields, in the format X X X X X. X is a placeholder for a field. Each field in a Cron expression represents, in sequence, minute, hour, day, month, and week. Each field can be a specific value or a logical special character.

Usage notes

When you configure a Cron expression for a scheduled task, note that:

Cron expressions are based on UTC +08:00 time zone (China Standard Time). Therefore, when you configure a Cron expression to schedule a task triggered every day at 20:00 in China, set the Cron expression to 0 20 * * *.

Detailed Cron expression rules are listed below. This section only describes commonly used and currently supported Cron expression rules.

Field value range

Field	Required	Value range	Special character
Minute	Yes	0-59	* , - \
Hour	Yes	0-23	* , - \
Day	Yes	1-31	* , - L W
Month	Yes	1-12	* , - \
Week	Yes	1-7	* , - \ L #

Description of special characters

Special character	Explanation	Sample value
*	Indicates all numbers within the value range.	In the month field, * indicates every month.
,	Enumerates possible values.	In the week field, 1,2,5 indicates Monday, Tuesday, and Friday.
-	Specifies a value range.	In the day field, 28-31 indicates the 28th, 29th, 30th, and 31st days of the month.
/	Indicates an increment value.	In the minute field, */5 indicates every 5 minutes starting from minute 0. 3/5 indicates every 5 minutes starting from minute 3.
L	The abbreviation of Last, indicating the last day. This character is only supported in the day and week fields.	In the day field, L indicates the last day of the specified month. In the week field, L indicates the last day of the week (Sunday), and must be used with a specific week number. 6L indicates the last Saturday of the specified month. 4L,5L indicate the last Thursday and Friday of the specified month.
W	Indicates the nearest working day (Monday to Friday) to the specified day in the day field. This character is supported only in the day field.	15W indicates the nearest working day to the 15th of each month. If the 15th is a working day, the target date is the 15th. If it is a Saturday, the target date is the 14th. If it is a Sunday, the target date is the 16th. The nearest working day falls within the current month. For example: When 1W is specified, if the 1st falls on a Saturday, the trigger time is the 3rd (Monday). When 31W is specified, if the 31st falls on a Sunday, the trigger time is the 29th (Friday). W can only be used to specify a single day, but not date ranges. LW indicates the last working day of the current month.
#	Specifies the Nth weekday of each month with a specific number required. After #, only numbers 1-5 are supported. This character is supported only in the week field.	7#2 indicates the second Sunday of the specified month in the week field.

Sample value

The listed examples are based on China Standard Time (UTC +08:00) to explain the meaning of different Cron expressions.

Sample value	Description
15 10 * * *	To trigger a task every day at 10:15
0 /8 * * *	To trigger a task daily at 08:00, 16:00, and 24:00
0 10,14,16 * * *	To trigger a task daily at 10:00, 14:00, and 16:00
15 10 15 * *	To trigger a task at 10:15 on the 15th day of each month
15 10 L * *	To trigger a task at 10:15 on the last day of each month
15 10 * * 6L	To trigger a task at 10:15 on the last Saturday of each month
15 10 * * 6#3	To trigger a task at 10:15 on the third Saturday of each month
10,44 14 * 3 3	To trigger a task at 14:10 and 14:44 on Wednesdays in March every year
15 10 * * 1-5	To trigger a task at 10:15 from Monday to Friday every week
/30 15 * *	To trigger a task every 30 minutes on the 15th day of each month
0 10 15W 3 *	To trigger a task at 10:00 on the nearest working day to March 15 every year

Last updated: 2026.06.18 17:48:27