This topic describes how to configure cron expressions.

Cron expressions are applicable to one-time tasks that need to be completed at a certain time point, recurring tasks, and routine maintenance tasks. A cron expression is a string that represents a set of times. The string is separated by five space characters into six fields, in the format of X X X X X X, of which X is a placeholder of a field. If a field contains multiple values, the values are separated with commas (,). Each field can be a specific value or special characters with logical representations.

Values for fields

The following table lists valid values and supported special characters for each field in cron expressions.

Field Required Value range Allowed special character
Second Yes [0, 59] * , - /
Minute Yes [0, 59] * , - /
Hour Yes [0, 23] * , - /
Day Yes [1, 31] * , - / ? L
Month Yes [1, 12] or [JAN, DEC] * , - /
Week Yes [1, 7] or [SUN, SAT]. If you use [1, 7], 1 stands for Sunday, and 2 stands for Monday. * , - / ?

Special characters

Each field in a cron expression can contain a specific number of special characters. Each special character represents a logical argument.

Special character Description Example
* Indicates all possible values. In the Month field, an asterisk (*) indicates any month. In the Week field, an asterisk (*) indicates any day of a week.
, Lists enumerated values. In the Minute field, 5,20 indicates that the task is triggered once at both the 5th and 20th minutes.
- Indicates a range. In the Minute field, 5-20 indicates that the task is triggered once every minute from the 5th to 20th minute.
/ Indicates increments. In the Minute field, 0/15 indicates that the task is triggered once every 15 minutes from the beginning of an hour. In the Minute field, 3/20 indicates that the task is triggered once every 20 minutes from the 3rd minute of an hour.
? Indicates an unspecified value. Only the Day and Week fields support this character. If either one of the Day and Week fields is specified, the other field must be set to a question mark (?) to avoid conflicts.
L Indicates the last day. Only the Day field supports this character. Do not specify a list or range when using the L character because it may lead to a logical disorder. In the Day field, L indicates the last day of the month.

Value examples

The following table lists some sample values of cron expressions.

Example Description
0 15 10 ? * * Performs the task at 10:15 every day.
0 15 10 * * ? Performs the task at 10:15 every day.
0 0 12 * * ? Performs the task at 12:00 every day.
0 0 10,14,16 * * ? Performs the task at 10:00, 14:00, and 16:00 every day.
0 0/30 9-17 * * ? Performs the task once every half an hour between 09:00 and 17:00 every day.
0 * 14 * * ? Performs the task once every minute between 14:00 and 14:59 every day.
0 0-5 14 * * ? Performs the task once every minute between 14:00 and 14:05 every day.
0 0/5 14 * * ? Performs the task once every five minutes between 14:00 and 14:55 every day.
0 0/5 14,18 * * ? Performs the task once every five minutes between 14:00 and 14:55 and between 18:00 and 18:55 every day.
0 0 12 ? * WED Performs the task at 12:00 every Wednesday.
0 15 10 15 * ? Performs the task at 10:15 on the 15th day of every month.
0 15 10 L * ? Performs the task at 10:15 on the last day of every month.
0 10,44 14 ? 3 WED Performs the task between 14:10 and 14:44 every Wednesday in March every year.