Expressions
CRON expression is a character string which is split into five separate segments. Each segment serves a distinct purpose:
| Expression | Description |
|---|---|
Minute | Definition at which minutes of an hour a job will be executed. Valid values are between 0 and 59. |
Hour | Definition at which hours of a day the job will be executed. Valid values are between 0 and 23. |
| Definition on which days of a month the job will be executed. Valid values are between 1 and 31. |
Month | Definition on which months of a year the job will be executed. Valid values are between 1 (January) and 12 (December). Following symbols are allowed as well: jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov and dec. |
Day of the Week | Definition on which days of a week the job will be executed. Valid values are between 0 (Sunday) and 6 (Saturday). Following symbols are allowed as well: sun, mon, tue, wed, thu, fri and sat. |
The star wildcard is supported, representative for each minute of an hour, each hour of a day, each day of a month, each month of a year, and each day of the week in relation to the corresponding partial expression. As soon as the scheduler is active, the job is executed when all criteria of the five partial expressions are fulfilled.
Examples
| Example | Description |
|---|---|
5 * * * * | This expression executes the job always five minutes past the hour (00:05, 01:05, 02:05, etc.). |
* * * * * | This expression executes the job every minute. |
* 12 * * mon | This expression executes the job every Monday once per minute during the twelfth hour of the day. |
* 12 16 * mon | This expression executes the job every Monday once per minute during the twelfth hour of the day if the day is the 16th of the month. Each partial expression can contain two or more comma separated values. |
59 11 * * 1,2,3,4,5 | This expression executes a job at 11:59 on Monday, Tuesday, Wednesday, Thursday, and Friday. Intervals of values are also possible. They are defined by a minus sign. |
59 11 * * 1-5 | This expression corresponds to the previous expression. A forward slash can be used to define periodical values (such as a/b). A partial expression with a forward slash is considered fulfilled if the value on the left side divided through the value on the right side equals an integer (a% b == 0). |
*/15 9-17 * * * | This expression executes a job every 15 minutes between 9 a.m. and 5 p.m. (09:00, 09:15, 09:30, 09:45, etc. The last execution is at 17:45). The syntax rules described above can be used together. |
* 12 10-16/2 * * | This expression executes the job each minute during the twelfth hour of the day, on the 10., 12., 14., and 16. of each month only. |
* 12 1-15,17,20-25 * * | This expression executes the job each minute during the twelfth hour of the day if the day is between the 1st and the 15th or between the 20th and the 25th or on the 17th day of the month. CRON permits the combination of expressions by using the pipe sign (|): |
| This expression executes the job every day at 05:00, 10:08, and 17:22. |
A very detailed description about the common CRON syntax can be found on Wikipedia on this page https://en.wikipedia.org/wiki/Cron.