Alerts are scheduled using the crontab syntax. Cron syntax is expressive and can cover a wide range of scheduling scenarios. A few examples are listed below
Schedule |
Description |
Schedules that run Daily |
|
5 * * * * |
This pattern causes a task to be launched once every hour, at the begin of the fifth minute (00:05, 01:05, 02:05 etc.). |
*/5 * * * * |
This pattern causes a task to be launched every 5 minutes (0:00, 0:05, 0:10, 0:15 and so on). |
Schedule that run on specific days |
|
* * * * * |
This pattern causes a task to be launched every minute. |
* 12 * * Mon |
This pattern causes a task to be launched every minute during the 12th hour of Monday. |
* 12 16 * Mon |
This pattern causes a task to be launched every minute during the 12th hour of Monday, 16th, but only if the day is the 16th of the month. Every sub-pattern can contain two or more comma separated values. |
59 11 * * 1,2,3,4,5 |
This pattern causes a task to be launched at 11:59AM on Monday, Tuesday, Wednesday, Thursday and Friday. Values intervals are admitted and defined using the minus character. |
59 11 * * 1-5 |
This pattern is equivalent to the previous one. The slash character can be used to identify step values within a range. It can be used both in the form */c and a-b/c. The subpattern is matched every c values of the range 0,maxvalue or a-b. |
3-18/5 * * * * |
This pattern causes a task to be launched every 5 minutes starting from the third minute of the hour, up to the 18th (0:03, 0:08, 0:13, 0:18, 1:03, 1:08 and so on). |
Schedule that include ranges |
|
*/15 9-17 * * * |
This pattern causes a task to be launched every 15 minutes between the 9th and 17th hour of the day (9:00, 9:15, 9:30, 9:45 and so on... note that the last execution will be at 17:45). All the fresh described syntax rules can be used together. |
* 12 10-16/2 * * |
This pattern causes a task to be launched every minute during the 12th hour of the day, but only if the day is the 10th, the 12th, the 14th or the 16th of the month. |
* 12 1-15,17,20-25 * * |
This pattern causes a task to be launched every minute during the 12th hour of the day, but the day of the month must be between the 1st and the 15th, the 20th and the 25, or at least it must be the 17th. Finally cron4j lets you combine more scheduling patterns into one, with the pipe character: |
