Since version 1.8.0, Issue Reminders add-on support cron expression as period specification. This guide will helps you to understand how it works but you can use any other tutorial on cron expressions because it is a standard, not specific to Issue Reminders.
A cron expression consist of 5 parts.
|MIN||Minute field||0 to 59|
|HOUR||Hour field||0 to 23|
|DOM||Day of Month||1-31|
|DOW||Day Of Week||0-6 (Sun, Mon, Tue, Wed, Thu, Fri, Sat)|
Things to Know
Resolution of all reminders are 5 minutes, so you can't create a reminder with a period of less than 5 minutes. Even if you can write a cron expression it will not fire every minute, it will only fire at every 5 minutes.
Example Cron Expressions
|0 0 * * *||Every hour, for example 13:00, 14:00.|
|30 0 * * *||Every half an hour, for example 13:30, 14:30.|
|0 0 * * *||Same with 1st example. Every hour.|
|0 0 1 1 *||Every year at 12:00 AM on 1 of January.|
|0 7 L * *||Last day of every month at 07:00 AM.|
|0 19 * * 1||Every Monday on 19:00.|
|30 8 1-7 * 1||First Monday of every month at 08:30 AM.|
|15 10 * * 1,5||Every Monday and Friday at 10:15 AM.|
|15 10 * * 1-5||Every weekday (Mon-Fri) at 10:15 AM.|
|0 0 1 1,6 *||At 00:00 on day-of-month 1 in January and June.|
|* * * * * ||Every minute. But not valid for Issue Reminders add-on. It will only work with a period of 5 minutes as explained at Things to Know Section.|
* 0 * * *
|Every minute between 12:00 AM and 01:00 AM of every day. It will only work with a period of 5 minutes as explained at Things to Know Section.|