Cron expressions introduction
Cron ist a powerful Unix tool, which allows you to create firing schedules.
There are also existing plenty of tools that helps you to create cron expressions after a preselection. Like this cronmaker.
Here is an example how cron expressions can look like:
|every half an hour||0 0/30 * 1/1 * ? *|
|daily||0 0 0 1/1 * ? *|
|every friday at 18 o´clock||0 0 18 ? * FRI *|