A CRON expression is a string consisting of six or seven subexpressions (fields), separated by white space, that describe individual details of the schedule.

A very useful tool that enables users to schedule tasks to run periodically at a specified date/time in the future, thus allowing the automation of a lot of tasks and processes that otherwise would require human intervention or another type of coordination.

 Basics

The order of the six fields in Azure is:
`{second} {minute} {hour} {day} {month} {day of the week} { year (optional)}`.

Examples

A CRON expression that can be used as a trigger that executes every three minutes looks like: 0 */3 * * * *.

Or a CRON expression that executes “at minute 5 past every hour from 4 through 7 in February and March”, looks like: `5 4-7 * 2,3 *` (details).

Special character Meaning Example
* Selects every value in a field An asterisk “*” in the day of the week field means every day.
, Separates items in a list A comma “1,3” in the day of the week field means just Mondays (day 1) and Wednesdays (day 3).
Specifies a range A hyphen “10-12” in the hour field means a range that includes the hours 10, 11, and 12.
/ Specifies an increment A slash “*/10” in the minutes field means an increment of every 10 minutes.

Tools

CRONTab Guru

In my opinion, the best tool out there to write and validate your cron schedule expressions:

 

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