CRON Expressions

The CRON expression format originates from Unix-based systems, where it has been used for quite some time. While it is a powerful syntax for expressing schedules, it can sometimes be a bit confusing.

This article will provide you with a quick cheat sheet for using CRON expressions in Azure.

Format

A CRON expression is simply a string consisting of six fields that each define a specific unit of time.

They are written in the following format:

{second} {minute} {hour} {day} {month} {day of the week}

Acceptable Values

The following values are allowed within each date/time unit placeholder.

Field Allowed Values Description
{second} 0-59
*		 Trigger every {second} second(s)
{minute} 0-59
*		 Trigger every {minute} minute(s)
{hour} 0-23
*		 Trigger every {hour} hour(s)
{day} 1-31
*		 Trigger every {day} day(s) of month
{month} 1-12
*		 Trigger every {month} month(s)
{day of week} 0-6
MON-SUN
*		 Trigger on specific {day of week}

Special Characters

Additionally you can also use the following special characters to build more advanced expressions:

Special Character Description
* Trigger on tick of every time unit
E.g. ‘*’ in {day} means every day of the month
, List separator
E.g. ‘1,2’ in {month} means every first and second month of the year
– Specifies a range
E.g. ‘5-7’ in {day} means fifth, sixth and seventh of the month
/ Defines an increment
E.g. ‘*/10’ in {minute} means every ten minutes.

Examples

Expression Description
0 * * * * * Executes every minute
0 0 * * * * Executes every hour
0 0 0 * * * Executes every day
0 0 0 0 * * Executes every month
0 0 0 1 1 * Executes on first day of Jan
each year
0 30 20 * * SAT Executes at 08:30pm every Saturday
0 30 20 * * 6 Executes at 08:30pm every Saturday
0 30 8 * * 1-5 Executes at 08:30am Monday to Friday
0 30 20 * * 1-5 Executes at 08:30pm Monday to Friday
0 */5 * * * * Executes every five minutes
0 0 8-10/1 * * * Executes every hour between
8am and 10am

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