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I used crontab.guru to create a very simple CRON expression with the desired behavior to execute every day at 3:15 (AM) and this is the result: 15 3 * * *

Crontab.guru

Unfortunately for me, in Azure Portal this does not work, but if I add a leading 0 to my expression as such, 0 15 3 * * *, Azure will accept it, while crontab.guru will tell me it is wrong. The specification according to crontab.guru is: minute hour date month weekday.

Azure does not accept my CRON expression

Azure accepts the expression with a leading zero

The questions..

  • From where comes the discrepancy?
  • Is it Microsoft that in their traditional ways have a proprietary implementation with a leading zero?
  • If the standard is minute hour date month weekday, what does the leading zero describe?
Marcus
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1 Answers1

25

Have a look at the documentation:

The NCRONTAB expression is composed of 6 fields: {second} {minute} {hour} {day} {month} {day of the week}. A CRON expression has only 5, without the seconds.

So the first 0 describes the seconds.

*    *    *    *    *    *  command to be executed
┬    ┬    ┬    ┬    ┬    ┬
│    │    │    │    │    │
│    │    │    │    │    │
│    │    │    │    │    └───── day of week (0 - 7) (0 or 7 are Sunday, or    use names)
│    │    │    │    └────────── month (1 - 12)
│    │    │    └─────────────── day of month (1 - 31)
│    |    └──────────────────── hour (0 - 23)
│    └───────────────────────── min (0 - 59)
└────────────────────────────── second(0 - 59)
StingyJack
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Thomas
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  • Thank you! I realized that it was seconds after a while, but why does it differ from place to place? Are there different standards? Transitional/Strict ? :) – Marcus Jun 16 '16 at 06:58
  • sorry Marcus I don't really know, hopefully someone from the Microsoft team will add a comment ^^ – Thomas Jun 16 '16 at 07:16
  • i have created a webjob recently but it is not triggering automatically even setting correctly the CRON expression, i have also tried creating a settings.job file. What should i do to make it work? – rodrigorf Nov 08 '16 at 10:55
  • Can you create a new question and post your code please ? – Thomas Nov 08 '16 at 19:48
  • Yes there are different standards. See for instance another cronmaker that assumes the seconds is the first: http://www.cronmaker.com/ – Ravit D Jan 03 '17 at 17:50
  • Use this one which follows the same standarts as in webjobs: http://cronexpressiondescriptor.azurewebsites.net/ – Ravit D Jan 03 '17 at 18:06
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    This page has better documentation: https://learn.microsoft.com/en-au/azure/azure-functions/functions-bindings-timer#cron-expressions – ajbeaven Feb 06 '19 at 21:49
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    The second docs page linked has been recently updated (my PR was accepted, yay) to specifically state that these are 6 part NCRONTAB expressions and not the usual 5 part CRON expressions. I've asked for the first link to be corrected in the same way. If the snippet in your answer was from one of those two pages, you may want to update it to match any docs updates. – StingyJack Aug 07 '19 at 14:28