CRON expression difference

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1

Hi

Can anyone tell me the difference between cron expression 0 0 12 ? * MON-WED and 0 0 12 * * MON-WED

Thanks in advance

2

Hi @Akshaya89

Expression 1: 0 0 12 ? * MON-WED

  • Executes at 12:00 PM on Monday, Tuesday, and Wednesday.
  • ?: Day-of-month is ignored.

Expression 0 0 12 * * MON-WED

  • Executes at 12:00 PM on Monday, Tuesday, and Wednesday.
  • *: Means β€œevery day of the month.”

? ignores the day-of-month, while * explicitly includes all days.

Hope it helps!!

3

have a look at this online tool which also helps to get more familiar with cron expressions and has a describe functionality

The image shows a cron expression converter displaying a cron schedule that runs at 12:00 PM every day from Monday to Wednesday each month. (Captioned by AI)
The image shows a cron expression converter displaying a cron schedule that runs at 12:00 PM every day from Monday to Wednesday each month. (Captioned by AI)722Γ—180 12.6 KB

And
A user interface displays a cron expression conversion tool, an error message indicating limited support, and options to describe the expression or view next execution dates. (Captioned by AI)
A user interface displays a cron expression conversion tool, an error message indicating limited support, and options to describe the expression or view next execution dates. (Captioned by AI)830Γ—183 13.1 KB

where the role of ? vs * can be derrived and is

This image shows the format and syntax for scheduling tasks using cron job expressions in a UNIX-like system. (Captioned by AI)
This image shows the format and syntax for scheduling tasks using cron job expressions in a UNIX-like system. (Captioned by AI)695Γ—215 3.71 KB

Asterisks (also known as wildcard) represents β€œall”.

The image explains the use of the question mark (?) in cron scheduling, illustrating that some implementations use ? instead of * to signify a blank day-of-month or day-of-week and showing an example where cron updates ? to the start-up time of the cron daemon. (Captioned by AI)
The image explains the use of the question mark (?) in cron scheduling, illustrating that some implementations use ? instead of * to signify a blank day-of-month or day-of-week and showing an example where cron updates ? to the start-up time of the cron daemon. (Captioned by AI)947Γ—110 5.59 KB

taken from: cron - Wikipedia

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