[linux] Crontab Day of the Week syntax

In crontab does the Day of the Week field run from 0 - 6 or 1 -7?

I am seeing conflicting information on this. wikipedia states 0-6 and other sites I have seen are 1-7.

Also what would be the implication or either using 0 or 7 incorrectly? i.e. would the cron still run?

You can also use day names like Mon for Monday, Tue for Tuesday, etc. It's more human friendly.

    :-) Sunday    |    0  ->  Sun
                  |  
        Monday    |    1  ->  Mon
       Tuesday    |    2  ->  Tue
     Wednesday    |    3  ->  Wed
      Thursday    |    4  ->  Thu
        Friday    |    5  ->  Fri
      Saturday    |    6  ->  Sat
                  |  
    :-) Sunday    |    7  ->  Sun

As you can see above, and as said before, the numbers 0 and 7 are both assigned to Sunday. There are also the English abbreviated days of the week listed, which can also be used in the crontab.

Examples of Number or Abbreviation Use

15 09 * * 5,6,0             command
15 09 * * 5,6,7             command
15 09 * * 5-7               command
15 09 * * Fri,Sat,Sun       command

The four examples do all the same and execute a command every Friday, Saturday, and Sunday at 9.15 o'clock.

In Detail

Having two numbers 0 and 7 for Sunday can be useful for writing weekday ranges starting with 0 or ending with 7. So you can write ranges starting with Sunday or ending with it, like 0-2 or 5-7 for example (ranges must start with the lower number and must end with the higher). The abbreviations cannot be used to define a weekday range.