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regexnumbersmatchdigitsprocmail

Procmail match 4 numbers only in email address

How can I make Procmail match an email address which always has 4 numbers in it?

e.g.

[email protected]

I have read that procmail does not support the modern extended regular expression implementations of repetition, such as 

^To:.[0123456789]{4}@mydomain.com$

So how else would I do it?

Thanks.

Solution

  • If you cannot use limiting quantifiers, just repeat the pattern:

    [0-9][0-9][0-9][0-9]@mydomain[.]com

    This will match 4 digits followed by @domain.com. Note that the . must be either escaped or put into a character class to match a literal dot (a . matches any character but a newline).

    To match a string that starts with To:, followed with any character but a newline and followed with the 4-digit username email, use

    ^To:.[0-9][0-9][0-9][0-9]@mydomain[.]com

    See more details on Procmail regex here.