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Thread: [RESOLVED] Regex help please

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  2. #2
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    Re: Regex help please

    That regex looks a bit fishy to me. It says match any character 0 or more times, and then match a forward slash, then match the "thum" followed by the letter "b" 0 or more times.

    Are you on a Windows or Linux filesystem? Or are the paths URLs?
    Are you trying to match any folders that are exactly "thumbnail" or "derivative"?
    Would you want to match folders named "thumb", "thumbnail", "thumbnails", "thumbelina", etc...?
    What about a folder named "green_thumb"?
    What if there's a file named "thumb.jpg" in the "C:\thumbnail" folder? Should it be included or excluded?

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    Former Admin/Moderator MartinLiss's Avatar
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    Re: Regex help please

    • Are you on a Windows or Linux filesystem?==> macOS
    • Or are the paths URLs?==> No they are file paths
    • Are you trying to match any folders that are exactly "thumbnail" or "derivative"==> I want to exclude things like blah/thumbnails/Spain and blah/derivatives/Peru
    • What about a folder named "green_thumb"?==>Not a possibility
    • What if there's a file named "thumb.jpg" in the "C:\thumbnail" folder? Should it be included or excluded?==>Any path with /thumbnail in it should be eliminated. And the .*/thumb* does that.

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    Re: Regex help please

    OK, I wanted to clarify whether you should be using forward or backslashes. MacOS uses forward slash for path separators, so thanks for the clarification.

    */thumb will exclude a lot more than just folders named "thumbnail". It will also exclude file names that start with "thumb". I think this will work better:

    (\/thumbnail(s?)(\/|$)|\/derivative(s?)(\/|$))

    That will match folders named "thumbnail", "thumbnails", "derivative", and "derivatives".

  5. #5
    PowerPoster wqweto's Avatar
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    Re: Regex help please

    Why escape the forward slash? (Edit: I guess it makes sense escaping it in any language with regex literals like Perl or JS)

    A somewhat more explicit regex:

    /(thumbnail|thumbnails|derivative|derivatives)(/|$)

    Hope it's obvious how to include more directories in the check.

    cheers,
    </wqw>

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    Re: Regex help please

    Quote Originally Posted by wqweto View Post
    Why escape the forward slash? (Edit: I guess it makes sense escaping it in any language with regex literals like Perl or JS)
    Yeah, I'm one of those weirdos that uses Perl a fair bit, so force of habit I guess.

    I was also testing with some random online regex tester that must be broken (or using a weird dialect) because I initially tried putting the tests for the path separators/end of line outside the pattern group and it wasn't matching. Either that or I was still half asleep.

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    Re: Regex help please

    Here's another attempt that's a bit more concise (at the expense of some readability):

    Code:
    /(thumbnails?|derivatives?)(/|$)

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