I'm new to regex and found a command on a regex tutorial/test site that will allow me to search for 3 consecutive consonants. The only problem is I can't figure out how to use it with grep. Would someone help me out? I'm trying to search a word list text file using:


1 Answer 1


The Regex pattern you have contains:

  • Non-capturing group, (?:)
  • Zero width negative lookahead, (?!)

which are only supported by grep with PCRE, Perl Compatible Regular Expression (-P)

So you need grep -P, and to capture only the matched portion, -o:

% grep -Po '(?:([bcdfghjklmnpqrstvwxzy])(?!.{1,2}\1)){3}' <<<'foobarspfb'
  • Thanks, will except answer when it allows in a few mins. Any chance you can tell me how to make it list the whole word if it finds the pattern instead of just the pattern?
    – Austin
    Oct 31, 2016 at 6:02
  • @Jake You want to match whole words only?
    – heemayl
    Oct 31, 2016 at 6:04
  • no I just want to list the words that contain 3 or more consonants in a row
    – Austin
    Oct 31, 2016 at 6:08
  • @Jake ummmm, sorry I don't understand. It would be better if you ask this as a new question with an input chunk and your desired output from that.
    – heemayl
    Oct 31, 2016 at 6:10
  • Sorry I'll try to re-explain. I have a list of words that is too big for me to manually look through. I want to print out to my terminal each word in the list that is spelled with 3 or more non-vowel characters in a row. For example: it should print 'angst' because that has 4 consonants in a row (ngst), but it shouldn't print 'paper' because that only has 1 consonant in a row.
    – Austin
    Oct 31, 2016 at 6:13

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