Bash regex not capturing

Question

I have a string which includes the text:

...,"names":"exampleName",...

I have the following if statement that checks if the regex pattern matches the string:

if [[ $string =~ names\":\"(\w+)\" ]]; then
      echo "Matches"
fi

The problem is the echo statement never get's executed, which essentially means that the regex didn't match.

Is there something I'm doing wrong here? Because it should match...

Cheers.

$string is assigned the output of: string=$(curl ...) – Nick Mar 03 '13 at 21:57 — Nick, Mar 03 '13 at 21:57

score 1 · Answer 1 · edited May 23 '17 at 10:25

1

It's a quoting issue, see e.g this

Try:

$ string='...,"names":"exampleName",...'

$ re='names":"(\w+)"'

$ if [[ $string =~ $re ]]; then echo match; fi
match

edited May 23 '17 at 10:25

Community

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answered Mar 03 '13 at 22:18

Fredrik Pihl

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Escaped quotes don't trigger string matching. His problem is likely due to the `\w`. – chepner Mar 04 '13 at 13:42

score 1 · Answer 2 · answered Mar 03 '13 at 23:54

The problem here seems to be that you are using an unsupported character class identifier. As per reference 1 below, it appears that bash uses the POSIX character classes rather than the slash-escaped character classes used in vi and other places.

Rather than using \w you should use [[:alnum:]_] (alphanumerics plus the underscore). I'd say to use [[:word:]], but apparently not all versions of bash support that (as mine doesn't).

A version of your code modified appropriately would look like this:

string='...,"names":"exampleName",...'

if [[ $string =~ names\":\"([[:alnum:]_]+)\" ]]; then
  echo "Matches"
fi

References:

score 0 · Answer 3 · answered Mar 03 '13 at 23:22

0

Try:

if [[ $string =~ names\":\"[[:alnum:]_]+\" ]]; then

answered Mar 03 '13 at 23:22

Scrutinizer

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Bash regex not capturing

3 Answers3