1

I have a file with several different lines. I'm looking for lines that contain(more or less) pattern like this:

\[.*<.*>.*\]

In other words, I want the lines that have <something> between []. Examples might be:

Line with [ <matching>|<pattern>]
A line <that> does[not]<match>[]
But [this[<should>]be matched] too
[match [me] <buddy>]

The only characters allowed between <> are alphanumeric characters and underscore.

I've tried both regexp above and its lazy version, but it didn't seem to work. What is the proper regexp?

  • How about line [with <foo]bar> or line [with <foo]bar> baz] or a [b <c[d]e> f]? – Stéphane Chazelas Aug 27 '15 at 13:20
  • @StéphaneChazelas I've updated my question to answer yours. – MatthewRock Aug 27 '15 at 13:23
2

If your [, ] pairs are always matched and you don't criss-cross [...]s with <...>, and your grep supports the -P option (like GNU grep when built with PCRE support), you can do:

grep -P '>(?!((?:[^]]|\[(?1)\])*)$)'

That is, look for a > that is not followed by only matched [...] pairs. It uses PCREs' (?1) recursive matching mechanism.

  • Outstanding. Works like a charm. – MatthewRock Aug 27 '15 at 13:50
1

POSIXly, you could do it with sed:

sed  '
  h; # make a copy of the pristine line on the hold space
  :1
    /\[[^]]*<[^]]*>[^]]*]/{
      # found a [...<x>...]
      g; # retrieve our saved copy and branch off
      b
    }
    s/\[\([^]]*\)]/\1/g; # remove inner [...]s
    # and loop if that s command was successful
  t1
  # no [...] left to remove, discard this line.
  d'

That is, remove pairs of [...] starting from the inner ones until you find a <...> within a pair.

(on Solaris or very old systems, remove the comments as Solaris sed only allows comments at the start of the lines).

0

This pattern with lazy matching (needing -P AFAIU) works for me:

grep -P '\[[^\]]*?<.*>.*?\]'
0

I came up with the following solution:

grep -P '\[[^.\]]*<.*>[^.\[]*\]' filename

In other words we match a pair of [ and ] with a pair of < and > in between with the following constraints:

  1. between [] must not be closing and opening bracket accordingly before and after the <> pair "[^.\]]*".
  2. inside <> must be at least one character.

This solution is also much faster than the regex with lazy quantifiers.

  • Unfortunately fails for [a [b] <c>] – MatthewRock Aug 27 '15 at 13:12

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