Note that the final assertion has changed from (?! \( ) to (?! \]\( ).

my $text = "Hello, I am a [Perl Monk], still not good at [Regular Expr
+essions]. I have been helped immensely by the good monks at [Perl Mon
+ks](http://www.perlmonks.org). This is what I look like ![mymugshot].
+ Thank you.";

listlink($text);

sub listlink {
  my ($text) = @_;
 
  my @links = (
    $text =~ /
      (?<!\!\[) # make sure the match is not preceded by a ![
      (?<=\[)   # but is in fact preceded by just a [
      .*?       # the match
      (?=\])    # followed by a ]
      (?!\]\()  # but not followed by a (
    /xg
  );

  foreach my $link (@links) {
    print "$link\n";
  }
}

#######
Perl Monk
Regular Expressions
Perl Monks](http://www.perlmonks.org). This is what I look like ![mymu
+gshot
[download]

Update: took out superfluous code.

--

when small people start casting long shadows, it is time to go to bed

'twas the line breaks made the difference. The fix is to use [^\]]* for the match.

(. doesn't match new line characters unless you ask nicely with the /s switch.)

---

Perl is environmentally friendly - it saves trees