use strict;
my $str = '[[plain wikilinks]]
<e>[[</e>first tag]]
<e dsss>[[</e>meta on first tag]]
<e dsss>[[</e><div>first tag + meta + container</div>]]
<e dsss>[[</e><div>first tag + meta + container + third tag</div><div>]]</div>
<e dsss>[[</e>forgot a bracket
<e dsss>[[</e>bracket containers<e>]]</e>
all is well';
my $regex = qr/(?:(?:(?:<([^ ]+)(?:.*)>)\[\[(?:<\/\1>))|(?:\[\[))(?:(?:(?:<([^ ]+)(?:.*)>)(.+?)(?:<\/\2>))|(.+?))(?:(?:(?:<([^ ]+)(?:.*)>)\]\](?:<\/\5>))|(?:\]\]))/mp;
my $subst = '$3$4';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html