use strict;
my $str = 'Text outside any div
<div id="my_id"> bla bla
<div>
bla bla bla
<div style="some style here">
lalalalala
</div>
</div>
I\'m trapped in a div!
</div>
more text outside divs
<div>more divs here!
<div id="justbeingannoying">radiohead rules</div>
</div>';
my $regex = qr/<div\b[^<]*>(?:[^<]+(?:<(?!\/?div\b)[^<]*)*|(?R))*<\/div>\s*/ip;
my $subst = '';
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