use strict;
my $str = 'http://forums.scamadviser.com/site-feedback-issues-feature-requests/20/
https://forums.questionablecontent.net/index.php/board,1.50.html
https://forums.comodo.com/how-can-i-help-comodo-please-we-need-you-b39.30/';
my $regex = qr/\d+(?=\D*$)/mp;
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