use strict;
my $str = 'matt,hardrock,victor,ben,hardrock,rocker,ranzian,hardrock,hardrock,victor,alpha,matt,hardrock-victor,ben,hardrock,rocker,ranzian,hardrock,matt,hardrock,victor,ben,hardrock,rocker,ranzian,hardrock,hardrock,victor,alpha,matt,hardrock-victor,ben,hardrock,rocker,ranzian,hardrock';
my $regex = qr/([\s\S].*?)((hardrock)[^-]|hardrock$)?/mp;
my $subst = '$2';
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