use strict;
my $str = 'kol1,kol2,"kol3,kol3a",hhhh,"bb,bbb",kkff,ddd,"lll"
';
my $regex = qr/(,)(?=[^"]*"(?:[^"\r\n]*"[^"]*")*[^"\r\n]*$)/p;
my $subst = '{comma}';
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