use strict;
my $str = '//party[@id=\'party1:abc\']/abc:person[@id=\'Trader\']/trade/abc:personId[@personIdScheme=\'urn:xyz:person-id:PEOPLESOFT\']/text()';
my $regex = qr//(\w+[[/])/p;
my $subst = '/:\\1';
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