use strict;
my $str = 'https://www.facebook.com/v2.5/dialog/oauth?client_id=*****&state=*****&response_type=code&sdk=php-sdk-5.1.2&redirect_uri=http%3A%2F%2Flocalhost%3A8888%2Ffacebook%2Flink&scope=email%2Cuser_birthday%2Cuser_photos';
my $regex = qr/&redirect_uri=\S+?localhost\K%[^%]+/p;
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