#!/usr/bin/perl
use strict;
use diagnostics;
use warnings;

my $string = 'Hello sailor';
my $regex = 'Hello (.*)';
my $substitution = 'Goodbye \\1';

$string =~ s/$regex/$substitution/;
print "string is now $string \n";

# I wanted: 	string is now Goodbye sailor
# I got:  		string is now Goodbye \1