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

my ($text, $search);

$text = "\\x1\\x2\\x3\\x4";
$search = qr/x2\\.+\\x4/;

print "\nUsing variable in regex: (qr)\n";
print "Before: text = $text\n";
$text =~ s/$search/new/;
print " After: text = $text\n";

__END__

Using variable in regex: (qr)
Before: text = \x1\x2\x3\x4
 After: text = \x1\new