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

my $data = q{&"<>'`};

my @subst = (
    [q|&| => q|&amp;|],
    [q|"| => q|&quot;|],
    [q|<| => q|&lt;|],
    [q|>| => q|&gt;|],
    [q|'| => q|&'|],
    [q|`| => q|&`|],
);

$data =~ s/($subst[$_]->[0])/$subst[$_]->[1]/osg for 0 .. $#subst;

print $data, "\n";