if ($hosts->{$ip}) {
  print STDERR "Line $l: Warning: duplicate IP entry $ip, the last one will be used\n";
  }

##</code><code>##

 
127.0.0.1 192.168.0.1

##</code><code>##

    unless (defined $content) {
        open my($fh), "<", "/etc/hosts"
            or return [500, "Can't read /etc/hosts: $!"];
        local $/;
        $content = <$fh>;
    }