PHP Golf string inverter

convert.php

<?php

$strings = array(
	"\n"
);

if (!isset($argv[1]))
{
	die("Please specify an input file\n");
}

$file = $argv[1];
$newfile = preg_replace('/\.php/', '.inv.php', $file);
$input = @file_get_contents($file);
if (!$input)
{
	die("Could not open input file\n");
}

$output = $input;
foreach ($strings as $string)
{
	$find = "\"{$string}\"";
	$replace = "~" . ~$string;
	$output = str_replace($find, $replace, $output);

	$find = "'{$string}'";
	$replace = "~" . ~$string;
	$output = str_replace($find, $replace, $output);
}

file_put_contents($newfile, $output);
exit("Output saved to $newfile\n");