There is a little ftok function. This function isn't included into php for windows so i've grabbed it directly from linux glibc 2.3.2 source code. I hope that this can be useful.
There is the code:

<?php
function ftok($pathname, $proj_id) {
    $st = @stat($pathname);
    if (!$st) {
        return -1;
    }
    
    $key = sprintf("%u", (($st['ino'] & 0xffff) | (($st['dev'] & 0xff) << 16) | (($proj_id & 0xff) << 24)));
    return $key;
}

echo ftok($_SERVER["SCRIPT_FILENAME"], 250);
?>

sorry for my english :)