$url = "http://www.site.com/file.php";
$dest_file = "footercache.txt"; //be sure it is chmod-ed to 0666 !!

$pagesource = request_cache($url, $dest_file, 3600*24*7);
echo $pagesource;

function request_cache($url, $dest_file, $timeout=7200) {

    if(strlen($dest_file) > 100) $dest_file = substr($dest_file, 20, 60) . substr($dest_file, strlen($dest_file) - 4);//keep some chars and the probable extension

    if(!file_exists($dest_file) || filemtime($dest_file) < (time()-$timeout)) {

        $data = @file_get_contents($url);
        if ($data !== false) {

            $tmpf = tempnam("/tmp","YWS");
            $fp = @fopen($tmpf,"w");
            @fwrite($fp, $data);
            @fclose($fp);
            if(file_exists($dest_file)) @unlink($dest_file);
            rename($tmpf, $dest_file);

        }else{

            touch($dest_file);//update its date only

        }

    } else {

        $data = file_get_contents($dest_file);

    }
    return($data);

}

?>