php curl 重定向有关问题

$url = "http://localhost/opms/WebContent/test_output.php";

$post_data = array (

    "foo" => "bar",

    "query" => "Nettuts",

    "action" => "Submit"

);

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, $url); 

curl_setopt($ch, CURLOPT_POST, true);

curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

curl_setopt($ch, CURLOPT_FOLLOWLOCATION ,true);

curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookie.txt');

curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);

curl_setopt($ch, CURLOPT_MAXREDIRS,10);

curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);

$output = curl_exec($ch);

curl_close($ch);