PHP 5：move_uploaded_file返回FALSE

Question

我有这段代码：

$target_dir = "images/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);
// Check if file already exists
if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}

// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
    } else {
        echo "Sorry, there was an error uploading your file.";
    }
}

我选择print_r($_FILES);

Array ( [fileToUpload] => Array ( [name] => 008f7f52-9087-40a0-9ec7-557a632cd320.jpg [type] => image/jpeg [tmp_name] => /tmp/phpNgZGh2 [error] => 0 [size] => 22355 ) )  

我不确定，但我认为这不是将文件保存到images文件夹。 I searched for the error 0 and I got nothing。该文件夹具有rwxrwxrwx权限。可能有什么问题，我该如何解决这个问题，以及为什么我会这样做？