$userfile_name The name of the uploaded document
$userfile_tmp_name The temporary name where the uploaded document is saved
$userfile_size The size of the uploaded document, in bytes
$ userfile_type The mime type of the uploaded document
The above variables in PHP file uploading are normal in the windows+apache environment, but if they are inaccessible under Linux, you can use the following variables
$_FILE['userfile']['name'] is equivalent to $userfile_name
$_FILE['userfile']['tmp_name'] is equivalent to $userfile_tmp_name
$_FILE['userfile']['size'] Equivalent to $userfile_size
$_FILE['userfile'][type] Equivalent to $userfile_type