Code example of php readfile function downloading files and determining permissions

/**
* Application examples of header and readfile functions
* Download files and determine permissions
* edit bbs.it-home.org
*/
$file = get_file_address();// The real address of the file (supports url, but url is not recommended)

if (file_exists($file ))
{
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($ file));
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check= 0');
header('Pragma: public');
header('Content-Length: ' . filesize($file));
ob_clean(); //Pay attention to the call of this function, clear but not close the output cache , otherwise the first two characters of the downloaded file will be 0a
flush();
readfile($file); // Output file content
}
?>