Set or remove the read-only attribute assigned to files with PHP chmod

Chmod.php, change file attributes with PHP, to make files read only or normally accessible on Windows IIS servers. Sometimes you need chmod to make files read only on your website, or make them normally accessible in case they already are read only. For instance Drupal’s settings.php configuration file, or WordPress Contact Form 7 temporary captcha files, are examples of read-only files.

PHP chmod function to make files read only or normally accessible on Windows Server IIS

On Windows Server IIS web servers, the PHP chmod() function isn’t supported, because the Windows Server operating system doesn’t recognize chmod as a command. Except when changing file attributes.

Yes, you’ve read it correct; you can use PHP’s chmod() to change file attributes on Windows Server IIS web servers! For this to happen, files need to be writable for the user under which the website operates (IUSR on IIS).

Here is an example function to change file attributes with PHP. Save the code as chmod.php for example.

 * example PHP function to make files read only
 * or normally accessible. Don't copy/paste this 
 * into production due to unsecured $_GET!
 * Follow me on Twitter: @Jan_Reilink
 * Donate:

  /* leave empty */
  $action = '';
  $file = '';

  if ( isset( $_GET['action'] ) && isset( $_GET['file'] ) ) {
    $action = $_GET['action'];
    $file = $_GET['file'];

  switch($action) {
  case "remove_readonly":
    changepermission( $file, '0755' );
  case "add_readonly":
    changepermission( $file, '0600' );
  default:  // default action if no action is matched
    changepermission( $file, '0755' );

  function changepermission( $files, $values ) {
    chmod( $files, $values );
?>Code language: PHP (php)

As said, files need to be writable for PHP (e.g. the user under which the application pool runs) to be able to change file attributes.

Now call chmod.php?action=add_readonly&file=myfile.php to make a file read only or chmod.php?action=remove_readonly&file=myfile.php to remove the read only flag using chmod.

Jan Reilink

Hi, my name is Jan. I am not a hacker, coder, developer or guru. I am merely an application manager / systems administrator, doing my daily thing at Embrace - The Human Cloud. In the past I worked for clidn and Vevida. With over 20 years of experience, my specialties include Windows Server, IIS, Linux (CentOS, Debian), security, PHP, websites & optimization. I blog at