umask

umask() sets PHP's umask to mask & 0777 and returns the old umask. When PHP is being used as a server module, the umask is restored when each request is finished.

The new umask.

umask() without arguments simply returns the current umask otherwise the old umask is returned.

Avoid using this function in multithreaded webservers. It is better to change the file permissions with chmod() after creating the file. Using umask() can lead to unexpected behavior of concurrently running scripts and the webserver itself because they all use the same umask.

<?php
$old = umask(0);
chmod("/path/some_dir/some_file.txt", 0755);
umask($old);

// Checking
if ($old != umask()) {
    die('An error occurred while changing back the umask');
}
?>