php man page for umask

UMASK(3)								 1								  UMASK(3)

umask - Changes the current umask

SYNOPSIS
       int umask ([int	$mask])

DESCRIPTION
       umask(3)  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.

PARAMETERS
	      o $mask
		- The new umask.

RETURN VALUES
       umask(3) without arguments simply returns the current umask otherwise the old umask is returned.

EXAMPLES
       Example #1

	      umask(3) example

	      <?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');
	      }
	      ?>

NOTES
       Note

	       Avoid using this function in multithreaded webservers. It is better to change the file permissions with chmod(3) after creating the
	      file.  Using  umask(3) can lead to unexpected behavior of concurrently running scripts and the webserver itself because they all use
	      the same umask.

PHP Documentation Group 														  UMASK(3)