PHP umask() Function

The PHP umask() function changes permissions for files. It 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.

Syntax

umask(mask)

Parameters

mask

Optional. Specify the new umask. Default is 0777. The parameter consists of four numbers:

The first number is always zero (octal value)
The second number specifies permissions for the OWNER
The third number specifies permissions for the OWNER's USER GROUP
The fourth number specifies permissions for EVERYBODY ELSE

Possible values (to set multiple permissions, add up the following numbers):

1 = execute permissions
2 = write permissions
4 = read permissions

Return Value

Returns current umask if the function is called without arguments, otherwise the old umask is returned.

Example: umask() example

Lets assume that we have a file called test.txt in the current directory. In the example below, the umask() function is used to change the permissions for this file.

<?php
$old = umask(0);

//changing access
chmod("test.txt", 0755);

umask($old);

if ($old != umask()) {
  die('An error occurred while changing back the umask');
} else {
  echo "umask is changed back successfully.";
}
?>

The output of the above code will be:

umask is changed back successfully.

❮ PHP Filesystem Reference