Apache Cookbook, 2nd Edition

6.13. Accessing the Authenticated Username

Problem

You want to know the name of the user who has authenticated.

Solution

Some scripting modules, such as mod_php, provide a standard interface for accessing values set by the server. For instance, to obtain the username that was used to authenticate from within a PHP script, it would access a field in the $_SERVER superglobal array:

$auth_user = $_SERVER['REMOTE_USER'];

For a Perl or mod_perl script, use:

my $username = $ENV{REMOTE_USER};

In a Server-Side Include (SSI) directive, this may look like:

Hello, user <!--#echo var="REMOTE_USER" -->. Thanks for visiting.

Other scripting modules may provide specific means of accessing this information. For those that don’t, or for nonscript applications, use the appropriate means to consult the REMOTE_USER environment variable.

Discussion

When a user has authenticated, the environment variable REMOTE_USER is set to the name with which she authenticated. You can access this variable in CGI programs, SSI directives, PHP files, and a variety of other methods. The value also will appear in your access_log file.

Note that although it is the convention for an authentication module to set this variable, there are reportedly some third-party authentication modules that do not set it but provide other methods for accessing that information.

See Also

• Recipe 6.14