Webmaster in a Nutshell, Third Edition

Name

allow

Synopsis

                     allow 
                     from 
                     env
                     =variable
                  

[Within <Directory> or .htaccess]

The allow from env directive sets whether access to a directory should be granted if a specific environment variable exists. For example, the following grants access to the secret directory if the client is using Version 5.0 of the “InternetStar” browser, via a user-agent string:

BrowserMatch ^InternetStar/5.0 ACCESS_GRANTED
<Directory /secret>
order deny, allow
deny from all
allow from env=ACCESS_GRANTED
</Directory>