 for an application
to determine whether it was invoked using CGI or FastCGI is to call
<tt>getpeername(FCGI_LISTENSOCK_FILENO)</tt>, which returns
-1 with <tt>errno</tt> set to <tt>ENOTCONN</tt> for
a FastCGI application.<p>

The Web server's choice of reliable transport, Unix stream pipes
(<tt>AF_UNIX</tt>) or TCP/IP (<tt>AF_INET</tt>), is implicit in the
internal state of the <tt>FCGI_LISTENSOCK_FILENO</tt> socket.<p>


<h4><a name = "S2.3">2.3 Environment variables</a></h4>

The Web server may use envir