bool virtual ( string $filename )
virtual() is an Apache-specific function which is similar to <!--#include virtual...--
> in mod_include. It performs an Apache sub-request. It is useful for including CGI scripts or .shtml files, or anything else that you would parse through Apache. Note that for a CGI script, the script must generate valid CGI headers. At the minimum that means it must generate a Content-Type header. To run the sub-request, all buffers are terminated and flushed to the browser, pending headers are sent too. This function is only supported when PHP is installed as an Apache module.
Performs the virtual command on success, or returns FALSE on failure.