virtual() is an Apache-specific
function which is equivalent 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. For PHP files, you need to use include()
or
require(); virtual() cannot
be used to include a document which is itself a PHP file.
To run the sub-request, all buffers are terminated and
flushed to the browser, pending headers are sent too.