cgi - Call PHP from virtual/custom "web server"

Question

Basically, I'm trying to figure out how PHP can be called from a "web server".

I've read the documentation, but it didn't help much.

As far as I can tell, there are three ways to invoke PHP:

• via command line (eg: php -f "/path/to/script.php")
• via CGI(??) / via FastCGI (???)
• via a web server (eg: Apache) module

So let's start with CGI. Maybe I'm just blind, but the spec doesn't mention how on Earth the web server passes data (headers & callbacks) to the thing implementing CGI. The situation is even worse with FastCGI.

Next up, we have server-specific modules, which, I don't even know what to search for since all leads end up nowhere.

Answer 1

Invoking a CGI script is pretty simple. PHP has a few peculiarities, but you basically only need to setup a list of environment variables, then call the PHP-CGI binary:

setenv GATEWAY_INTERFACE="CGI/1.1"
setenv SCRIPT_FILENAME=/path/to/script.php
setenv QUERY_STRING="id=123&name=title&parm=333"
setenv REQUEST_METHOD="GET"
...

exec /usr/bin/php-cgi

Most of them are boilerplate. SCRIPT_FILENAME is how you pass the actual php filename to the PHP interpreter, not as exec parameter. Crucial for PHP is also the non-standard variable REDIRECT_STATUS=200.

For a GET request you only need the environment variables. For a POST request, you simply pipe the HTTP request body as stdin to the executed php-cgi binary. The returned stdout is the CGI response consisting of an incomplete HTTP header, , and the page body.

(Just from memory. There maybe a few more gotchas.)