PHP function called on server shutdown?

Question

Is there anyway to register a PHP callback function to be executed when the HTTP server is shutdown?

Answer 1

No, because PHP would already have been shutdown since it is the server that loads it as a module.

Answer 2

No. It is not possible

Answer 3

There might exists some hooks that can be called on BeforeShutdown() but they depend on the HTTP server flavour and the callbacks may or not be appliable to PHP. This could be a question for serverFault.