How can I determine a file's true extension/type programmatically?

Question

I am working on a script that will process user uploads to the server, and as an added layer of security I\'d like to know:

Is there a way to detect a file\'s true e

Answer 1

that could still be forged. I would ensure that you can not (or do not) run a file uploaded to the server automatically.

I would also have a virus/spy ware scanner, and let it do the work for you.