how to add ftp users to an apache from PHP?

how do i go about adding ftp users to an apache web server? i need the user to register from normal web/script and then have an FTP account set up for them automatically.

I have seen the cPanel API, and it is pretty decent, but sin开发者_如何转开发ce cPanel costs money, i don't wish to use it for this project. I'm also reluctant to use any other lisenced piece of software.

i want to be able to do it using shell/batch (or pure PHP, though that hardly seem plausible)

Well as you said Apache is a Web and not an FTP Server. But most FTP servers like e.g. PureFtpd offer MySQL authentication. So you just have to modify the authentication table with PHP to add new users.