Make new linux user accounts with pjp /mysql

Hi All I think this may be a bit of topic but here goes. I would like to know what logic is needed to create a new user on a Linux box Once this user has completed a sign up. I want to create my own php / mysql driven webhost control panel which allows Creation of vhost in http.conf Creation of user account Creation of a MySql db for that user Creation of pops for that users Just like some other Host CP's I have seen. Maybe store info in a db for users to be able to edit / add services. Any thoughts, examples, warnings, advice as always appreciated. This will be running on a LINUX box if that make a difference. Thank you in advance and again sorry if its slightly of topic. Dave C