I need to direct multiple domains to a single set of (PHP) files. So I point a domain at my server, which then goes to a single index.php file. This index.php file then detects the domain accessing it and returns the appropriate content. I do not want to add domains or set-up sites manually though as this is for a content management service. So it should be a case of a user signing up and it immediately works without me having to manually do anything. The file set must also exist only once, so updates can easily be applied to everyone.
I am currently on shared hosting, but I believe I may need to move to a VPS (running Apache) to achieve this.
How do I go about doing this?
Thanks