[This post is about making changes in PHP's configuration files when you have full command-line access to the underlying Ubuntu 10 server. The commands should be identical for other Unix-based web servers.]
An important step in setting up hosting of any web site is tailoring PHP to the needs of the code you will be running. You do this by changing PHP's initialization files which have the extension .ini. There is at least one initialization file, called php.ini, and there may be others.