[tlug] Running multiple web development environments on one machine

[Dave M G <martin@example.com>]

TLUG,

I hope this question is appropriate here. It combines enough of 
installation issues of PHP, MySQL, and Linux.

Please feel free to tell me to RTFM if you can direct me to exactly 
where in the FM I should R. This is one of those situations where I am 
so lost on some fundamentals that I am not even sure which questions to ask.

I am running Ubuntu Linux, version 6.06 (called "Dapper") at home where 
I run MySQL 4.1.15. As a web site developer, the sites I develop are 
hosted on various hosting services, each with a different version of 
MySQL. One is 3.2, one is 4.1, and another will soon be upgrading to 
5.0. They also have slightly different versions of PHP, I think. They're 
all 4 something, but might have slightly different global variable 
settings. They are all using the same version of Apache.

What I would like to do is simultaneously run different versions of 
MySQL/PHP on my home system so that I can simulate as closely as 
possible the web hosting conditions for each site I develop.

Installation of MySQL/PHP on my home system was handled automatically 
when I installed Ubuntu. So the particulars of where it is and how it is 
handled are opaque to me.

What particularly confuses me, and the issue I most need explained in 
simple terms, is to do with how the database gets called from within a 
PHP script. I simply run a command that says:
mysql_pconnect('localhost', 'user', 'password')

This indicates to me that the command to access the database looks on 
localhost, and from there automatically resolves to the MySQL server. So 
if there were more than one MySQL version running, how would I specify 
which one to use? And then, if I were to make such specifications, then 
wouldn't those specifications themselves break the usage of the scripts 
on the web hosting service?

Ditto for PHP.

But, before I even get to that point, how can I install the different 
versions? The only way I know to do this is to use the Ubuntu package 
installer, Synaptic, which seems to assume that I am upgrading or 
downgrading and therefor replacing the version I have.

Then, after that how would I be able to specify for each web site I am 
developing which version to use? It would be nice to be able to bundle 
installations of PHP/MySQL and anything else under one directory, or in 
some conceptual way, so that in my home environment I could make my web 
sites adhere to the system that matches their web hosting service.

Thank you for any advice.

--
Dave M G