by Guillermo Madero.
Yes, for each OS there seems to be a particular way of doing this. I'm not into Unix/Linux and I didn't get the "I've never seen that", so I'll provide some references regarding each case.
* downloadsome-extension.so; uncomment some-extension.so in file php.ini:
Install and enable APC on Ubuntu 12.04 LTS.
How to enable zip extension for PHP on Linux/Ubuntu (zip.so, php.ini).
* install some-extension.so; uncomment some-extension.so in file some-extension.ini: