What does "pip install" do?

[Fabien]

On 12.01.2015 23:46, Chris Angelico wrote:
> On Tue, Jan 13, 2015 at 9:35 AM, Fabien<fabien.maussion at gmail.com>  wrote:
>> >BUT I'm still asking myself: what does "pip install"*concretely*  do on my
>> >virtual environment?
> As far as I know, it's equivalent to three steps:
>
> 1) Download the appropriate version of a package (the latest, if you
> didn't say otherwise)
> 2) Extract that package
> 3) Run 'python setup.py'.
>
> What setup.py does is up to the package, but for a pure-Python package
> it should simply create something in site-packages. It might do a lot
> more, though - compiling C or Fortran code, for instance.

Thanks Chris. I should then rephrase my question to "what does python 
setup.pt do?" ;-). My point was also that I think that this information 
(mostly: what will change on my system or my virtual env when I install 
a python package?) could/should be provided in the mentioned resources:

"Python Packaging Authority" website 
(https://pip.pypa.io/en/latest/user_guide.html),
"python-packaging-user-guide" 
(http://python-packaging-user-guide.readthedocs.org/en/latest/installing.html) 

"Installing python packages" from the python docs 
(https://docs.python.org/3/installing/)

I've found a bit more about this ("How installation works") in the 
Python 3 doc which is now considered legacy and might therefore not be 
read:
https://docs.python.org/3.4/install/index.html#installing-python-modules-legacy-version

Fabien