apt-get install for different python versions

Question

I have ubuntu 10.04 with python2.6 by default. I have installed python2.7.

When I want to install python packages with

apt-get python-<package> 

it gets installed to python2.6. How can I make it to install the package to python2.7? Is there any option?

I have looked at this, but I could not find such directories in my OS. I have considered using easy_install-2.7, but not all packages are supported. For example python-torctl.

I am more interested in binding python2.7 with apt-get install.

Answer 1

Python has got its own package managing facilities, in parallel to the one sets by the Linux distributions (including Ubuntu). The repository is the Pypi - Python Package Index, and packages are installed with pip or the easy_install script, which is part of Python's setuptools package.

As a rule of thumb, you should not use both the packages installed via pip/setuptools, and packages available to your distro (via apt-get, yum, urpmi, etc...) as they might conflict.

So, one of the less error prone way to deal with it is to have separate Python installs in your system - leave the python that came with the system for system scripts and such - on this python, make use of packages installed by your package manager only. And install other versions of Python (or even the same), to be run with "virtualenv"s - on these other install you install things with pip/setuptools only.

(And even if one opt to live boldly and not use virtualenvs, installing another python version on the same prefix (/usr, and even /usr/local) than your system's Python is a source to confusing errors and conflicts).

Note that the Debian - and Ubuntu - systems devised a way to run parallel official Python's in /usr, and to have apt-get to install Python packages to both Python versions at once. This mostly works, but they mess with Python's default directory hierarchy, and some applications fail to use Python in this way. (It is also a mess to find the module files themselves in a Debian or Ubuntu). So the above method apply as a recommendation even if your system do have more than one version of Python available on apt-get.

In short, once you have compiled your desired version of Python, do this:

1. use your system's package manager to install "python-setuptools" and "python-virtualenv" (not sure if these are the actual package names).
2. Use virtualenv to create an environment from which you will use your different Python version
3. Activate your virtualenv, and install Python packages using pip on it.

Virtualenv does feature a "--help" switch to help you, but you basically do:

$ virtualenv -p <path-to-python-interpreter>  <environment-dir>
$ source <environment-dir>/bin/activate

And there you are - all things using Python will "see" the interpreter in the virtualenv, due to environment variables set.