On Ubuntu, how do you install a newer version of python and keep the older python version?

Question

Background:

• I am using Ubuntu
• The newer python version is not in the apt-get repository (or synaptic)
• I plan on keeping the old version as the default python when you call "python" from the command line
• I plan on calling the new python using pythonX.X (X.X is the new version).

Given the background, how do you install a newer version of python and keep the older python version?

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I have downloaded from python.org the "install from source" *.tgz package. The readme is pretty simple and says "execute three commands: ./configure; make; make test; sudo make install;"

If I do the above commands, will the installation overwrite the old version of python I have (I definitely need the old version)?

Answer 1

When you install from source, by default, the installation goes in /usr/local -- the executable in particular becomes /usr/local/bin/pythonX.Y with a symlink to it that's named /usr/local/python. Ubuntu's own installation is in /usr/ (e.g., /usr/bin/python), so the new installation won't overwrite it. Take care that the PATH environment variable doesn't have /usr/local/bin before /usr/bin, or else simple mentions of python would execute the new one, not the old one.

Answer 2

I'm just going to assume that by "newer version" you mean "released version that is newer than the default version in Ubuntu". That means python 3.1, which is in the repositories.

sudo apt-get install python3

Different python versions in the Ubuntu repositories can coexist with one another just fine. If you're on a version of Ubuntu older than Lucid, you'll have to upgrade your OS or enable the universe repository in order for python3 to show up in your package manager.

If you mean python 2.7, you should be aware that it hasn't been released yet.