Install multiple versions of Python

We will follow the procedure below to install a version of Python different than the system installed one.

In this system (WSL Debian 11), the distro provided Python is 3.9. We will install a newer release (3.12.3)

• Install required dependencies (follow the python dev guide docs)

# For debian 11, Add the following in /etc/apt/sources.lists:
# deb-src http://deb.debian.org/debian bullseye main

~ → sudo apt-get update 

~ → sudo apt-get build-dep python3 

~ → sudo apt-get install pkg-config 

~ → sudo apt-get install build-essential gdb lcov pkg-config \
    libbz2-dev libffi-dev libgdbm-dev libgdbm-compat-dev liblzma-dev \
    libncurses5-dev libreadline6-dev libsqlite3-dev libssl-dev \
    lzma lzma-dev tk-dev uuid-dev zlib1g-dev libmpdec-dev     

• Create a directory to hold the python installations (we will use ~/python. When completed this directory will contain a bin/ directory where the binaries can be found)

~ → mkdir -p ~/python

• Download the source code (in a different directory, here using ~/Download/) and untar:

Download → wget https://www.python.org/ftp/python/3.12.3/Python-3.12.3.tgz
Download → tar -zxvf Python-3.12.3.tgz

• In the directory with the untarred source code, run configure specifying the previously created directory as prefix, and compile:

Download → cd Python-3.12.3/

Python-3.12.3 →  ./configure --prefix=$HOME/python

Python-3.12.3 → make

• Install using make altinstall (NOT make install)

Python-3.12.3 → make altinstall

• The python binary should be now in $HOME:

Python-3.12.3 → cd ~

~ → ls $HOME/python/bin/
2to3-3.12  idle3.12  pip3.12  pydoc3.12  python3.12  python3.12-config

The new python can be used to create a new venv:

~ → ~/python/bin/python3.12 -m venv ~/venv/py3.12

~ → source ~/venv/py3.12/bin/activate

(py3.12) ~ → python --version
Python 3.12.3

Alternatives

• Use deadsnakes repository to install old python versions

• Use pyenv (a bit brittle?)

References

1. Python Developer’s Guide > Getting started > Setup and building > Install dependencies (devguide.python.org)
2. Using Python on Unix platforms > Python-related paths and files (docs.python.org)
3. cpython README.rst > Installing multiple versions (github.com/python)
4. pyenv/pyenv: Simple Python version management (github.com/pyenv)
5. Pyenv – lets you easily switch between multiple versions of Python | Hacker News (news.ycombinator.com)