Install Python 3.12 on Ubuntu 20.04 (WSL) using pyenv

This guide provides a clean and safe method to install Python 3.12 on Ubuntu 20.04 running under WSL2, without touching the system Python.

Linux distros normally have a Python version tied to the distro and used for various admin scripts. You should not expect to follow the latest releases of Python. And don't try to force change it because you could break your OS. If you need newer Python versions for your work, install it in user space.

Linux 20.04 come with python 3.8 which not supported natively to latest version of python (ex. 3.12.x), so by using pyenv will help you install other version of python without touching OS system, and it won't break your system.

🧹 1. Cleanup old Python PPAs (optional but recommended)

If you've previously tried installing Python via the deadsnakes PPA, clean it up first:

sudo rm -f /etc/apt/sources.list.d/deadsnakes*
sudo rm -f /etc/apt/keyrings/deadsnakes.gpg
sudo apt-key del BA6932366A755776 2>/dev/null || true
sudo apt clean
sudo apt update

Confirm cleanup:

grep -r "deadsnakes" /etc/apt/sources.list.d /etc/apt/sources.list || echo "✅ No deadsnakes entries found."

🧩 2. Install build dependencies

These packages are required to compile Python from source:

sudo apt update
sudo apt install -y build-essential libssl-dev zlib1g-dev libbz2-dev      libreadline-dev libsqlite3-dev curl libncursesw5-dev xz-utils tk-dev      libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev git

⚙️ 3. Install pyenv

Run the official installer script:

curl https://pyenv.run | bash

This installs:

pyenv – version manager
pyenv-virtualenv – for managing environments
pyenv-update – for updating pyenv

🪄 4. Configure your shell

Add the following lines to the bottom of your ~/.bashrc (or ~/.zshrc if you use zsh):

export PATH="$HOME/.pyenv/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

Reload the shell:

source ~/.bashrc

🐍 5. Install Python 3.12

Check available versions:

pyenv install --list | grep " 3\.12"

Then install the latest patch release (example: 3.12.7):

pyenv install 3.12.7

This step compiles Python from source — it may take several minutes.

🌍 6. Set Python 3.12 as the global default

pyenv global 3.12.7

Verify:

python --version
# Expected: Python 3.12.7

🧰 7. (Optional) Create a virtual environment

pyenv virtualenv 3.12.7 myproject-env
pyenv activate myproject-env

Deactivate later with:

pyenv deactivate

✅ Summary

Task	Description
Safe installation	Does not modify system Python
Works in WSL2	Fully compatible
Easily switch versions	`pyenv global` or `pyenv shell`
Supports virtualenvs	Isolated environments per project

🔁 Updating pyenv and Python

pyenv update
pyenv install --list | grep 3\.12
pyenv install 3.12.x  # latest patch
pyenv global 3.12.x

Done! 🎉
You now have a clean Python 3.12 setup using pyenv on WSL2 Ubuntu 20.04.

4sskick/install_python312_pyenv_wsl.md