Setting Up pyenv in WSL (Ubuntu)

pyenv is a tool that allows you to manage multiple Python versions easily. This guide will walk you through setting up pyenv on WSL Ubuntu and installing Python 3.11.

Step 1: Update and Install Dependencies

Before installing pyenv, update your system and install necessary build dependencies.

sudo apt update && sudo apt upgrade -y
sudo apt install -y make 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

These dependencies are required for compiling Python versions.

Step 2: Install pyenv

Run the following command to install pyenv:

curl https://pyenv.run | bash

This script will:

• Clone pyenv into ~/.pyenv
• Add necessary paths to your shell configuration

Step 3: Configure Shell for pyenv

After installation, add the following lines to your shell configuration file.

For Bash (~/.bashrc)

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

Then apply the changes:

source ~/.bashrc

For Zsh (~/.zshrc)

If you are using Zsh, modify ~/.zshrc instead and run:

source ~/.zshrc

Step 4: Verify pyenv Installation

Check if pyenv is correctly installed by running:

pyenv --version

Expected output (version may vary):

pyenv 2.3.0

Step 5: Install Python 3.11 Using pyenv

To list all available Python versions installable using pyenv:

pyenv install --list

Once pyenv is set up, you can install Python 3.11.5 (or the latest available version) using:

pyenv install 3.11.5

or if you try to install the latest version:

pyenv install 3.11

Once installed, you can check the installed versions:

pyenv versions

Step 6: Set Python 3.11 as Default Version

To set Python 3.11.5 as the global default version:

pyenv global 3.11.5

To verify the installed Python version:

python --version

Expected output:

Python 3.11.5

To use a different Python version locally in a project directory:

pyenv local 3.11.5

If you want to switch between versions of python in a shell: Ensure that python version you specified is installed using pyenv install <version>

pyenv shell 3.11.5

How pyenv Internally Works

How pyenv Manages Python Versions

• When you install a Python version using pyenv install <version>, it:
  1. Downloads the Python source code from official sources.
  2. Compiles and installs Python into ~/.pyenv/versions/<version>/.
  3. Creates a shim directory at ~/.pyenv/shims/, which intercepts Python-related commands.
  4. Determines which Python version to use based on:
     • The local .python-version file (if present in the current directory)
     • The PYENV_VERSION environment variable (if set)
     • The globally set Python version (pyenv global <version>)

How pyenv Installs Python Packages

pyenv itself does not manage Python packages, but you can use package managers like pip inside a pyenv environment.

To install packages:

pip install <package>

• These packages will be installed in the respective Python version directory under ~/.pyenv/versions/<version>/lib/python3.x/site-packages/.
• If you’re using pyenv virtualenv, each virtual environment will have its own package directory.

How pyenv Overrides System Python

• pyenv modifies your shell’s PATH to prioritize its own versions of Python.
• When you run python, your shell looks in ~/.pyenv/shims/, which then directs to the correct Python binary.
• You can check which Python is currently being used with:

  which python
  

  Expected output:

  /home/user/.pyenv/shims/python
  

You’re All Set! 🎉

Now you have pyenv installed on WSL Ubuntu, and Python 3.11.5 is ready to use. 🚀