Install multiple versions of Python

Installing Multiple Versions of Python on Ubuntu

kprabhu

Estimated reading time: 2 minutes

Managing multiple versions of Python on your Ubuntu machine can be incredibly beneficial. Whether you’re a developer testing applications across different Python versions or transitioning from an older version to the latest, this guide will help you set up and manage multiple versions of Python using two methods: pyenv and update-alternatives.

Table of contents

Method 1: Using pyenv to manage multiple Python versions

I found pyenv to be one of the easiest ways to manage various versions of Python. Here’s a step-by-step guide:

Step 1: Install pyenv

First, we need to install the dependencies required for pyenv:

sudo apt update
sudo apt install -y make build-essential libssl-dev zlib1g-dev \
libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
libncurses5-dev libncursesw5-dev xz-utils tk-dev libffi-dev liblzma-dev \
python3-openssl git

Then, install pyenv:

curl https://pyenv.run | bash

Add pyenv to your shell:

echo 'export PATH="$HOME/.pyenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(pyenv init --path)"' >> ~/.bashrc
echo 'eval "$(pyenv init -)"' >> ~/.bashrc
echo 'eval "$(pyenv virtualenv-init -)"' >> ~/.bashrc
source ~/.bashrc

Step 2: Install Python Versions

With pyenv installed, you can now install multiple versions of Python:

pyenv install 3.9.1
pyenv install 3.8.6
pyenv install 2.7.18

You can list all available versions with the following command:

pyenv install --list

Step 3: Set Global and Local Versions

Set a global version to use:

pyenv global 3.9.1

Set a local version for a specific directory:

cd my_project 
pyenv local 3.8.6

Method 2: Using update-alternatives to manage multiple Python versions

The update-alternatives method provides a way to set different versions of Python and switch between them.

Step 1: Install Python Versions

First, install the desired Python versions using apt:

# Add the repo for downloading python 
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt update 
sudo apt install python3.8 
sudo apt install python3.9

Step 2: Configure update-alternatives

Add the installed versions to the update-alternatives system:

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.8 1 
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.9 2

Here, I have set the highest priority to python3.9, so the default executable will be python3.9.

Step 3: Switch Between Versions

To switch between different versions, use:

sudo update-alternatives --config python3

You’ll see a list of installed versions and can select the one you want to use.

Conclusion

By following these methods, you can efficiently manage multiple versions of Python on your Ubuntu machine. The pyenv method provides a flexible, user-friendly approach, while the update-alternatives method integrates more closely with the system’s package management.

By managing multiple versions of Python, you can quickly test and develop applications across different environments, ensuring compatibility and smooth transitions between versions.

Suggested reading

Related Posts