Using Pyenv to Manage Different Python Versions

Table of contents

The versioning problem

When working with different projects it is common to have different versions of the same programming language and dependencies for each one of them, so if we had a single installation or global version, this could give constant conflict between different projects.

To fix that we can use tools like pyenv and virtual environments. What these tools do is to isolate different versions of python and different installations (environments) of each of these versions.

Pyenv allows us to have different versions globally, locally, or even for the current shell.

Installing Pyenv

To learn more about the installation process we can follow the instructions in its repository.

In general, we can use its installation script:

curl https://pyenv.run | bash

Configure shell environment for Pyenv

After installation there is an additional step that is supposed to be done automatically, but in my case I have found that sometimes I have to do it mannually. It is really simple: when it is done installing, you have to configure it for the SHELL you are using.

For ZSH, just type each one of these lines (or manually add the quotes inside your ~/.zshrc):

echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.zshrc

echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.zshrc

echo 'eval "$(pyenv init -)"' >> ~/.zshrc

You can see the configuration for the other shells in the README of its own repository. And don’t forget to close and open the terminal to reload the configuration file or update it with source!

Common Pyenv Uses

We can see all available commands with pyenv --help or pyenv.

• See the available versions to install:

# list all versions
pyenv install -l

# filter versions containing 3.10
pyenv install -l | grep "3.10"

• Download and install a specific version:

pyenv install 3.10.13

• Select a version as global, local directory (perfect for when working with microservices with different versions), or for the current shell:

# select globally for your user account
pyenv global <version>

# automatically select whenever you are in the current directory (or its subdirectories)
pyenv local <version>

# select just for current shell session
pyenv shell <version>

Aditionally, to check the version of Python being used and the location:

pyenv version

which python