pyenv

I prefer using pyenv to manage multiple python installations. I good resource on pyenv is Real Python.

Integration with MacOS and Linux systems is supported by pyenv. To integrate with windows, which I have done, use pyenv-win. When I used pyenv-win, I installed by following the Github readme. I installed pyenv-win from a cloned pyenv-win repo.

pyenv install on Ubuntu

The versions of python are built from source. To build python, the following dependencies are recommended on pyenv's website:

sudo apt update

sudo apt install --no-install-recommends make build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev

To install pyenv, I use pyenv-installer. The following dependencies are needed to install pyenv, there is a lot, with almost total overlap with the python build dependencies:

sudo apt install -y 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 python-openssl git

After dependency installation, install pyenv with:

curl https://pyenv.run | bash

After installation, the following needs to be added to ~/.bashrc:

# Load pyenv automatically

export PATH="$HOME/.pyenv/bin:$PATH"

eval "$(pyenv init -)"

eval "$(pyenv virtualenv-init -)"

The shell needs to be restarted for path changes to take effect:

exec $SHELL

Install python versions with pyenv

To see a list of local python versions (* indicates active version, and may be empty with fresh install of pyenv):

pyenv versions

The system version is the python version that was installed by the OS.

There are a lot of python versions available. You can use grep to trim down the list, for example:

pyenv install --list | grep " 3\.[5]"

To install a python version (replace version as desired):

pyenv install 3.5.10

Activating python versions

You can set the global version with this command:

pyenv global 3.9.4

The global version is overridden by the local version (useful to run this command in the directory of the application):

pyenv local 3.8.9

And finally, you can override the local version in a shell with:

pyenv shell 3.8-dev

pyenv and virtual environments

The installer I used to install pyenv also installs pyenv-virtualenv. However, I don't use virtualenv and instead use venv.