How to Install Multiple Specific Versions of Python on MacOSX

Sometimes, you might need to use a Python package that requires a specific version of Python. For instance, you want to use a Python package that requires a specific version of Python.

There are a bunch of ways to do this.

How to Install Multiple Specific Versions of Python Using MacPorts

The first is using Macports as the package manager.

There are separate ports for several python versions 2.x and 3.x currently 2.4, 2.5, 2.6, 2.7 and 3.1, 3.2, 3.3 3.4 and 3.5.

For example, to install 3.4, do sudo port install python34

There is also a python_select port. Running it allows you to choose the Python version to run by /opt/bin/python.

E.g., to select MacPorts python 2.7 port select --set python python27

Note: each package manager needs to run as the only package manager. Otherwise, it will be confused with different versions of libraries and executables on its paths.

With homebrew, the short answer seems to be brew switch the equivalent to port_select.

How to Install Multiple Specific Versions of Python Using Pyenv

• Install pyenv using homebrew

  brew install pyenv
  

• Install the specific Python version, run:

  pyenv install <version>
  

• Select a python version:

  pyenv local 3.5.0
  

Note that you must update PATH to override the default Python version:

PATH="~/.pyenv/versions/3.5.0/bin:${PATH}"

To list available versions:

pyenv versions

You may have seen suggestions to use package managers like brew_python, pyenv, anaconda, or miniconda.

However, what if you want to install multiple Python versions with a symbolic link on MacOSX without a python package manager?

How to Install Multiple Specific Versions of Python Without a Package Manager

You can install this easily using homebrew on a MacOSX terminal.

• Install the required version:

   % brew install python@3.9
   % brew list | grep python
   % brew ls python@3.9
   % ls -l /usr/local/Cellar/python@3.9/3.9.10/bin/python3.9
  

• Add a soft link to /usr/local/bin/

   % ln -s /usr/local/Cellar/python@3.9/3.9.10/bin/python3.9 /usr/local/bin/python3.9
   % python3.9 -V
  

• Create a Python virtual environment

   % python3.9 -m venv venv
  

• Activate the virtual environment

   % source venv/bin/activate
  

• Deactivate the virtual environment

   % deactivate
  

And that’s it! Hack away.