How can I use Homebrew to install both Python 2 and 3 on Mac?

Question

I need to be able to switch back and forth between Python 2 and 3. How do I do that using Homebrew as I don\'t want to mess with path and get into trouble. Right now I have

Answer 1

There are ways to use both , but the simplest solution today is to use pyenv. pyenv allows easy switching between versions. Here is what I did to set up:

STEP1:

Remove all pythons from your mac

 brew uninstall --ignore-dependencies --force python
 sudo rm -rf ~/miniconda3/
 sudo rm -rf ~/.conda/

Remove the following from ~/.bash_profile

export PATH="/Users/ishandutta2007/miniconda3/bin:$PATH"

and also the following from ~/.bashrc

export PYTHONPATH=/usr/local/lib/python2.7/site-packages:$PYTHONPATH
export PYTHONPATH=/usr/local/lib/python2.7/site-packages/google:$PYTHONPATH
alias python="/usr/bin/python"

STEP2:

Install pyenv and the python versions you need

brew update
brew install pyenv
pyenv install 2.7
pyenv install 3.7.0

STEP3:

add pyenv init to bash_profile or bashrc

echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n  eval "$(pyenv init -)"\nfi' >> ~/.bash_profile

STEP4:

Check what got installed

pyenv versions

• system (set by /Users/ishandutta2007/.pyenv/version)

  2.7

  3.7.0

STEP5:

Choose a default

pyenv global 3.7.0

When a project needs older version, just go its root folder and run

pyenv local 2.7