Ignore the top link on Google which takes you a process of using pyenv. It’s not until you’ve spent several hours painstakingly following the instructions that you find out it’s for some shell I’ve never used called Fish.

Just do:

1. brew install python2
2. brew install python3
3. then to use Python 2, use python2 and for Python 3, use python3

 

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i.e. DON’T DO:

1. use pyenv
2. make sure brew is up to date: brew update && brew upgrade pyenv
3. pyenv install 3.7.2
4. pyenv install 2.7.14
5. Set the global version with pyenv global 3.7.2
6. Set local versions (e.g. for legacy projects) with pyenv local 2.7.14

 

Notes:

• latest version of Python: https://www.python.org/downloads/
• Blog post on pyenv: https://weknowinc.com/blog/running-multiple-python-versions-mac-osx

 

Problems:

ERROR: The Python zlib extension was not compiled. Missing the zlib?

brew install readline xz

did not work for me.

This worked though:

CFLAGS="-I$(xcrun --show-sdk-path)/usr/include" pyenv install -v 2.7.14

 

More:

https://github.com/pyenv/pyenv/wiki/common-build-problems