7 ton shark

Enabling Python on new Macs

I recently had to setup a new MacBook for work and almost immediately ran into an issue while installing NPM dependencies for a project. Sure enough, it was due to missing Python 2.7 in the base MacOS. (The most common culprit is node-sass, due to its widespread usage on older projects, but I'm sure there are others.)

Luckily there is a very easy fix for this: any NPM install dependency requiring Python nowadays should work fine on Python 3, so you can symlink python to python3 and avoid the hassle of installing Python 2.7 or equivalent. The only caveat here is that node-sass in particular uses env python, so it's important to symlink the right Python.

If you haven't already, install the Xcode Command-Line Tools, and then make sure Xcode's Python3 is installed:

xcode-select --install
ls $(xcode-select -p)/usr/bin/python3
# => /Library/Developer/CommandLineTools/usr/bin/python3

I like to create a generic folder, ~/bin, that I add to my PATH. I toss any miscellaneous scripts or tools that I use globally into this folder. (You can use any similar folder as long as it is part of your PATH.)

mkdir ~/bin
cd ~/bin
ln -s $(xcode-select -p)/usr/bin/python3 python
env python --version
# => Python 3.9.6

If you created this folder above, don't forget to add it the beginning of your path by adding the following to your ~/.zshrc:

export PATH=~/bin:$PATH

Reload your Terminal window and re-run your npm install command -- python post-install scripts should now work without issue.

The long term fix here is to eliminate reliance on Python 2.7. For example, in the case of node-sass, which is no longer in active development, you can replace it with the pure-javascript sass package. However, other libraries may have more complicated upgrade paths.