Installing Python 2 on Mac OS X

Homebrew is a package manager for OS X. A package is a collection of code files that work together. Installing them usually means running a script (a bit of code) that puts certain files in the various directories. A lot of the packages you will want are going to have dependencies. That means they require you to have other packages already installed on your computer. Homebrew will find and install dependencies for you AND it will keep them organized in one location AND it can tell you when updates are available for them. On top of all of that it gives super helpful instructions when everything doesn't go smoothly. You can read more about it at Homebrew's website. For now, install Homebrew using the following line of code:

$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

The script will explain what changes it will make and prompt you before the installation begins. Once you’ve installed Homebrew, insert the Homebrew directory at the top of your PATH environment variable. You can do this by adding the following line at the bottom of your ~/.profile file

export PATH="/usr/local/bin:/usr/local/sbin:$PATH"

Now, we can install Python 2.7:

$ brew install python@2

Because python@2 is a “keg”, we need to update our PATH again, to point at our new installation:

export PATH="/usr/local/opt/python@2/libexec/bin:$PATH"

Homebrew names the executable python2 so that you can still run the system Python via the executable python.

$ python -V   # Homebrew installed Python 3 interpreter (if installed)




$ python2.7 -V  # Homebrew installed Python 2 interpreter




$ python3 -V  # Homebrew installed Python 3 interpreter (if installed)