Instalar python3 en mac

instalar python con brew

brew install python

crear el alias

echo "alias python=/usr/local/bin/python3" >> ~/.bashrc

activar el alias

source ~/.bashrc.bashrc

ejecutar el comando

MacBook-de-victor:~ victor$ python

Python 3.7.7 (default, May 15 2020, 01:21:59) 

[Clang 8.0.0 (clang-800.0.42.1)] on darwin

Type "help", "copyright", "credits" or "license" for more information.

>>> quit()

El capitan OS X trae por defecto python 2.7, para ejecutar esa version

/usr/bin/python

crear el alias para pip

echo "alias pip=/usr/local/bin/pip3" >> ~/.bashrc

activar el alias

source ~/.bashrc.bashrc