macOS 安装 python3

1. macOS 安装brew

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

brew -v
Homebrew 1.6.9
Homebrew/homebrew-core (git revision afcb; last commit 2018-07-05)

2. brew 安装 python3 默认不会安装 pip3，还是官网下载安装包安装

• 通过python3 get-pip.py 安装pip3 ，会导致pip3和pip在同一目录

$ pip2 --version
pip 19.0.3 from /Library/Python/2.7/site-packages/pip (python 2.7)
$ pip3 --version
pip 19.0.3 from /Library/Python/2.7/site-packages/pip (python 2.7)

• brew 安装 python3

brew search python3
brew install python3

Error: An unexpected error occurred during the `brew link` step
The formula built, but is not symlinked into /usr/local
Permission denied @ dir_s_mkdir - /usr/local/Frameworks
Error: Permission denied @ dir_s_mkdir - /usr/local/Frameworks

• brew 卸载 python3

$ brew uninstall --force python3
Uninstalling python... (1,849 files, 24.3MB)
Error: Could not remove /usr/local/Cellar/python/3.7.3! Check its permissions.

$ cd /usr/local/Cellar/
$ sudo rm -rf python/

参考：

1. Homebrew官网安装教程
2. mac安装brew 软件包管理工具Homebrew
3. Homebrew帮助文档
4. 如何在MacOS下安装Python3