macOS 借助homebrew 安装 Python3

brew install python3

 terminal反馈

==> python
Python has been installed as
  /usr/local/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /usr/local/opt/python/libexec/bin

If you need Homebrew's Python 2.7 run
  brew install python@2

You can install Python packages with
  pip3 install <package>
They will install into the site-package directory
  /usr/local/lib/python3.7/site-packages

See: https://docs.brew.sh/Homebrew-and-Python

可以看到python3的实际安装目录是/usr/local/bin/python3

4、打开配置文件并写入python的外部环境变量

open ~/.bash_profile