Python安装3.7，切换Mac默认版本

安装过程homebrew install python3

本文主要介绍2.7切换到3.7。

如果没安装3.7，终端显示为：

technology-fly:~ lcm$ python3
-bash: python3: command not found

安装后显示为：

technology-fly:~ lcm$ python3
Python 3.7.2 (default, Jan 13 2019, 12:50:15) 
[Clang 10.0.0 (clang-1000.11.45.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 

原理：修改两个环境变量

1,终端输入 open ~/.bash_profile

添加以下代码

# Setting PATH for Python 2.7
PATH="/System/Library/Frameworks/Python.framework/Versions/2.7/bin:${PATH}"
export PATH
# Setting PATH for Python 3.7.2
PATH="/usr/local/Cellar/python/3.7.2/bin:${PATH}"

保存信息，终端输入source ~/.bash_profile

2,终端输入 open ~/.bashrc

添加以下代码

alias python2='/System/Library/Frameworks/Python.framework/Versions/2.7/bin/python2.7'
alias python3='/usr/local/bin/python3'
# alias python=python3

保存信息，终端输入source ~/.bashrc

即可