macbook上多版本python切换

macbook上默认安装了2.x版本的python&＃xff0c;如果有时候要使用2.x版本的python&＃xff0c;有时候想使用2.x版本的python&＃xff0c;怎么办&＃xff1f;

• 已经有了2.x的python&＃xff0c;此时再安装3.x的python&＃xff1a;

$ brew install python

如果没有报错&＃xff0c;则该步骤完成&＃xff0c;如果报一个警告Warning: python3-3.x.y already installed, it’s just not linked
解决方法&＃xff1a;
$ sudo ln -s /usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/bin/python3
/usr/local/bin/python3*

• 使用python2.x时&＃xff0c;在终端输入 python&＃xff0c;要使用python3时在终端输入python3即可。

$ python Python 2.7.10 (default, Oct 23 2015, 19:19:21) [GCC 4.2.1
Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin Type “help”,
“copyright”, “credits” or “license” for more information.

$ python3
Python 3.5.1 (default, Apr 18 2016, 11:46:32) [GCC 4.2.1
Compatible Apple LLVM 7.3.0 (clang-703.0.29)] on darwin Type “help”,
“copyright”, “credits” or “license” for more information. $

如果要在文件中指定使用python2或者python3&＃xff0c;则只需要在首行写上#/usr/bin/env python 或者/usr/bin/env python3即可