ubuntu下同时存在Python2.7.6和Python3时更改优先级

Ubuntu自带一个Python2.7.6和python3.x

使用命令行输入Python2时自动默认Python2.7.6

想使用python3必须键入Python3。因此采用以下办法

sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 100
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 200

此时再次在终端键入Python

Python 3.4.3 (default, Oct 14 2015, 20:28:29)
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.