ubuntu更换python版本

1、首先查看系统中是否安装Python：

whereis python

如果已安装，将提示如下：

root@ubuntu:~# whereis python
python: /usr/bin/python /usr/bin/python2.7 /usr/bin/python3.5m /usr/bin/python3.5 /usr/bin/python2.7-config /usr/lib/python2.7 /usr/lib/python3.5 /etc/python /etc/python2.7/etc/python3.5 /usr/local/lib/python2.7 /usr/local/lib/python3.5 /usr/include/python2.7  /usr/share/python /usr/share/man/man1/python.1.gz

如果没安装，安装：sudo apt-get install python3

2、查看当前版本：python -V

3、切换版本：

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

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 150

如果要切换到python2，输入：

sudo update-alternatives --config python