以python为例：
$ whereis python
可以看到以下python信息：
python: /usr/bin/python /usr/bin/python3.8-config /usr/bin/python3.8 /usr/bin/python2.7 /usr/lib/python3.9 /usr/lib/python3.8 /usr/lib/python2.7 /etc/python3.8 /etc/python2.7 /usr/local/lib/python3.8 /usr/local/lib/python2.7 /usr/include/python3.8
```bash $ python -V
显示当前python的版本：
Python 2.7.18
执行以下命令切换到python3.8
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.8
参考链接：https://blog.csdn.net/u011762313/article/details/47324839
