ubuntu16.04同时使用 pyhton2.7和3.5，并随意切换

ubuntu16.04中默认已经安装了python2.7和python3.5

hanli@ubuntu:/usr/bin$ ls |grep python
dh_python2
dh_python3
python
python2
python2.7
python2.7-config
python2-config
python3
python3.5
python3.5m
python3m
python-config
x86_64-linux-gnu-python2.7-config
x86_64-linux-gnu-python-config

怎么切换？

1.现在是2.7

hanli@ubuntu:/usr/bin$ python
Python 2.7.12 (default, Nov 19 2016, 06:48:10) 

2.执行两条命令

hanli@ubuntu:/usr/bin$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 100
update-alternatives: using /usr/bin/python2 to provide /usr/bin/python (python) in auto mode
hanli@ubuntu:/usr/bin$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 150
update-alternatives: using /usr/bin/python3 to provide /usr/bin/python (python) in auto mode

3.再次查看已经变成3.5了

hanli@ubuntu:/usr/bin$ python
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 

4.怎么随意切换

hanli@ubuntu:/usr/bin$ sudo update-alternatives --config python
There are 2 choices for the alternative python (providing /usr/bin/python).

  Selection    Path              Priority   Status
------------------------------------------------------------
* 0            /usr/bin/python3   150       auto mode
  1            /usr/bin/python2   100       manual mode
  2            /usr/bin/python3   150       manual mode

Press <enter> to keep the current choice[*], or type selection number: 1
update-alternatives: using /usr/bin/python2 to provide /usr/bin/python (python) in manual mode

#数字前面有*号表示是当前使用版本，输入1切换到2.7，再次查看如下

hanli@ubuntu:/usr/bin$ sudo update-alternatives --config python
There are 2 choices for the alternative python (providing /usr/bin/python).

  Selection    Path              Priority   Status
------------------------------------------------------------
  0            /usr/bin/python3   150       auto mode
* 1            /usr/bin/python2   100       manual mode
  2            /usr/bin/python3   150       manual mode

Press <enter> to keep the current choice[*], or type selection number: