ubuntu16.04中默认已经安装了python2.7和python3.5
代码语言：text复制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- 1
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怎么切换？
1.现在是2.7
代码语言：ruby复制hanli@ubuntu:/usr/bin$ python
Python 2.7.12 (default, Nov 19 2016, 06:48:10) - 1
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2.执行两条命令
代码语言：ruby复制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- 1
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3.再次查看已经变成3.5了
代码语言：ruby复制hanli@ubuntu:/usr/bin$ python
Python 3.5.2 (default, Nov 17 2016, 17:05:23) - 1
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4.怎么随意切换
代码语言：text复制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:
