Ubuntu16.04スイッチpythonバージョン

Python2.7とpython3.5はデフォルトでubuntu16.04にインストールされています

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

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切り替える方法は？

1. 現在は2.7です

hanli@ubuntu:/usr/bin$ python
Python2.7.12(default,Nov192016,06:48:10)

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2. 2つのコマンドを実行します

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

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3. もう一度確認してください3.5になっています

hanli@ubuntu:/usr/bin$ python
Python3.5.2(default,Nov172016,17:05:23)

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4. 自由に切り替える方法

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

# 番号の前*記号は現在のバージョンを示します。1を入力して2に切り替えます.7.次のように再度確認します

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: