Ubuntu 安装python3及多版本切换详解编程语言

2.使用 update-alternatives 来为整个系统更改Python 版本

查看python替代版本信息

~$ update-alternatives --display python

但是结果为

update-alternatives: error: no alternatives for python

python的替代版本尚未被update-alternatives

查看python的位置

$ whereis python 

python: /usr/bin/python2.7 /usr/bin/python3.7 /usr/bin/python3.5m /usr/bin/python3.7m /usr/bin/python3.5 /usr/bin/python /usr/lib/python2.7 /usr/lib/python3.7 /usr/lib/python3.5 /etc/python2.7 /etc/python3.7 /etc/python3.5 /etc/python /usr/local/lib/python2.7 /usr/local/lib/python3.7 /usr/local/lib/python3.5 /usr/share/python /usr/share/man/man1/python.1.gz

更新一下替代列表

$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1 

update-alternatives: using /usr/bin/python2.7 to provide /usr/bin/python (python) in auto mode 

[email protected]:~$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.7 2 

update-alternatives: using /usr/bin/python3.7 to provide /usr/bin/python (python) in auto mode

查看python替代版本信息

$ update-alternatives --display python python - auto mode 

 link best version is /usr/bin/python3.7 

 link currently points to /usr/bin/python3.7 

 link python is /usr/bin/python 

/usr/bin/python2.7 - priority 1 

/usr/bin/python3.7 - priority 2

查看python版本

$ python -V 

Python 3.7.9

3.切换版本

切换到2.7

$ sudo update-alternatives --config python 

There are 2 choices for the alternative python (providing /usr/bin/python). 

 Selection Path Priority Status 

------------------------------------------------------------ 

* 0 /usr/bin/python3.7 2 auto mode 

 1 /usr/bin/python2.7 1 manual mode 

 2 /usr/bin/python3.7 2 manual mode 

Press enter to keep the current choice[*], or type selection number: 1 

update-alternatives: using /usr/bin/python2.7 to provide /usr/bin/python (python) in manual mode 

[email protected]:~$ python -V 

Python 2.7.12

pip版本

$ pip -V 

pip 8.1.1 from /usr/lib/python2.7/dist-packages (python 2.7)

切换到3.7

sudo update-alternatives --config python 

There are 2 choices for the alternative python (providing /usr/bin/python). 

 Selection Path Priority Status 

------------------------------------------------------------ 

 0 /usr/bin/python3.7 2 auto mode 

* 1 /usr/bin/python2.7 1 manual mode 

 2 /usr/bin/python3.7 2 manual mode 

Press enter to keep the current choice[*], or type selection number: 2 

update-alternatives: using /usr/bin/python3.7 to provide /usr/bin/python (python) in manual mode 

[email protected]:~$ python -V 

Python 3.7.9

安装pip

sudo apt install python3-pip

pip版本

 pip -V 

pip 8.1.1 from /usr/lib/python3/dist-packages (python 3.7)

pip的版本随着python版本切换

原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/20446.html