ubuntu16下升级python3的版本

ubuntu16下升级python3的版本，这里是升级到3.8。

1.首先添加安装源，在命令行输入如下命令：
$ sudo add-apt-repository ppa:jonathonf/python-3.8

2.更新apt
$ sudo apt update

3.更新安装源后，通过apt安装Python3.8
$ sudo apt-get install python3.8

4.安装完成之后，设置Python3.8的优先级

$ sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 1
$ sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.8 2

update-alternatives命令可以修改系统默认命令的软链指向，

参考这里，上面两句指令就是修改了系统默认的/usr/bin/python3 的软链指向，指向了两个位置，最后面的1和2是优先级

这时安装完成，可以通过python3 -V查看版本

5.下一步，更新pip，如下
$ sudo apt install python3-pip
$ sudo pip3 install --upgrade pip

如果出现

Traceback (most recent call last):
File "/usr/bin/pip3", line 9, in <module>
from pip import main
File "/usr/lib/python3/dist-packages/pip/__init__.py", line 14, in <module>
from pip.utils import get_installed_distributions, get_prog
File "/usr/lib/python3/dist-packages/pip/utils/__init__.py", line 23, in <module>
from pip.locations import (
File "/usr/lib/python3/dist-packages/pip/locations.py", line 9, in <module>
from distutils import sysconfig

ImportError: cannot import name 'sysconfig' from 'distutils' (/usr/lib/python3.8/distutils/__init__.py)

解决方法：添加源

sudo vim /etc/apt/sources.list

添加以下

deb http://cn.archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ bionic-proposed main restricted universe multiverse

 保存退出后执行

sudo apt-get update

安装python3.8-distutils

sudo apt-get install python3.8-distutils

再重新执行安装pip

参考：

https://blog.csdn.net/mbdong/article/details/127662406

https://blog.csdn.net/qq_35505543/article/details/120345813