1.  安装pip

sudo apt install python-pip

2. 检查pip 版本

pip --version 

发现pip版本是18.x的，过于旧，所以继续更新pip

3. 下载pip源码

https://pypi.org/project/pip/#files

4. 解压后进入目录，并开始build和安装

cd pip-20.3.1
sudo python setup.py build
sudo python setup.py install

 

5. 发现没有pip3,继续安装pip3

sudo python3 setup.py build 此时提示

Traceback (most recent call last):
  File "setup.py", line 8, in <module>
    from setuptools import find_packages, setup
ModuleNotFoundError: No module named 'setuptools'

6. 重新下载setuptool源码，给python3安装

https://pypi.org/project/setuptools/#files

cd setuptools-50.3.2
sudo python3 setup.py build
sudo python3 setup.py install

7. 返回头重新去安装pip3

cd pip-20.3.1
sudo python3 setup.py build
sudo python3 setup.py install