How do I install pip for python 3.8 on Ubuntu without changing any defaults?

Question

I\'m trying to install pip for Python 3.8 on an Ubuntu 18.04 LTS.

I know this has been asked way too many tim

Answer 1

While we can use pip directly as a Python module (the recommended way):

python -m pip --version

This is how I installed it (so it can be called directly):
Firstly, make sure that command pip is available and it isn't being used by pip for Python 2.7

sudo apt remove python-pip

Now if you write pip in the Terminal, you'll get that nothing is installed there:

pip --version

Output:

Command 'pip' not found, but can be installed with:

sudo apt install python-pip

Install python3.8 and setup up correct version on python command using update-alternatives (as done in the question).

Make sure, you have python3-pip installed:
(This won't work without python3-pip. Although this will install pip 9.0.1 from python 3.6, we'll need it.)

sudo apt install python3-pip

This will install pip 9.0.1 as pip3:

pip3 --version

Output:

pip 9.0.1 from /usr/lib/python3/dist-packages (python 3.6)

Now, to install pip for Python 3.8, I used pip by calling it as a python module (ironic!):

python -m pip install pip

Output:

Collecting pip
  Downloading https://files.pythonhosted.org/packages/36/74/38c2410d688ac7b48afa07d413674afc1f903c1c1f854de51dc8eb2367a5/pip-20.2-py2.py3-none-any.whl (1.5MB)
  100% |████████████████████████████████| 1.5MB 288kB/s
Installing collected packages: pip
Successfully installed pip-20.2

It looks like, when I called pip (which was installed for Python 3.6, BTW) as a module of Python 3.8, and installed pip, it actually worked.

Now, make sure your ~/.local/bin directory is set in PATH environment variable:
Open ~/.bashrc using your favourite editor (if you're using zsh, replace .bashrc with .zshrc)

nano ~/.bashrc

And paste the following at the end of the file

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/.local/bin" ] ; then
    PATH="$HOME/.local/bin:$PATH"
fi

Finally, source your .bashrc (or restart the Terminal window):

source ~/.bashrc

Now if you try running pip directly it'll give you the correct version:

pip --version

Output:

pip 20.2 from /home/qumber/.local/lib/python3.8/site-packages/pip (python 3.8)

Sweet!