Should i remove Python 3.6 while installing Python 3.8 or newer?

Question

I tried to install a certain python module that required python 3.6 minimum to work properly so I checked my version using python --version which gave me the output of Python 2.7.17 and then used python3 --version giving me Python 3.6.9. Now, I know for a fact that i have Python 3.8 installed because I ran apt install python3.8 just before checking the version.

If someone wants to know what my system is running; I am currently running Elementary OS 5.1.7 Hera.

EDIT: (IDK what term to use, I want to say I am done going through answers, and I liked none.) After a while of whacking my brain, I decided not to uninstall the 3.6 version as It may have version specific modules which if removed may cause other installed programs to break.
Since I just use Linux for my college-work, It wont matter if more than one versions are installed anyway.

Sorry for any mistakes I may have made, I was never good at this kind of things.

Answer 1

This question is more appropriate for Unix & Linux.

Python installations (more generally, versioned installations of software) co-exist on linux using version numbers. You can likely run Python 3.8 using the python3.8 command (or else, locate where you installed it and run from there / add the location to the PATH environment variable to run directly).

Likewise, for each python version you can install its own package manager (e.g. install pip3.8 by python3.8 -m pip install pip) and use it to install packages for that python version. (As different projects require different sets of packages, the general practice is to create a "virtual environment", i.e. a separate copy of the needed version of python, pip and their package installation folders for each project, and install the required packages there - for more information see e.g. this excellent answer).

Regarding the command python3 (usually /usr/bin/python3) is just a symbolic link, you can replace it with the version you like (as long as it remains compatible with what the system expects - i.e. python3 of version no less than your built-in python3/python3-minimal, otherwise you will probably break something), e.g. assuming which python3 gives you /usr/bin/python3, you can

sudo rm /usr/bin/python3 #remove existing link
sudo ln /usr/bin/python3.8 /usr/bin/python3 # create a new link to the version of your choice

(although a better alternative could be instead aliasing it alias python3='/usr/bin/python3.8' and adding this to ~/.bashrc).

Whatever you do, do not uninstall python3-minimal as it is - at least, on Ubuntu - required by the system and uninstalling or changing it will likely break the system.

Answer 2

Use conda to install and manage different versions of Python (or lots of other software, for that matter). Install different Python versions in separate conda environments. For example:

Find what python versions are available:

conda search python

Output (as of the time of writing, in the future I expect that the latest Python versions will be higher):

Loading channels: done
# Name                       Version           Build  Channel             
python                         1.0.1               0  conda-forge         
python                           1.2               0  conda-forge         
...
     
python                         3.9.0      h88f2d9e_1  pkgs/main           
python                         3.9.0 ha017127_4_cpython  conda-forge         

Install the Python versions you need in separate environments. Here, install Python 3.9.0 in environment named python39:

conda create --name python39 python=3.9.0

Switching environments is easy:

conda activate python39
# python is now 3.9.0
conda deactivate
# back to the default python

or (deprecated now):

source activate python39
source deactivate

SEE ALSO:

conda docs: Managing environments