upgrading python 3.6 to 3.8 ubuntu code example

Example 1: downgrade python 3.8 to 3.7 ubuntu

sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt-get update
sudo apt-get install python3.7

Example 2: change python 3.5 to 3.6 ubuntu

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 1

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


sudo update-alternatives --config python3