Answers for "set python3.7 as default ubuntu"

set python 3 as default ubuntu

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.4 1
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2

set python 3 as default ubuntu

sudo update-alternatives --config python

link python3 to python3.7

Damn, Python is used throughout much of Ubuntu for system scripts and software,
and software relies on having Python (and the commands to start Python)
in a certain spot. do back then.

rm /usr/bin/python3 
ln -s /usr/bin/python3.7 /usr/bin/python3 

# create alias in ~/.bash_aliases

alias python3='/usr/bin/python3.7' 
Scripts can then start with something like:

#!/usr/bin/env python3

set python3.7 as default ubuntu

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.7 1

set python 3 as default ubuntu

update-alternatives: error: no alternatives for python3