set python3 7 as default ubuntu

1sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.4 1
2sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2
3

1sudo update-alternatives --config python
2

1Damn, Python is used throughout much of Ubuntu for system scripts and software,
2and software relies on having Python (and the commands to start Python)
3in a certain spot. do back then.
4
5rm /usr/bin/python3 
6ln -s /usr/bin/python3.7 /usr/bin/python3 
7
8# create alias in ~/.bash_aliases
9
10alias python3='/usr/bin/python3.7' 
11Scripts can then start with something like:
12
13#!/usr/bin/env python3 

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

1update-alternatives: error: no alternatives for python3 
2