python 18.04LTS 更改默认python3.6

step 1:  add python 3.6 package, and then install it

 

sudo apt-get install software-properties-common

sudo add-apt-repository ppa:jonathonf/python-3.6
sudo apt-get update
sudo apt-get install python3.6

 

step 2:  change python2 to python3

cd /user/bin
rm python
ln -s python3.6m python

 during this process, if any error happen, please try:

cd /user/bin
sudo rm python
sudo ln -s python3.6m python