mv /usr/bin/python /usr/bin/python-old
sudo ln -fs /usr/bin/python3 /usr/bin/python

-bash: /usr/bin/yum: /usr/bin/python: bad interpreter: No such file or directory

sudo ln -fs /usr/bin/python3 /usr/bin/python

alias python="/usr/bin/python3.5"

# start by registering python2 as an alternative
alternatives --install /usr/bin/python python /usr/bin/python2 50
# register python3.5 as an alternative
alternatives --install /usr/bin/python python /usr/bin/python3.5 60
# Select the python to use
alternatives --config python

man alternatives

update-alternatives --install /usr/bin/python python /usr/bin/python2 50

update-alternatives --install /usr/bin/python python /usr/bin/python3.5 60

update-alternatives --config python