Linux CentOS 7, how to set Python3.5.2 as default

Question

Is there a way to set the Python 3.5.2 as the default Python version on CentOS 7? currently, I have Python 2.7 installed as default and Python 3.5.2 installed separately.

I used the following commands

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

but after that yum gives the error.

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

is there something I'm missing here?

NOTE: its the similar but opposite question of Linux CentOS 7, how to set Python2.7 as default Python version?

Answer 1

As the question goes, Linux CentOS 7, how to set Python3.5.2 as default Python version?

Will like to complement @OldFart's answer( Unforunately, can't comment else I would have).

when using the install param with update-alternatives, you can set the priority in auto mode. Implicitly saying that the alternative with the highest priority will be the default alternative should no alternative have been set manually. using the above answer as an example,

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

will set the python2 alternative with a priority of 50, and

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

will set the python3.5 alternative with a priority of 60. and by default, the python 3.5 becomes the default python executable for the python command.

should you want to change your default python alternative,

update-alternatives --config python

Find this a better approach as i don't have to modify my path files.

Answer 2

If this

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

doesn't work (it should)

you could just add an alias into your /home/.bashrcwith this command:

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

and if this does not work either you should just use virtual env. Read this page to get started.

Answer 3

I would suggest using 'alternatives' instead. As super-user (root) run the following:

# 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

The last command will ask you to choose between both alternatives.

As always, well most of the time anyways, you can check out the manual (manpages) using this simple command

man alternatives

Cheers