How can I change the default python on my Ubuntu 20.04 to Python3.8?

I would like to set python 3.8 as default on my PC Thinkpad X230 Ubuntu 20.04

I tried setting an alias

gt@gt-ThinkPad-X230:~$ alias python='usr/bin/python3.8'

Q: Does this alter a .bashrc file? If so, which? ~/.bashrc? another? if so, which?

gt@gt-ThinkPad-X230:~$ python --version
bash: usr/bin/python3.8: No such file or directory

Complains it cannot find /usr/bin/python3.8, buuuuut:

gt@gt-ThinkPad-X230:~$ ls /usr/bin/python*

/usr/bin/python /usr/bin/python3.8 /usr/bin/python3-pasteurize/usr/bin/python2 /usr/bin/python3.8-config /usr/bin/python3-unidiff/usr/bin/python2.7 /usr/bin/python3-config/usr/bin/python3 /usr/bin/python3-futurize

How do I get bash to find see /usr/bin/python3.8?

4 Answers

The correct way is sudo apt install python-is-python3 - it effectively does a symlink, but it also keeps pace with future updates; so if your ubuntu distribution moves to say Python 3.9, the manual symlink will no longer work, but the package makes sure it is still valid.

3

Firstly to answer your question, your approach should work, I think the path you've given in your alias needs the / preceding the path so the command should be alias python='/usr/bin/python3.8', this would indeed need to go into your ~/.bashrc file assuming you are using bash.

Secondly, Ubuntu has a really nice method of setting default binaries globally rather than messing with dot config files as depicted here: update-alternatives

a better solution may be to simply run:

sudo update-alternatives --set python /usr/bin/python3.8

This will ensure you have the version of python in use that you intend, everywhere.

5

You should be able to do it in a command shell by typing:

alias python=python3.8

To make it permanent you need to open up ~/.bashrc and add that line to the end of it. Should be as simple as that! Keep in mind this only works on a per user basis, which may or may not be what you want.

The other other thing that I notice with your attempt, is that your missing the leading /, so it should be reading as:

alias python='/usr/bin/python3.8'

without that leading forward / it may be trying to use a relative path.

1

Check the installed versions of Python:

ls /usr/bin/python*

Then, create the alternatives:

sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 1
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 2

Then, choose the version you want:

sudo update-alternatives --config python

You can easily switch between default Python versions.

1

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