Change the default python to Python3.8 on Ubuntu 20.04 fresh install

2022-01-02 Ubuntu

Just realized there is a specific package to resolve.

When got the fresh installed Ubuntu Focal Fossa server edition, you can use python3 but the default python has not set yet.

ubuntu@prime:~$ python

Command 'python' not found, did you mean:

  command 'python3' from deb python3
  command 'python' from deb python-is-python3

ubuntu@prime:~$ python3
Python 3.8.10 (default, Nov 26 2021, 20:14:08)

Follow the official doc to update-alternatives then got this:

ubuntu@prime:~$ sudo update-alternatives --set python /usr/bin/python3.8

update-alternatives: error: no alternatives for python

There are two methods to resolve:

Method 1:

ubuntu@prime:~$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.8 1

ubuntu@prime:~$ sudo update-alternatives --config python
There is only one alternative in link group python (providing /usr/bin/python): /usr/bin/python3
Nothing to configure.

Method 2: use the python-is-python3 package

ubuntu@prime:~$ sudo apt install -y python-is-python3

ubuntu@prime:~$ python -V
Python 3.8.10

Enjoy!