Update Python 3.5 to 3.6 via terminal

Using Ubuntu 17.04. After update Python 3.5 to 3.6 via terminal according to https://askubuntu.com/a/865569/695385 still showing that version is 3.5.3.

~$ python3 --version
Python 3.5.3

How is this installed?

I had the same problem, I did the following instruction to resolve it:

After installing Python3.6:

To make python3 use the new installed Python 3.6 instead of the default 3.5 release, run following 2 commands:

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 1

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 2

Finally, switch between the two Python versions for python3 via the following command:

sudo update-alternatives --config python3

Then select the /usr/bin/python3.6 -- automode in choices menu, for me that was 0 row.

[Result]:

$ python3 -V
Python 3.6.9

Or:

$ python3 --version
Python 3.6.9

How did you upgrade? I suspect you may have a python3.6 binary somewhere.

Generally speaking, you never want to replace /usr/bin/python or /usr/bin/python3 with your own fruity versions. Important parts of Ubuntu require their stable Python environments, and largely speaking, that is incompatible with you mucking around.

That all said, having a /usr/bin/python3.6 (or /usr/local/bin/python3.6, or whatever in your path) would be fine. If you don't want to type all that in each time, you might want to look at virtualenv and the various wrapper automation options for it. This has the additional bonus of not threatening your system's site_packages with your development work.

Installing and upgrading to Python3.6 requires the command

sudo apt-get upgrade python3.6

Use Docker and get the Python image for whatever version you want. It's also easy to update.

FROM python:3.6

RUN apt-get update \
    && apt-get install -y --no-install-recommends \
        postgresql-client \
    && rm -rf /var/lib/apt/lists/*

WORKDIR /usr/src/app
COPY requirements.txt ./
RUN pip install -r requirements.txt
COPY . .

EXPOSE 8000

This answer is not specific to python3.5 to python3.6 but can be used in general. Assuming the latest version of python to be python3.10

# Update apt repo
sudo apt update

# Install new python3.10
sudo apt install python3.10 python3.10-dev -y

# Unlink the python3 command
sudo unlink /usr/bin/python3

# Link to python3.10 binary
sudo ln -s /usr/bin/python3.10 /usr/bin/python3

# Checking python3 version
$ python3 --version
Python 3.10.0+

You might face some issue like this with your apt commands after installing the newer python version

ImportError: No module named apt_pkg

For this you can try below commands to update the socket file link

# Reinstall python3-apt to create python3.10 apt socket file
sudo apt-get install python3-apt --reinstall

# Link the apt_pkg.so file to python3.10 socket file
cd /usr/lib/python3/dist-packages
sudo ln -s apt_pkg.cpython-310-x86_64-linux-gnu.so apt_pkg.so