How To Install Latest Python In Ubutnu 18.04 (Shell Commands & Docker/Dockerfile)

This simple copy paste tutorial will allow you to install any version of Python.
Install python 2, all the way up to python 3.9+

You can select any version from this list: https://www.python.org/ftp/python/

I highly recommend using pipenv instead of installing python locally on any OS:
Works on ANY Ubuntu 16, 17, 18, 19, 20+

Using pipenv (highly, highly recommended!)

sudo apt update -y
sudo apt install python pipenv git -y
git clone https://github.com/pyenv/pyenv.git ~/.pyenv
echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
export PYENV_ROOT="$HOME/.pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"

Now you can install any version of Python with pyenv and pipenv

pyenv install 3.9-dev
cd /home/my/project
pipenv --python 3.9
pipenv shell
# pipenv run pip install -r requirements.txt
# pipenv run python manage.py

Force Installing on Ubuntu

# choose your version
py_version=3.8.4
sudo apt update -y
sudo apt install build-essential gcc autoconf make automake \
    wget libssl-dev zlib1g-dev libncurses5-dev libncursesw5-dev libreadline-dev libsqlite3-dev \
    libgdbm-dev libdb5.3-dev libbz2-dev libexpat1-dev liblzma-dev libffi-dev uuid-dev -y
wget https://www.python.org/ftp/python/${py_version}/Python-${py_version}.tgz
tar xzf Python-${py_version}.tgz
cd Python-${py_version}
sudo ./configure --enable-optimizations
sudo make altinstall
export PATH=/opt/python-${py_version}/bin:$PATH
which python3.8
python3.8 --version

Looking for the CentOS version? See CentOS version.

Install Python 3.x in a Dockerfile

# choose your version
ENV py_version=3.8.4
WORKDIR /root/
RUN apt update -y 
RUN apt install build-essential gcc autoconf make automake \
    wget libssl-dev zlib1g-dev libncurses5-dev libncursesw5-dev libreadline-dev libsqlite3-dev \
    libgdbm-dev libdb5.3-dev libbz2-dev libexpat1-dev liblzma-dev libffi-dev uuid-dev -y
RUN wget https://www.python.org/ftp/python/${py_version}/Python-${py_version}.tgz
RUN tar xzf Python-${py_version}.tgz
WORKDIR Python-${py_version}
RUN ./configure --enable-optimizations
RUN make altinstall
RUN export PATH=/opt/python-${py_version}/bin:$PATH
RUN which python3.8
RUN python3.8 --version