Linux: Install Python on Ubuntu

Note

There is no installer for Python on Linux, but the source code must be compiled locally. Python can also be installed via sudo apt-get python, but usually does not install the latest version.

Manual install from sources

  1. Run these commands to make sure, all packages required for building Python from sources is available on the local system:

    $ sudo apt-get update
$ sudo apt-get install build-essential
$ sudo apt-get install libncurses5-dev libncursesw5-dev libgdbm-dev libc6-dev
$ sudo apt-get install zlib1g-dev libsqlite3-dev tk-dev
$ sudo apt-get install libssl-dev openssl python-openssl
$ sudo apt-get install libffi-dev wget
$ sudo apt-get install libbz2-dev libreadline-dev llvm xz-utils liblzma-dev

  2. Open https://www.python.org, select Downloads / Source code and select Download XZ compressed source tarball of the version you like to install

    Hint

    Alternatively, you may download the file to the current directory via

    $ wget https://www.python.org/ftp/python/<version>/Python-<version>.tgz

    where <version> is the Python version, you want to install (e.g. 3.9.4)

  3. Extract the archive:

    $ tar xzf Python-<version>.tgz

  4. Create system dependent Makefile and other dependencies:

    $ cd Python-<version>
$ sudo ./configure --enable-optimizations

  5. After completion, run the installation (using alternative-installation to allow us install additional Python versions, as Ubuntu has a system default installed):

    $ sudo make altinstall

  6. Python binaries now reside in the /usr/local/bin/ directory, library files reside in /usr/local/lib/.

  7. Try, if the Python installation is referenced by the python3 command (it should have been set as default Python interpreter).

  8. Delete or archive downloaded archive and unzipped directory.

Uninstall a Python version

Prerequisites

  • Python has to be installed according to upper description

  • Python installation files reside on system (may need to re-download and configure)

Steps

  1. Navigate into the installation files directory (e.g. ~/Downloads/Python-<x.x.x>).

  2. Run

    $ sudo make uninstall

Install and manage multiple Python version

Installing various minor version (e.g. 3.6, 3.7, 3.8 and 3.9) in parallel is possible, but your python3 command will always refer to a particular Python version, likely the one you installed last.

The out-of-the-box solution is to use the version-specific executable like python3.9 for your Python 3.9 installation or python2.7 for the Python 2.7 installation.

Additionally, Ubuntu already has a version Python 2 and Python 3 preinstalled on its system by default, which are not responding to any python, python2``or ``python3 or even the more specific python<x.x> commands, once you installed your own versions.

Assigning multiple versions as alternatives for any of these commands and switch the installation to be used for it can be achieved by using the updates-alternatives command.

  1. Add the system installations as alternative (here: 3.8 and 2.7):

    $ sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.8 1
$ sudo update-alternatives --install /usr/bin/python2 python2 /usr/bin/python2.7 1

  2. Add the user installed installations as alternative (here: 2.7, 3.6, 3.7, 3.8 and 3.9):

    $ sudo update-alternatives --install /usr/local/bin/python2.7 python2 /usr/local/bin/python2.7 2
$ sudo update-alternatives --install /usr/local/bin/python3.6 python3 /usr/local/bin/python3.6 2
$ sudo update-alternatives --install /usr/local/bin/python3.7 python3 /usr/local/bin/python3.7 2
$ sudo update-alternatives --install /usr/local/bin/python3.8 python3 /usr/local/bin/python3.8 2
$ sudo update-alternatives --install /usr/local/bin/python3.9 python3 /usr/local/bin/python3.9 2

    Hint

    You may also define alternative for the general python command, by stating python instead of python3 in the above commands.