Multiple Python versions on the same machine

Question

Is there official documentation on the Python website somewhere  on how to install and run multiple versions of Python on the same machine on Linux   I can find gazillions of blog posts and answers  but I want to know if there is a  standard  official way of doing this   Or is this all dependent on OS

User · Answer

Package Managers - user-level

For a package manager that can install and manage multiple versions of python, these are good choices:

pyenv - only able to install and manage versions of python
asdf - able to install and manage many different languages

The advantages to these package managers is that it may be easier to set them up and install multiple versions of python with them than it is to install python from source. They also provide commands for easily changing the available python version(s) using shims and setting the python version per-directory.

This disadvantage is that, by default, they are installed at the user-level (inside your home directory) and require a little bit of user-level configuration - you'll need to edit your ~/.profile and ~/.bashrc or similar files. This means that it is not easy to use them to install multiple python versions globally for all users. In order to do this, you can install from source alongside the OS's existing python version.

Installation from source - system-wide

You'll need root privileges for this method.

See the official python documentation for building from source for additional considerations and options.

/usr/local is the designated location for a system administrator to install shared (system-wide) software, so it's subdirectories are a good place to download the python source and install. See section 4.9 of the Linux Foundation's File Hierarchy Standard.

Install any build dependencies. On Debian-based systems, use:

apt update
apt install build-essential zlib1g-dev libncurses5-dev libgdbm-dev libnss3-dev libssl-dev libsqlite3-dev libreadline-dev libffi-dev libbz2-dev

Choose which python version you want to install. See the Python Source Releases page for a listing.

Download and unzip file in /usr/local/src, replacing X.X.X below with the python version (i.e. 3.8.2).

cd /usr/local/src
wget https://www.python.org/ftp/python/X.X.X/Python-X.X.X.tgz
tar vzxf Python-X.X.X.tgz

Before building and installing, set the CFLAGS environment variable with C compiler flags necessary (see GNU's make documentation). This is usually not necessary for general use, but if, for example, you were going to create a uWSGI plugin with this python version, you might want to set the flags, -fPIC, with the following:

export CFLAGS='-fPIC'

Change the working directory to the unzipped python source directory, and configure the build. You'll probably want to use the --enable-optimizations option on the ./configure command for profile guided optimization. Use --prefix=/usr/local to install to the proper subdirectories (/usr/local/bin, /usr/local/lib, etc.).

cd Python-X.X.X
./configure --enable-optimizations --prefix=/usr/local

Build the project with make and install with make altinstall to avoid overriding any files when installing multiple versions. See the warning on this page of the python build documentation.

make -j 4
make altinstall

Then you should be able to run your new python and pip versions with pythonX.X and pipX.X (i.e python3.8 and pip3.8). Note that if the minor version of your new installation is the same as the OS's version (for example if you were installing python3.8.4 and the OS used python3.8.2), then you would need to specify the entire path (/usr/local/bin/pythonX.X) or set an alias to use this version.

User · Answer

It s most strongly dependent on the package distribution system you use   For example  with MacPorts  you can install multiple Python packages and use the pyselect utility to switch the default between them with ease  At all times  you re able to call the different Python interpreters by providing the full path  and you re able to link against all the Python libraries and headers by providing the full paths for those   So basically  whatever way you install the versions  as long as you keep your installations separate  you ll able to run them separately

User · Answer

I m using Mac  amp  the best way that worked for me is using pyenv   The commands below are for Mac but pretty similar to Linux  see the links below    Install pyenv brew update brew install pyenv   Let s say you have python 3 6 as your primary version on your mac   python --version    Output   Python  lt your current version gt    Now Install python 3 7  first list all  pyenv install -l   Let s take 3 7 3   pyenv install 3 7 3   Make sure to run this in the Terminal  add it to    bashrc or    zshrc    export PATH   Users username  pyenv  PATH  eval    pyenv init -     Now let s run it only on the opened terminal shell   pyenv shell 3 7 3   Now run  python --version   Output   Python 3 7 3   And not less important unset it in the opened shell iTerm   pyenv shell --unset   You can run it globally or locally as well

User · Answer

I think it is totally independent  Just install them  then you have the commands e g   usr bin python2 5 and  usr bin python2 6  Link  usr bin python to the one you want to use as default    All the libraries are in separate folders  named after the version  anyway   If you want to compile the versions manually  this is from the readme file of the Python source code      Installing multiple versions      On Unix and Mac systems if you intend to install multiple versions of Python   using the same installation prefix  --prefix argument to the configure   script  you must take care that your primary python executable is not   overwritten by the installation of a different version   All files and   directories installed using  make altinstall  contain the major and minor   version and can thus live side-by-side    make install  also creates     prefix  bin python3 which refers to   prefix  bin pythonX Y   If you intend   to install multiple versions using the same prefix you must decide which   version  if any  is your  primary  version   Install that version using    make install    Install all other versions using  make altinstall        For example  if you want to install Python 2 5  2 6 and 3 0 with 2 6 being   the primary version  you would execute  make install  in your 2 6 build   directory and  make altinstall  in the others

User · Answer

Update 2019  Using asdf  These days I suggest using asdf to install various versions of Python interpreters next to each other   Note1  asdf works not only for Python but for all major languages   Note2  asdf works fine in combination with popular package-managers such as pipenv and poetry   If you have asdf installed you can easily download install new Python interpreters     Install Python plugin for asdf  asdf plugin-add python    List all available Python interpreters  asdf list-all python    Install the Python interpreters that you need  asdf install python 3 7 4 asdf install python 3 6 9   etc       If you want to define the global version  asdf global python 3 7 4    If you want to define the local  project  version     this creates a file  tool-versions in the current directory   asdf local python 3 7 4   Old Answer  Install Python from source  If you need to install multiple versions of Python  next to the main one  on Ubuntu   Mint   should work similar on other Unixs     1  Install Required Packages for source compilation    sudo apt-get install build-essential checkinstall   sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev   2  Download and extract desired Python version  Download Python Source for Linux as tarball and move it to  usr src   Extract the downloaded package in place   replace the  x s with your downloaded version     sudo tar xzf Python-x x x tgz   3  Compile and Install Python Source    cd Python-x x x   sudo   configure   sudo make altinstall   Your new Python bin is now located in  usr local bin  You can test the new version     pythonX X -V Python x x x   which pythonX X  usr local bin pythonX X    Pip is now available for this version as well    pipX X -V pip X X X from  usr local lib pythonX X site-packages  python X X

User · Answer

On Windows they get installed to separate folders   C  python26  and  C  python31   but the executables have the same  python exe  name     I created another  C  python  folder that contains  python bat  and  python3 bat  that serve as wrappers to  python26  and  python31  respectively  and added  C  python  to the PATH environment variable     This allows me to type python or python3 in my  bat Python wrappers to start the one I desire   On Linux  you can use the    trick to specify which version you want a script to use

User · Answer

I did this with anaconda navigator  I installed anaconda navigator and created two different development environments with different python versions   and switch between different python versions by switching or activating and deactivating environments   first install anaconda navigator and then create environments   see help here on how to manage environments  https   docs anaconda com anaconda navigator tutorials manage-environments   Here is the video to do it with conda  https   youtu be EGaw6VXV3GI

User · Answer

How to install different Python versions is indeed OS dependent   However  if you re on linux  you can use a tool like pythonbrew or pythonz to help you easily manage and switch between different versions

[python] Multiple Python versions on the same machine?

Package Managers - user-level

Installation from source - system-wide

Examples related to python