How to run multiple Python versions on Windows

Question

I had two versions of Python installed on my machine  versions 2 6 and 2 5   I want to run 2 6 for one project and 2 5 for another    How can I specify which I want to use   I am working on Windows XP SP2

User · Answer

For example for 3 6 version type py -3 6    If you have also 32bit and 64bit versions  you can just type py -3 6-64 or py -3 6-32

User · Answer

let s say if we have python 3 7 and python 3 6 installed  they are respectively stored in following folder by default  C  Users name AppData Local Programs Python Python36 C  Users name AppData Local Programs Python Python37 if we want to use cmd prompt to install run command in any of the above specific environment do this  There should be python exe in each of the above folder  so when we try running any file for ex   see image1  python hello py  we call that respective python exe  by default it picks lower version of file   means in this case it will use from python 3 6   image so if we want to run using python3 7  just change the  exe file name  for ex  if I change to python37 exe and i want to use python3 7 to run hello py I will use python37 hello py   or if i want to use python3 7 by default i will change the python exe filename in python3 6 folder to something else   so that it will use python3 7 each time when I use only python hello py

User · Answer

Adding two more solutions to the problem    Use pylauncher  if you have Python 3 3 or newer there s no need to install it as it comes with Python already  and either add shebang lines to your scripts       c   path to Python 2 5  python exe - for scripts you want to be run with Python 2 5    c   path to Python 2 6  python exe - for scripts you want to be run with Python 2 6  or instead of running python command run pylauncher command  py  specyfing which version of Python you want   py -2 6     version 2 6 py -2     latest installed version 2 x py -3 4     version 3 4 py -3     latest installed version 3 x     Install virtualenv and create two virtualenvs    virtualenv -p c   path to Python 2 5  python exe  path where you want to have virtualenv using Python 2 5 created   name of virtualenv   virtualenv -p c   path to Python 2 6  python exe  path where you want to have virtualenv using Python 2 6 created   name of virtualenv   for example  virtualenv -p c  python2 5 python exe c  venvs 2 5  virtualenv -p c  python2 6 python exe c  venvs 2 6  then you can activate the first and work with Python 2 5 like this c  venvs 2 5 activate and when you want to switch to Python 2 6 you do    deactivate   c  venvs 2 6 activate

User · Answer

Running a different copy of Python is as easy as starting the correct executable  You mention that you ve started a python instance  from the command line  by simply typing python    What this does under Windows  is to trawl the  PATH  environment variable  checking for an executable  either batch file   bat   command file   cmd  or some other executable to run  this is controlled by the PATHEXT environment variable   that matches the name given  When it finds the correct file to run the file is being run   Now  if you ve installed two python versions 2 5 and 2 6  the path will have both of their directories in it  something like PATH c  python 2 5 c  python 2 6 but Windows will stop examining the path when it finds a match   What you really need to do is to explicitly call one or both of the applications  such as c  python 2 5 python exe or c  python 2 6 python exe   The other alternative is to create a shortcut to the respective python exe calling one of them python25 and the other python26  you can then simply run python25 on your command line

User · Answer

install python   C  Python27 C  Python36  environment variable   PYTHON2 HOME  C  Python27 PYTHON3 HOME  C  Python36 Path   PYTHON2 HOME   PYTHON2 HOME  Scripts  PYTHON3 HOME   PYTHON3 HOME  Scripts   file rename   C  Python27 python exe   C  Python27 python2 exe C  Python36 python exe   C  Python36 python3 exe  pip   python2 -m pip install package python3 -m pip install package

User · Answer

The easiest way to run multiple versions of python on windows is described below as follows -  1 Download the latest versions of python from python org downloads by selecting the relevant version for your system   2 Run the installer and select Add python 3 x to the path to set path automatically in python 3  you just have to click the checkbox   For python 2 open up your python 2 installer  select whatever preferences you want but just remember to set Add python exe to path to Will be installed on local hard drive  Now just click next and wait for the installer to finish   3 When both the installations are complete  Right click on my computer--Go to properties--Select advanced system settings--Go to environment variables--Click on new under System variables and add a new system variable with variable name as PY PYTHON and set this variable value to 3  Now click on OK and you should be done   4 Now to test this open the command prompt  Once you are in there type python or py  It should open up python3   5 Now exit out of python3 by typing exit    Now type py -2 it should open python 2   If none of this works then restart the computer and if the problem still persists then uninstall everything and repeat the steps   Thanks

User · Answer

Using a batch file to switch  easy and efficient on windows 7  I use this   In the environment variable dialog  C  Windows System32 SystemPropertiesAdvanced exe    In the section user variables   added  pathpython  to the path environment variable removed any references to python pathes    In the section system variables   removed any references to python pathes    I created batch files for every python installation  exmple for 3 4 x64  Name            SetPathPython34x64       ToExecuteAsAdmin bat      -  just to remember   Content of the file          Set PathPython C  Python36AMD64 Scripts  C  Python36AMD64  C  Tcl bin       setx PathPython  PathPython    To switch between versions  I execute the batch file in admin mode            The changes are effective for the SUBSEQUENT command prompt windows OPENED       So I have exact control on it

User · Answer

When you install Python  it will not overwrite other installs of other major versions  So installing Python 2 5 x will not overwrite Python 2 6 x  although installing 2 6 6 will overwrite 2 6 5   So you can just install it  Then you call the Python version you want  For example   C  Python2 5 Python exe   for Python 2 5 on windows and  C  Python2 6 Python exe   for Python 2 6 on windows  or    usr local bin python-2 5   or    usr local bin python-2 6   on Windows Unix  including Linux and OS X    When you install on Unix  including Linux and OS X  you will get a generic python command installed  which will be the last one you installed  This is mostly not a problem as most scripts will explicitly call  usr local bin python2 5 or something just to protect against that  But if you don t want to do that  and you probably don t you can install it like this     configure make sudo make altinstall   Note the  altinstall  that means it will install it  but it will not replace the python command   On Windows you don t get a global python command as far as I know so that s not an issue

User · Answer

Just call the correct executable

User · Answer

Using the Rapid Environment Editor  you can push to the top the directory of the desired Python installation  For example  to start python from the c  Python27 directory  ensure that c  Python27 directory is before or on top of the c  Python36 directory in the Path environment variable  From my experience  the first python executable found in the Path environment is being executed  For example  I have MSYS2 installed with Python27 and since I ve added C  MSYS2 to the path before C  Python36  the python exe from the C  MSYS2     folder is being executed

User · Answer

I strongly recommend the pyenv-win project     Thanks to kirankotari s work  now we have a Windows version of pyenv

User · Answer

cp c  python27 bin python exe as python2 7 exe  cp c  python34 bin python exe as python3 4 exe  they are all in the system path  choose the version you want to run  C  Users username gt python2 7 Python 2 7 8  default  Jun 30 2014  16 03 49   MSC v 1500 32 bit  Intel   on win 32 Type  help    copyright    credits  or  license  for more information   gt  gt  gt   C  Users username gt python3 4 Python 3 4 1  v3 4 1 c0e311e010fc  May 18 2014  10 38 22   MSC v 1600 32 bit Intel   on win32 Type  help    copyright    credits  or  license  for more information   gt  gt  gt

User · Answer

As per  alexander you can make a set of symbolic links like below   Put them somewhere which is included in your path so they can be easily invoked   gt  cd c  bin  gt  mklink python25 exe c  python25 python exe  gt  mklink python26 exe c  python26 python exe   As long as c  bin or where ever you placed them in is in your path you can now go   gt  python25

User · Answer

I thought this answer might be helpful to others having multiple versions of python and wants to use pipenv to create virtual environment   navigate to the project directory  and run py - python version  pip install pipenv  example  py -3 6 pip install pipenv run pipenv --python  version  to create the virtual environment in the version of the python you desire  example  pipenv --python 3 6 run pipenv shell to activate your virtual environment

User · Answer

You can create different python development environments graphically from Anaconda Navigator   I had same problem while working with different python versions so I used anaconda navigator to create different python development environments and used different python versions in each environments   Here is the help documentation for this   https   docs anaconda com anaconda navigator tutorials manage-environments

User · Answer

One easy way for this is that you can use py -3 8 -m pip install virtualenv here -3 8 goes with your  version number  After installing the virtualenv  you can create the virtual environment of your application using py -3 8 -m virtualenv  your env name  then cd to venv  enter activate This would activate the python version you like  Just change the version number to use a different python version

User · Answer

From Python 3 3 on  there is the official Python launcher for Windows  http   www python org dev peps pep-0397    Now  you can use the   pythonX to determine the wanted version of the interpreter also on Windows  See more details in my another comment or read the PEP 397   Summary  The py script py launches the Python version stated in    or Python 2 if    is missing  The py -3 script py launches the Python 3

User · Answer

Here s a quick hack    Go to the directory of the version of python you want to run Right click on python exe Select  Create Shortcut  Give that shortcut a name to call by  I use p27  p33 etc   Move that shortcut to your home directory C  Users Your name  Open a command prompt and enter name of your shortcut lnk I use p27 lnk

[python] How to run multiple Python versions on Windows

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