How to switch between python 2 7 to python 3 from command line

Question

I m trying to find the best way to switch between the two python compilers  2 7 to 3 3  I ran the python script from the cmd like this      python ex1 py   Where do I set the  python  environment in the window s environment variable to point to either python 3 3 or 2 7   I am wondering if there is an easy way to switch between the two versions from the cmd line

User · Answer

There is an easier way than all of the above; You can use the PY_PYTHON environment variable. From inside the cmd.exe shell;

For the latest version of Python 2

set PY_PYTHON=2

For the latest version of Python 3

set PY_PYTHON=3

If you want it to be permanent, set it in the control panel. Or use setx instead of set in the cmd.exe shell.

User · Answer

They are 3 ways you can achieve this using the py command  py-launcher  in python 3  virtual environment or configuring your default python system path  For illustration purpose  you may see tutorial https   www youtube com watch v ynDlb0n27cw amp t 38s

User · Answer

In case you have both python 2 and 3 in your path  you can move up the Python27 folder in your path  so it search and executes python 2 first

User · Answer

You can try to rename the python executable in the python3 folder to python3  that is if it was named python formally    it worked for me

User · Answer

For Windows 7  I just rename the python exe from the Python 3 folder to python3 exe and add the path into the environment variables  Using that  I can execute python test script py and the script runs with Python 2 7 and when I do python3 test script py  it runs the script in Python 3   To add Python 3 to the environment variables  follow these steps -    Right Click on My Computer and go to Properties  Go to Advanced System Settings  Click on Environment Variables and edit PATH and add the path to your Python 3 installation directory    For example

User · Answer

No need for  quot tricks quot    Python 3 3 comes with PyLauncher  quot py exe quot   installs it in the path  and registers it as the  quot  py quot  extension handler   With it  a special comment at the top of a script tells the launcher which version of Python to run    python2 print  quot hello quot   Or   python3 print  quot hello quot    From the command line  py -3 hello py  Or py -2 hello py  py hello py by itself will choose the latest Python installed  or consult the PY PYTHON environment variable  e g  set PY PYTHON 3 6  See Python Launcher for Windows

[python] How to switch between python 2.7 to python 3 from command line?

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