The more easy way its by executing the next command:

ls -ls /usr/bin/python*

Output look like this:

/usr/bin/python           /usr/bin/python2.7        /usr/bin/pythonw
/usr/bin/python-config    /usr/bin/python2.7-config /usr/bin/pythonw2.7

Hi @EMP_H ,

Yes, you should be able to switch between python versions. As a standard, it is recommended to use the python3 command or python3.7 to select a specific version. The py.exe launcher will automatically select the most recent version of Python you've installed. You can also use commands like py -3.7 to select a particular version, or py --list to see which versions can be used. HOWEVER, the py.exe launcher will only work if you are using a version of Python installed from python.org. When you install Python from the Microsoft Store, the py command is not included. Since you're using the Microsoft Store version of Python, you should use the python3 (or python3.7) command.

Hope that helped. Please let us know if you have further questions.

Best,
Grace

For information please read this FAQ doc for using python on windows.

There's a command called whereis which does that for you :

 whereis python

You can use python -V (et al.) to show you the version of Python that the python command resolves to. If that's all you need, you're done. But to see every version of python in your system takes a bit more.

In Ubuntu we can check the resolution with readlink -f $(which python). In default cases in 14.04 this will simply point to /usr/bin/python2.7.

We can chain this in to show the version of that version of Python:

$ readlink -f $(which python) | xargs -I % sh -c 'echo -n "%: "; % -V'
/usr/bin/python2.7: Python 2.7.6

But this is still only telling us what our current python resolution is. If we were in a Virtualenv (a common Python stack management system) python might resolve to a different version:

$ readlink -f $(which python) | xargs -I % sh -c 'echo -n "%: "; % -V'
/home/oli/venv/bin/python: Python 2.7.4

This is real output.

The fact is there could be hundreds of different versions of Python secreted around your system, either on paths that are contextually added, or living under different binary names (like python3).

If we assume that a Python binary is always going to be called python<something> and be a binary file, we can just search the entire system for files that match those criteria:

$ sudo find / -type f -executable -iname 'python*' -exec file -i '{}' \; | awk -F: '/x-executable; charset=binary/ {print $1}' | xargs readlink -f | sort -u | xargs -I % sh -c 'echo -n "%: "; % -V'
/home/oli/venv/bin/python: Python 2.7.4
/media/ned/websites/venvold/bin/python: Python 2.7.4
/srv/chroot/precise_i386/usr/bin/python2.7: Python 2.7.3
/srv/chroot/trusty_i386/usr/bin/python2.7: Python 2.7.6
/srv/chroot/trusty_i386/usr/bin/python3.4: Python 3.4.0
/srv/chroot/trusty_i386/usr/bin/python3.4m: Python 3.4.0
/usr/bin/python2.7: Python 2.7.6
/usr/bin/python2.7-dbg: Python 2.7.6
/usr/bin/python3.4: Python 3.4.0
/usr/bin/python3.4dm: Python 3.4.0
/usr/bin/python3.4m: Python 3.4.0
/web/venvold/bin/python: Python 2.7.4

It's obviously a pretty hideous command but this is again real output and it seems to have done a fairly thorough job.