Cannot Use Python 2 from Command Line

Question

I recently tried to uninstall Python 3.5.2 and installed Python 3.6.0. I used to use python in the command line to run Python 3.5.2 from the command line, and py to run Python 2.7.12. Now, python runs Python 3.5.2, and py runs Python 3.6.0. I am running Windows 10, and python3, python2, py2, and py3 do not do anything.

In the new launcher that's distributed with 3.6, running py.exe on the command line now runs the highest version of Python 3.x that's installed. To run Python 2 instead, use py -2. To make this the default, set the environment variable PY_PYTHON=2. — Eryk Sun
– Eryk Sun, Commented Dec 31, 2016 at 23:39
using a package manager like Anaconda can simplify the process of switching versions or using multiple versions on your computer. you can read more HERE — mark jay
– mark jay, Commented Dec 31, 2016 at 23:42

Mark Tolonen · Accepted Answer · 2017-01-01 00:06:08Z

5

Don't bother adding Python to the path. Just use:

py            Run highest version of Python (override with PY_PTYHON environment variable).
py -2         Run highest version of Python 2.
py -3         Run highest verssion of Python 3.
py -2.7       Run Python 2.7.
py -2.7-32    Run python 2.7 32-bit when on a 64-bit system.

More: https://docs.python.org/3.6/using/windows.html#python-launcher-for-windows

Note you can also specify in scripts which version to use as well with, for example:

#!python2
#!python3
#!python2.7

answered Jan 1, 2017 at 0:06

Mark Tolonen

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1 Comment

Eryk Sun Over a year ago

Note that if you're using the old, pre-3.6 version of the launcher, it defaults to running the highest version of Python 2, if installed, and otherwise the highest version of Python 3. This was changed in 3.6 to prefer Python 3. However, for virtual shebangs in scripts, such as #!python and #!/usr/bin/python, the new version of the launcher still maps "python" to Python 2 for the sake of Unix compatibility.

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