How to Install and Run Different Python Versions in Cmd?

Two major Python versions – python 2 and Python 3 have a different compatibility. The program running on one Python version not necessarily work with another Python version.

So, many times we have to two deal with both the Python version for running different Python projects on the same system.

Let’s see How to Install and Run different Python versions in Cmd prompt.

Installing Different Python Versions on the Same System:

Installation of Python is pretty easy as like any other software you install on your system. You can simply download Python software from its official website and install it.

For more detail, choose below installation steps based on the operating system.

• Python Installation on Windows
• Python Installation on Linux

Follow the same steps for installing Python 2 and Python 3 versions.

Now you have two Python version installed on your system. But, how to choose particular Python version to run your Python code or script.

To run your script in Python version 2:

Simply add the following line of code as the first line to your any Python script.

#!python2

You can print the Python version to ensure it.

#!python2
import platform
print(platform.python_version())

Save it as pyVersion.py (or any file name you suggest). And run the following the command py pyVersion.py

Output

>> py pyVersion.py
2.7.13

To run your script in Python version 3:

Add this line to your Python script.

#!python3

Run the same program again by changing the first line with the above line of code.

#!python3
import platform
print(platform.python_version())

Output

>> py pyVersion.py
3.7.0

How does it actually work?

Here, the first line of the code is called as Shebang Lines. And it starts with #!.

The main purpose of the Shebang line is to indicate how a script should be executed on the system.

If you are Linux or Unix user, these operating systems have native support for executing Shebang lines. Same shebang lines, you can use with Python script on windows as well.

This simple one line of code to run different python versions in cmd on the same system helps me a lot for many of the Python projects which has a dependency for running on particular Python version.

As this line is part of Python script, it works for any operating system like WIndow, Linux, and iOS.

I do write Python code every day and share my knowledge. Check out my complete Python tutorial for more of such tricks.

Happy Pythoning!