how to run a python script

Before writing <a href="https://python.org">Python</a> scripts, you should be able to run them. If you run a Python script, Python makes sure the computer understands the code: it interprets.

Any Python script should end with the .py extension. So program names could be:

hello.py
world.py
sort_names.py

The way to execute Python differs on systems (Linux,Mac,Windows), but comes down to the same idea. Any script will do, you can use the <a href="https://pythonbasics.org/execute-python-scripts/">hello world</a> script.

Windows

On Windows, you likely installed Python in C:\Python..\python.exe But your program is most probably somewhere else, like on your desktop. First open a command prompt (Win+R, cmd or command.exe) You can run it with this command:

C:\Python35\python.exe C:\Users\Username\Desktop\my_python_script.py

On older versions of windows, Python is not installed by default. If that's the case, install it first.

On Mac OS X or Linux

If you use Apple Mac or Linux, Python is often installed by default. On top of the program, you can add one of these lines:

#!/usr/bin/env python

#!/usr/bin/env python3

This defines that you want to use Python environment. Save your file (hello.py).

Then in the command line, make it executable:

chmod +x hello.py

Then you can run it like any other program. An alternative is to run it with the python interpreter:

    python hello.py

Alternatives

Working from the command line can be quite challenging. For a single file you can do it, but for larger apps this gets cumbersome.

Most developers use an app to develop, a so called <a href="https://pythonbasics.org/getting-started/#PythonIDE">IDE</a>. This lets you work with multiple files easily, run with a keyboard shortcut and other simplifications.

Alt Text

Sometimes people work directly in the Python shell, sometimes named <a href="https://pythonprogramminglanguage.com/repl/">REPL</a>. This lets you interact with Python, but doesn't require a file.

To open the Python shell, you simply type 'python' in the command prompt. That sets you into the shell.

➜  ~ python3
Python 3.7.5 (default, Nov 20 2019, 09:21:52) 
[GCC 9.2.1 20191008] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

To exit the shell, press Ctrl+Z.

Related links:

<a href="https://python.org/">Python language homepage</a>
<a href="https://pythonbasics.org/">Python tutorial</a>