First Python Program

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Interactive Mode Programming:

Invoking the interpreter without passing a script file as a parameter brings up the following prompt:

$ python

Python 2.4.3 (#1, Nov 11 2010, 13:34:43)

[GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> 

Type the following text to the right of the Python prompt and press the Enter key:

>>> print "Hello, Python!";

If you are running new version of Python, then you would need to use print statement with parenthesis like print ("Hello, Python!");. However at Python version 2.4.3, this will produce following result:

Hello, Python!

Script Mode Programming:

Invoking the interpreter with a script parameter begins execution of the script and continues until the script is finished. When the script is finished, the interpreter is no longer active.
Let us write a simple Python program in a script. All python files will have extension .py. So put the following source code in a test.py file.

print "Hello, Python!";

Here, I assumed that you have Python interpreter set in PATH variable. Now, try to run this program as follows:

$ python test.py

This will produce the following result:

Hello, Python!

Let's try another way to execute a Python script. Below is the modified test.py file:

#!/usr/bin/python

print "Hello, Python!";

Here, I assumed that you have Python interpreter available in /usr/bin directory. Now, try to run this program as follows:

$ chmod +x test.py     # This is to make file executable

$./test.py

This will produce the following result:

Hello, Python!