Understanding the "main() Function Doesn't Run" Issue

Consider the following Python script:

#! /usr/bin/python

def main():
    print("boo")

When run in Python 3.3, this script silently fails to produce any output. This can be puzzling.

Troubleshooting the Root Cause

The problem lies in the fact that defining a function in Python does not automatically execute its code. The code within the main() function needs to be explicitly called.

In this particular script, the main() function is never called. As a result, the print statement inside it remains unexecuted.

Solution: Calling the Function

To fix the issue, you simply need to call the main() function after defining it. Here's the corrected version of the script:

def main():
    print("boo")

main()  # Call the function explicitly

Now, when you run the script, it should correctly print "boo" on the console.

Additional Notes:

• The example script provided uses the shebang line #! /usr/bin/python to specify the Python interpreter to use when running the script.
• The chmod 775 script command sets the permissions for the script file, making it executable.
• The ./script command runs the script file as a regular program.