Detect script exit in Python

Python is a scripting language. This means that a Python code is executed line by line with the help of a Python interpreter. When a python interpreter encounters an end-of-file character, it is unable to retrieve any data from the script. This EOF(end-of-file) character is the same as the EOF that informs the end of the file while reading data from a file in Python.

To detect a script exit, we can use the built-in the atexit library of Python. The atexit module is used to register or unregister functions that handle clean-up. The functions that are registered by atexit are automatically called at interpreter termination.

Syntax: atexit.register(fun, *args, **kwargs)

Parameters: First the function name is mentioned and then any arguments for that function is passed. The parameters are separated using ‘, ‘.

Return: This function returns the called fun and hence the calling can be traced.

The following example demonstrates how atexit can be used to detect script exit:

import atexit
n = 2
print("Value of n:",n)
atexit.register(print,"Exiting Python Script!")

Output:

Value of n: 2
Exiting Python Script!

In this simple program, we passed a print function and a string as arguments to atexit.register function. This registered the print statement as a function that will be invoked on script termination.

We can also use register() method as a decorator.

import atexit 
n = 2
print("Value of n:",n)
# Using register() as a decorator 
@atexit.register 
def goodbye(): 
    print("Exiting Python Script!") 

Output:

Value of n: 2
Exiting Python Script!

Python provides various functions that can be used to exit a python script, you can check them here.