How to Capture Linux Signal in Python

Many times developers need to terminate scripts that are running, using Ctrl+C or other signals. But this is often processed by OS, and not the actual script. But sometimes you may need the script to be able to receive and handle system signals from within the script itself. In this article, we will learn how to capture Linux signal in Python.

How to Capture Linux Signal in Python

Python provides an inbuilt library called signal that allows you to easily capture and work with signals. Let us create a sample python script to capture Linux signal.

$ vi test.py

Add the following lines to set the execution environment and import required libraries.

#!/usr/bin/env python
import signal
import sys

Next, we define the signal handler.

def signal_handler(sig, frame):
    print('You pressed Ctrl+C!')
    sys.exit(0)

Next, we register this signal handler using signal.signal(). We specify two arguments in it – the signal that will call the handler, and the name of the handler.

signal.signal(signal.SIGINT, signal_handler)
print('Press Ctrl+C')
signal.pause()

We use the signal.pause() function to cause the process to sleep until it receives a signal. Save and close the file.

Putting it all together.

#!/usr/bin/env python
import signal
import sys

def signal_handler(sig, frame):
    print('You pressed Ctrl+C!')
    sys.exit(0)

signal.signal(signal.SIGINT, signal_handler)
print('Press Ctrl+C')
signal.pause()

Make the file executable.

$ sudo chmod +x test.py

Run the file with the following command.

$ python test.py

In this article, we have learnt how to capture Linux signal in python script.

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