Lec-15: Signals in Linux System Programming | SIGINT, SIGTERM, SIGKILL SIGINT vs SIGTERM vs SIGKILL

lecture 15: Signals in Linux System Programming is a complete and in-depth tutorial that explains how Linux signals work internally, how they are used for inter-process communication (IPC), and how signals like SIGINT, SIGTERM, SIGKILL, SIGUSR1, SIGUSR2, SIGSTOP, SIGCONT control process behavior in Linux.

In this video, you will clearly understand what a signal is in Linux, why signals exist, and how the Linux kernel delivers signals to running processes. Signals are one of the most fundamental concepts in Linux system programming, embedded Linux, Linux device drivers, and operating system internals, making this lecture extremely important for students, professionals, and interview preparation.

We start by explaining what happens when you press Ctrl+C, which generates SIGINT, and how applications like shells, servers, and embedded systems handle or ignore this signal. Then we move on to SIGTERM, the graceful termination signal used by system services, init systems, and process managers. You will learn the difference between SIGTERM and SIGKILL, why SIGKILL cannot be caught or ignored, and when it should (and should not) be used.

This lecture also covers SIGUSR1 and SIGUSR2, which are user-defined signals commonly used for custom notifications, parent-child communication, and daemon control in Linux. Practical examples show how a parent process sends signals using the kill() system call, how a child process handles them using signal() and sigaction(), and how signals interact with fork(), exec(), and wait().

You will also learn:

How signal handlers work internally

Why some system calls are interrupted by signals (EINTR)

The difference between blocking signals and ignoring signals

What happens when a signal is delivered during sleep(), wait(), or read()

How signals are handled across exec()

Common mistakes in signal handling

🔍 Topics Covered in This Video

What is a signal in Linux

SIGINT explained (Ctrl+C)

SIGTERM vs SIGKILL (graceful vs force kill)

SIGUSR1 and SIGUSR2 usage

signal() vs sigaction()

kill() system call

Signal handling in parent and child processes

fork(), exec(), wait() with signals

Linux system programming fundamentals

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