What is the role and purpose of signals in the Linux operating system?

Signals in the Linux operating system are mechanisms for asynchronous notification of a process about the occurrence of certain events. They allow processes to respond to external or internal events, such as interrupts, errors, or user requests.

Role of signals:

• Notifying a process about events (e.g., termination of a child process, pressing Ctrl+C).
• Managing processes (e.g., stopping, continuing, terminating).
• Error handling (e.g., division by zero triggers SIGFPE signal).

A process can set a signal handler that executes upon receiving a signal, or use default behavior (termination, ignoring, etc.).

Example of handling SIGINT (Ctrl+C) in C:

#include <signal.h>
#include <stdio.h>
#include <unistd.h>

void handler(int signum) {
    printf("Received signal %d, terminating\n", signum);
    _exit(0);
}

int main() {
    signal(SIGINT, handler);
    while(1) {
        printf("Working...\n");
        sleep(1);
    }
    return 0;
}