11.c

/*
============================================================================
Name : 11
Author : Piyush Singh
Description : Write a program to ignore a SIGINT signal then reset the default action of the SIGINT signal -
use sigaction system call.
Date: 19th Sep, 2025.
============================================================================
*/
#include <stdio.h>      // For printf()
#include <signal.h>     // For sigaction()
#include <unistd.h>     // For sleep()

int main() 
{
    struct sigaction sa;

    // Step 1: Ignore SIGINT
    sa.sa_handler = SIG_IGN;         // Ignore handler
    sigemptyset(&sa.sa_mask);        // No blocked signals
    sa.sa_flags = 0;                 // No special flags

    sigaction(SIGINT, &sa, NULL);
    printf("🚫 SIGINT is now ignored for 10 seconds. Try pressing Ctrl+C...\n");

    for (int i = 0; i < 10; i++) 
    {
        printf("⌛ Still ignoring SIGINT... (%d)\n", i + 1);
        sleep(1);
    }

    // Step 2: Reset SIGINT to default behavior
    sa.sa_handler = SIG_DFL;         // Default handler
    sigaction(SIGINT, &sa, NULL);
    printf("🔁 SIGINT reset to default. Ctrl+C will now terminate the program.\n");

    // Step 3: Wait again so user can test Ctrl+C
    while (1) 
    {
        printf("🟢 Waiting... Press Ctrl+C to exit.\n");
        sleep(2);
    }

    return 0;
}

// If you press Ctrl+C during the first 10 seconds, nothing happens. 
// After that, it terminates the program as expected.

/*
Output:
╰─ ./11                                                                       ─╯
🚫 SIGINT is now ignored for 10 seconds. Try pressing Ctrl+C...
⌛ Still ignoring SIGINT... (1)
⌛ Still ignoring SIGINT... (2)
⌛ Still ignoring SIGINT... (3)
⌛ Still ignoring SIGINT... (4)
⌛ Still ignoring SIGINT... (5)
^C⌛ Still ignoring SIGINT... (6)
^C⌛ Still ignoring SIGINT... (7)
^C⌛ Still ignoring SIGINT... (8)
^C⌛ Still ignoring SIGINT... (9)
⌛ Still ignoring SIGINT... (10)
🔁 SIGINT reset to default. Ctrl+C will now terminate the program.
🟢 Waiting... Press Ctrl+C to exit.
^C
*/