CODEWITHSUNDEEP
csignals
teemo ammo
teemo ammo

Reputation: 11

Print message before SIGINT

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

/* A signal handling function that simply prints
   a message to standard error. */
void handler(int code) {
    fprintf(stderr, "Signal %d caught\n", code);
}

int main() {
    // Declare a struct to be used by the sigaction function:
    struct sigaction newact;

    // Specify that we want the handler function to handle the
    // signal:
    newact.sa_handler = handler;

    // Use default flags:
    newact.sa_flags = 0;

    // Specify that we don't want any signals to be blocked during
    // execution of handler:
    sigemptyset(&newact.sa_mask);

    // Modify the signal table so that handler is called when
    // signal SIGINT is received:
    sigaction(SIGINT, &newact, NULL);

    // Keep the program executing long enough for users to send
    // a signal:
    int i = 0;

    for (;;) {
        if ((i++ % 50000000) == 0) {
            fprintf(stderr, ".");
        }
    }

    return 0;
}

When I press ctrl-c, I want my program to print "Signal %d caught\n" message then exit normally as it would when pressing ctrl-c.

./test ..............................^CSignal 2 caught .................^CSignal 2 caught ..........................................^Z [2]+ Stopped ./test

Right now it just prints the message but doesn't exit the program right after.

Upvotes: 0

Views: 1349

Answers (1)

Gam
Gam

Reputation: 694

That is because the default behavior of ctrl+c is to exit the program. But by using sigaction() you are managing the behavior yourself. So if you want the program to end, you can add an exit() call.

void handler(int code) {
    fprintf(stderr, "Signal %d caught\n", code);
    exit(code);
}

Upvotes: 1

Related Questions