Question

This is my code for interrupting a process with a signal.

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

int main(void){
    void sigint_handler(int sig); /* prototype */
    char s[200];

    if(signal(SIGINT, sigint_handler) == SIG_ERR){
        perror("signal");
        exit(1);
    }

    printf("Enter a string:\n");

    if(gets(s) == NULL)
        perror("gets");
    else
        printf("You entered: \"%s\"\n", s);

    return 0;
}

void sigint_handler(int sig){
    printf("Not this time!\n");
}

Question is how do I capture signal such as SIGINT, SIGKILL, SIGHUP and SIGTERM?

Answer 1

The argument int sig received by your sigint_handler function is the signal that was caught. Constants defining the values are in <signal.h>. So, for example

void sigint_handler(int sig){
    if (sig == SIGINT)
        printf("That was a SIGINT!\n");
}