/* program to send signal to child */

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

void sighandler_child(int sig_num){
    printf("\n\nSignal %d caught by the process with pid =  %d\n",sig_num,getpid());
}

int main(){

    pid_t pid;
    int termstatus;
    pid = fork();

    if(pid==-1)
        printf("Error whlie creating child process");

    //parent sends the signal
    if(pid > 0){

        sleep(1); //to let the child establish the handler before parent starts execution
        printf("about to send signal to child\n");
        kill(pid,SIGUSR2);
        printf("sent signal to child\n");
        wait(&termstatus);
        printf("\n\nParent: Child terminated...now I am gonna terminate\n\n");
    }

    if(pid==0){

        /*   to establish the signal handler..
            the type of the second argument is "sighandler_t" which is actually a pointer to a function...
             void (*sighandler_t)(int)

        */

        if(signal(SIGUSR2,sighandler_child) == SIG_ERR){
            printf("\n\nError while establishing signal handler\n\n");
            return 2;
        }

        sleep(3); //to let the child wait for the parent to send signal

        printf("\nChild: I am exiting\n\n");

    }



    return 0;
}