Question

What I want to do is create a parent process that lasts for 5 seconds. I also want it to send a SIGUSR1 signal every second. On this signal I want the child to do something.

The code that I put together so far is:

void alarmHandler(int sig) {
    printf("\nalarm called\n");
    exit(0);
}


void childHandler(int sig) {
    printf("child called");
    signal(SIGUSR1, childHandler);
}

int main() {
    pid_t val;

    if((val = fork())) { //parinte
        signal(SIGALRM, alarmHandler);
        printf("parent");
        alarm(5);
        while(1) {
            kill(val, SIGUSR1);
            sleep(1);
        }
    }else { 
        signal(SIGUSR1, childHandler);
        printf("child");
    }

    return 0;
}  

What I get is:

child
parent
alarm called  

What I want:

child 
parent
child called
child called
child called
child called
child called
alarm called

Answer 1

Your parent has the while loop. The child does the following:

signal(SIGUSR1, childHandler);
printf("child");

And then exits.

If it does receive SIGUSR before the exit, this will also be executed

printf("child called");
signal(SIGUSR1, childHandler);

Therefore you have a race condition as the number of child called is printed.

Just put a while (1) {} after the printf("child");