How to kill a child process by the parent process?

Question

I create a child process using a fork(). How can the parent process kill the child process if the child process cannot complete its execution within 30 seconds?

Answer 1

Try something like this:

#include 

pid_t child_pid = -1 ; //Global

void kill_child(int sig)
{
    kill(child_pid,SIGKILL);
}

int main(int argc, char *argv[])
{
    signal(SIGALRM,(void (*)(int))kill_child);
    child_pid = fork();
    if (child_pid > 0) {
     /*PARENT*/
        alarm(30);
        /*
         * Do parent's tasks here.
         */
        wait(NULL);
    }
    else if (child_pid == 0){
     /*CHILD*/
        /*
         * Do child's tasks here.
         */
    }
}