#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>


int main(int argc, char **argv) {
    printf("before fork my pid %d\n", getpid());
    pid_t childpid;
    for (int i=0; i < 2; i++) {    
        childpid = fork();
        if (childpid == -1)
            perror("fork"), exit(0);
    }

    if (childpid == 0) {
        printf("child: my pid %d, my parent's pid is %d\n", getpid(), getppid());
        //raise(SIGKILL);
        void *w = *(void **)NULL;
        exit(144);
    } else {
        for (int i=0; i < 2; i++) {
            int status = 0;
            pid_t childexited = wait(&status);
            if (childexited == -1) {
                perror("wait");
                continue;
            }
            
            if (WIFEXITED(status)) {
                /* normal */
                printf("parent: my pid %d, my child's pid is %d (exited child is %d) status %d\n",
                       getpid(), childpid, childexited, WEXITSTATUS(status));
            } else if (WIFSIGNALED(status)) {
                /* crash or kill */
                printf("parent: my pid %d, my child's pid is %d (exited child is %d) what signal %d\n",
                       getpid(), childpid, childexited, WTERMSIG(status));
            } else {
                printf("?");
            }
        }
        
    }
}