#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>


pid_t newChildProcess(){
  pid_t child_pid = fork(); //create childProcess
  if(child_pid==0){
    /*Child Process*/
    printf("Child Process\n");
    close(mypipefd[1]);
    read(mypipefd[0],buf1,sizeof(buf1));
    b = buf1;
    b++;
  execl(argv[0],argv[0],b,NULL);
  }else{
    /*Parent Process*/
    close(mypipefd[0]); // close useless stdin stream
    write(mypipefd[1], hex_num_a,sizeof(hex_num_a)); //stream to child
    (void)wait(&status); // wait for child
    printf("Parent Process\n");
  }
}

int main(int argc, char *argv[]) {
  pid_t child_pid1;
  pid_t child_pid2;
  int mypipefd[2];
  int ret;
  char buf[20];
  int status;
  char *b = argv[1];//argv[1]
  char *hex_num_a = argv[1];
  char *hex_num_b = argv[2];

  char buf1[4];
  memset(buf1,0,sizeof(buf1));
  ret  = pipe(mypipefd);

  if(ret== -1){
    perror("pipe");
    exit(1);
  }

  if(b[0] !='1'){
    exit(EXIT_FAILURE);
  }

  child_pid11 = fork();

  if(child_pid1==0){
    /*Child Process*/
    if(child 1){
      printf("Child Process\n");
      close(mypipefd[1]);
      read(mypipefd[0],buf1,sizeof(buf1));
      printf("danach %s\n", buf1);
      //fprintf(stdout, "danach %s\n", buf1);
      b = buf1;
      b++;
      fprintf(stderr,"hallo %s\n",b);
    }else if(child 2){

    }
    execl(argv[0],argv[0],b,NULL);
  }else{
    /*Parent Process*/

    /*create 4 child processes*/
    newChildProcess();
    newChildProcess();
    newChildProcess();
    /* ------------- */
    close(mypipefd[0]);
    child_pid2 = fork();
    fprintf(stderr, "davor %s\n", hex_num_a);
    write(mypipefd[1], hex_num_a,sizeof(hex_num_a));
    (void)wait(&status);
    printf("Parent Process\n");
  }
  /* code */
  return 0;
}