Binary Process Tree using fork

[EEJonhEE]

Hello everyone,

I am trying create a 4-level binary process tree using fork(). This means one parent process spawns 2 children, which spawn 4 grandchildren (2 each), which spawn 8 great grandchildren (2 each). I cannot use pipes. So far I have managed to get 3 (slightly correct) levels. That is, 1 parent, 1 child, 2 grandchildren. I've been working one this for days, please help. Thank you.

main()
{ 
  int stat;
  int returnPid;
  int i;
  
  returnPid = fork();

  if (returnPid == -1) 
  {
     perror("can't fork"); exit(1);
  }
  
		else if (returnPid == 0)
		{  // Child 
             
		  for (i=0; i<2; i++)
		  {
		  		 
		    if ((returnPid = fork()) == 0)
		    { // GrandChild
		    
		    
		      printf("GrandChild: child pid = % d, my pid = %d, parent pid = %d \n",
                          returnPid, getpid(), getppid());
		      exit(0);
     		    }
              }
		
		 wait();
            
		 printf("Child: child pid = % d, my pid = %d, parent pid = %d \n",
                          returnPid, getpid(), getppid());
		
             exit(0);
            
            }
     
		else 
		{  // Parent 
          		 
		  wait();
		
		  printf("Parent: child pid = %d, my pid = %d, parent pid = %d \n ",
                          returnPid, getpid(), getppid(0));
                   
		  exit(0);
            }
}

Here's my output:

GrandChild: child pid = 0, my pid = 5748, parent pid = 8524
Child: child pid = 5992, my pid = 8524, parent pid = 540
GrandChild: child pid = 0, my pid = 5992, parent pid = 8524
Parent: child pid = 8524, my pid = 540, parent pid = 3852

[melkiy]

Write

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

Then you'll get some compilation errors that might prevent you from rude mistakes.

Be aware that function wait() waits for only one (any) child to terminate.