How can I create a child child?

Question

How can I create a child's child's child? How can I do this 10 times. In the code below, the parent is fixed and the children are formed. How can I ensure that the child I want to have a child?

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

int main() 
{ 
    for(int i=0;i<5;i++) // loop will run n times (n=5) 
    { 
        if(fork() == 0) 
        { 
            printf("[son] pid %d from [parent] pid %d\n",getpid(),getppid()); 
            exit(0); 
        }else{
        printf("parrent");
        }
    } 
    for(int i=0;i<5;i++) // loop will run n times (n=5) 
    wait(NULL); 

}

Answer 1

The following should serve as a basic example of what you're attempting to do:

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

int nSubprocess_count = 0;
int nFork_result;

int main() 
  { 
  nFork_result = fork();
  while(nFork_result == 0)
    {
    printf("child %d from parent %d\n", getpid(), getppid()); 

    nSubprocess_count += 1;

    if(nSubprocess_count < 10)
      nFork_result = fork();
    else
      break;
    }

  if(nFork_result != 0)
    printf("parent %d\n", getpid());

  sleep(5);
  }

When run this produces output similar to:

parent 4522
child 4523 from parent 4522
parent 4523
child 4524 from parent 4523
parent 4524
child 4525 from parent 4524
parent 4525
child 4526 from parent 4525
parent 4526
child 4527 from parent 4526
parent 4527
child 4528 from parent 4527
parent 4528
child 4529 from parent 4528
parent 4529
child 4530 from parent 4529
parent 4530
child 4531 from parent 4530
parent 4531
child 4532 from parent 4531

As you can see, each child process forks one additional child process.

OnlineGDB here