Play with c fork and pstree

fork-pstree.c

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

void create_process(int current_level)
{
  int parent = (int)getpid();
  int child = (int)fork();
  // printf("ps_forked %d %d\n", current_level,(int)getpid());
  if (child > 0)
  {
    // I am parent
    int status;
    waitpid(child, &status, 0);
  }
  else
  {
    // I am child
    if (current_level > 0)
    {
      create_process(current_level - 1);
    }
    else
    {
      // I am the last child, exec pstree now.
      char bottom_str[100];
      sprintf(bottom_str, "%d", (int)getpid());
      execlp("pstree", "pstree", "-s", bottom_str, NULL);
    }
  }
}

int main(int argc, char *argv[])
{
  int total_level;
  sscanf(argv[1], "%d", &total_level);
  create_process(total_level - 1);
}