// can run this zombie process as the "sole" process inside of a container
// (bash might be reaping children)
// even though 30 zombies don't have parents, after 5 minutes the container
// exist and there are no zombies in sight at the host level process tables

#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
 
int main ()
{
  int i;
  pid_t parent_pid;
  pid_t child_pid;
 
  // spawn 30 zombie grand children
  for (i=30; i>0; i--) {
    parent_pid = fork();
    if (parent_pid > 0) {
      // run a child
      child_pid = fork ();
      if (child_pid > 0) {
        // child
        sleep (60);
      }
      else {
        // parent
        exit (0);
      }
    }
    else {
      // grand parent (actual exec) just sleeps for 5 min
      // doesn't waitpid or reaps anything
      if (i == 1) {
        sleep (300);
      }
    }
  }

  return 0;
}