bash-container.txt

root@89de118f2aa3:~# ps -ef ; date ; nohup ./zombie & ; sleep 2 ; ps -ef ; sleep 65 ; date ; ps -ef                                                                                                                                   
bash: syntax error near unexpected token `;'
root@89de118f2aa3:~# ps -ef ; date ; (nohup ./zombie &) ; sleep 2 ; ps -ef ; sleep 65 ; date ; ps -ef                                                                                                                                 
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 16:41 ?        00:00:00 /bin/bash
root       364     1  0 16:47 ?        00:00:00 ps -ef
Wed May 20 16:47:37 UTC 2015
nohup: appending output to 'nohup.out'
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 16:41 ?        00:00:00 /bin/bash
root       367     1  0 16:47 ?        00:00:00 ./zombie
root       369   367  0 16:47 ?        00:00:00 [zombie] <defunct>
root       370     1  0 16:47 ?        00:00:00 ps -ef
Wed May 20 16:48:44 UTC 2015
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 16:41 ?        00:00:00 /bin/bash
root       373     1  0 16:48 ?        00:00:00 ps -ef
root@89de118f2aa3:~# 

bash-host.txt

docker@testbox:~$ date ; ps -ef | grep zombie
Wed May 20 16:48:03 UTC 2015
 9281 root     ./zombie
 9283 root     [zombie]
 9297 docker   grep zombie
docker@testbox:~$ date ; ps -ef | grep zombie
Wed May 20 16:48:56 UTC 2015
 9312 docker   grep zombie
docker@testbox:~$ uptime
 16:49:42 up 1 day, 20:59,  2 users,  load average: 0.00, 0.01, 0.04

super-zombie.c

// 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;
}

zombie.c

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

int main ()
{
  pid_t child_pid;

  child_pid = fork ();
  if (child_pid > 0) {
    sleep (60);
  }
  else {
    exit (0);
  }
  return 0;
}