be-one.c

#define _GNU_SOURCE

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

#define STACK_SIZE 0x20000

int fn (void *data) {
  printf("child: %d\n", getpid());
  char *cmd[] = { "/bin/sh", NULL };
  execv(cmd[0], cmd);

  return 1;
}


int main (void) {
  void *stack = malloc (STACK_SIZE);
  int test = clone(fn, stack + STACK_SIZE, CLONE_NEWNS|CLONE_NEWPID, NULL);
  printf("test %d\n", test);
  waitpid(-1, NULL, __WALL);

  return 0;
}