#include <stdio.h>
#include <sys/mount.h>

int main(int argc, char **argv) {
	if (argc < 2) {
		fprintf(stderr, "usage: %s <mountpoint>\n", argv[0]);
		return 20;
	}

	if (umount2(argv[1], MNT_FORCE) < 0) {
		perror("umount2");
		return 20;
	}

	return 0;
}