#include <u.h>#include <libc.h> voidmain(int argc, char *argv[]){	int r;	char *mnted, *mtpt; 	argv0 = argv[0];	switch (argc) {	case 2:		mnted = nil;		mtpt = argv[1];		break;	case 3:		mnted = argv[1];		mtpt = argv[2];		break;	default:		SET(mnted, mtpt);		fprint(2, "usage: unmount mountpoint\n");		fprint(2, "       unmount mounted mountpoint\n");		exits("usage");	} 	/* unmount takes arguments in the same order as mount */	r = unmount(mnted, mtpt);	if(r < 0)		sysfatal("%s: %r", mtpt);	exits(0);}