#include <u.h>#include <libc.h> void	usage(void); voidmain(int argc, char *argv[]){	ulong flag = 0;	char buf[ERRLEN]; 	ARGBEGIN{	case 'a':		flag |= MAFTER;		break;	case 'b':		flag |= MBEFORE;		break;	case 'c':		flag |= MCREATE;		break;	default:		usage();	}ARGEND 	if(argc != 2 || (flag&MAFTER)&&(flag&MBEFORE))		usage(); 	if(bind(argv[0], argv[1], flag) < 0){		errstr(buf);		fprint(2, "bind %s %s: %s\n", argv[0], argv[1], buf);		exits("bind");	}	exits(0);} voidusage(void){	fprint(2, "usage: bind [-b|-a|-c|-bc|-ac] new old\n");	exits("usage");}