#include <u.h>#include <libc.h>#include <auth.h> extern int newnsdebug; char	*defargv[] = { "/bin/rc", "-i", nil };char	*namespace = nil; voidusage(void){	fprint(2, "usage: %s [-d] [-n namespace] [cmd [args...]]\n", argv0);	exits("usage");} voidrun(char **a){	exec(a[0], a); 	if(a[0][0] != '/' && a[0][0] != '#' &&	  (a[0][0] != '.' || (a[0][1] != '/' &&		             (a[0][1] != '.' ||  a[0][2] != '/'))))		exec(smprint("/bin/%s", a[0]), a); 	sysfatal("exec: %s: %r", a[0]);} voidmain(int argc, char *argv[]){	ARGBEGIN{	case 'd':		newnsdebug = 1;		break;	case 'n':		namespace = EARGF(usage());		break;	default:		usage();	}ARGEND 	if(procsetuser("none") < 0)		sysfatal("can't become none: %r");	if(newns("none", namespace) < 0)		sysfatal("can't build namespace: %r"); 	if(argc == 0)		argv = defargv; 	run(argv);}