#include <u.h>#include <libc.h> enum {	Nsec = 1000*1000*1000,}; voidusage(void){	fprint(2, "usage: date [-itun] [-f fmt] [seconds]\n");	exits("usage");} voidmain(int argc, char *argv[]){	int nflg, uflg;	char *fmt;	vlong s, ns;	Tzone *tz;	Tm tm; 	nflg = 0;	uflg = 0;	tz = nil;	fmt =  "WW MMM _D hh:mm:ss ZZZ YYYY";	tmfmtinstall(); 	ARGBEGIN{	case 'n':	nflg = 1;				break;	case 'u':	uflg = 1;				break;	case 't':	fmt = "YYYY-MM-DDThh:mm:ssZZ";		break;	case 'i':	fmt = "YYYY-MM-DD";			break;	case 'f':	fmt = EARGF(usage());			break;	default:	usage();	}ARGEND 	s = 0;	ns = 0;	switch(argc) {	case 0:		ns = nsec();		s = ns/Nsec;		ns = ns%Nsec;		break;	case 1:		s = strtoll(argv[0], nil, 0);		ns = 0;		break;	default:		usage();		break;	} 	if(!uflg && (tz = tzload("local")) == nil)		sysfatal("timezone: %r");	if(tmtimens(&tm, s, ns, tz) == nil)		sysfatal("now: %r"); 	if(nflg)		print("%lld\n", tmnorm(&tm));	else		if(print("%τ\n", tmfmt(&tm, fmt)) == -1)			sysfatal("%r");	exits(0);}