#include <u.h>#include <libc.h> voidaddflags(Fmt *fmt, char *flags){	char *p, *p0;	int single;	Rune r; 	single = 0;	for(p=flags; *p; ){		p += chartorune(&r, p);		if(*p == ',' || *p == 0){			if(!single){				fmtprint(fmt, " [-");				single = 1;			}			fmtprint(fmt, "%C", r);			if(*p == ',')				p++;			continue;		}		while(*p == ' ')			p++;		if(single){			fmtprint(fmt, "]");			single = 0;		}		p0 = p;		p = strchr(p0, ',');		if(p == nil)			p = "";		else			*p++ = 0;		fmtprint(fmt, " [-%C %s]", r, p0);	}	if(single)		fmtprint(fmt, "]");	} voidmain(void){	Fmt fmt;	char buf[512];	char *argv0, *args, *ptargs, *flags, *ptflags, *p;		argv0 = getenv("0");	if((p = strrchr(argv0, '/')) != nil)		argv0 = p+1;	flags = getenv("flagfmt");	ptflags = getenv("ptflagfmt");	args = getenv("args");	ptargs = getenv("ptargs"); 	if(argv0 == nil){		fprint(2, "aux/usage: $0 not set\n");		exits("$0");	}	if(flags == nil)		flags = "";	if(ptflags == nil)		ptflags = "";	if(args == nil)		args = ""; 	fmtfdinit(&fmt, 2, buf, sizeof buf);	fmtprint(&fmt, "usage: %s", argv0);	if(ptargs != nil)		fmtprint(&fmt, " [%s]", ptargs);	else if(ptflags[0])		addflags(&fmt, ptflags);	if(flags[0])		addflags(&fmt, flags);	if(args)		fmtprint(&fmt, " %s", args);	fmtprint(&fmt, "\n");	fmtfdflush(&fmt);	exits("usage");}