# apply cmd to args list read from stdin# obcimplement Xargs; include "sys.m";	sys: Sys;include "draw.m";include "sh.m";include "bufio.m";	bufio: Bufio;	Iobuf: import bufio; Xargs: module{        init:	fn(ctxt: ref Draw->Context, argv: list of string);}; stderr: ref Sys->FD; usage(){	sys->fprint(stderr, "Usage: xargs command [command args] <[list of last command arg]\n");} init(ctxt: ref Draw->Context, args: list of string){	sys = load Sys Sys->PATH;	stderr = sys->fildes(2);	bufio = load Bufio Bufio->PATH;	if(bufio == nil){		sys->fprint(stderr, "xargs: can't load Bufio: %r\n");		exit;	}	if(args != nil)		args = tl args;	if (args == nil) {		usage();		return;	}	cmd := hd args;	args = tl args;	if(len cmd < 4 || cmd[len cmd -4:]!=".dis")		cmd += ".dis";	sh := load Command cmd;	if (sh == nil){		cmd = "/dis/"+cmd;		sh = load Command cmd;	}	if (sh == nil){		sys->fprint(stderr, "xargs: can't load %s: %r\n", cmd);		exit;	} 	stdin := sys->fildes(0);	if(stdin == nil){		sys->fprint(stderr, "xargs: no standard input\n");		exit;	}	b := bufio->fopen(stdin, Bufio->OREAD);	while((t := b.gets('\n')) != nil){		(nil, rargs) := sys->tokenize(t, " \t\n");		if (rargs == nil)			continue;		if (args == nil)			rargs = cmd :: rargs;		else			rargs = append(cmd :: args, rargs);		sh->init(ctxt, rargs);		# BUG: process environment?	}} reverse[T](l: list of T): list of T{	t: list of T;	for(; l != nil; l = tl l)		t = hd l :: t;	return t;} append(h, t: list of string) : list of string{	r := reverse(h);	for(; r != nil; r = tl r)		t = hd r :: t;	return t;}