implement Ps; include "sys.m";include "draw.m"; FD, Dir: import Sys;Context: import Draw; Ps: module{	init:	fn(ctxt: ref Context, argv: list of string);}; sys: Sys;stderr: ref FD; init(nil: ref Context, nil: list of string){	sys = load Sys Sys->PATH; 	stderr = sys->fildes(2); 	sys->pctl(Sys->FORKNS, nil);	if(sys->chdir("/prog") < 0){		sys->fprint(stderr, "ps: can't chdir to /prog: %r\n");		raise "fail:no /prog";	}	fd := sys->open(".", sys->OREAD);	if(fd == nil) {		sys->fprint(stderr, "ps: cannot open /prog: %r\n");		raise "fail:no /prog";	} 	for(;;) {		(n, d) := sys->dirread(fd);		if(n <= 0){			if(n < 0) {				sys->fprint(stderr, "ps: error reading /prog: %r\n");				raise "fail:error on /prog";			}			break;		}		for(i := 0; i < n; i++)			if(d[i].name[0] >= '0' && d[i].name[0] <= '9')				ps(int d[i].name);			}} ps(pid: int){	proc := string pid+"/status";	fd := sys->open(proc, sys->OREAD);	if(fd == nil) {	# process must have died		# sys->fprint(stderr, "ps: /prog/%s: %r\n", proc);		return;	}	buf := array[128] of byte;	n := sys->read(fd, buf, len buf);	if(n > 0)		sys->print("%s\n", string buf[0:n]);}