rem: rc = sys_read(fd, buf, -1, sizeof(buf) -1);
add: rc = sys_read(fd, -1, buf, sizeof(buf) -1);
context: int cmd_cat(int argc, char *argv[]){	int rc;	int fd;	char buf[257];	if(argc < 2) {		printf("not enough arguments to cat\n");		return 0;	}	fd = sys_open(argv[1], 0);	if(fd < 0) {		printf("cat: sys_open() returned error: %s!\n", strerror(fd));		goto done_cat;	}	for(;;) {		rc = sys_read(fd, buf, -1, sizeof(buf) -1);		if(rc <= 0)			break;		buf[rc] = '\0';		printf("%s", buf);	}	sys_close(fd);done_cat:	return 0;}