is_dev_fd_file(char_u *fname)
{
    return (STRNCMP(fname, "/dev/fd/", 8) == 0
	    && VIM_ISDIGIT(fname[8])
	    && *skipdigits(fname + 9) == NUL
	    && (fname[9] != NUL
		|| (fname[8] != '0' && fname[8] != '1' && fname[8] != '2')));
}