stdin = true
			b, err = io.ReadAll(stdinReader)
		} else {
			b, err = os.ReadFile(strings.TrimSpace(fn))
		}
		if err != nil {
			return "", err
		}
		multiple := false
		multiple, err = hasMultipleIOPs(string(b))
		if err != nil {
			return "", err
		}
		if multiple {
			return "", fmt.Errorf("input file %s contains multiple IstioOperator CRs, only one per file is supported", fn)
		}