juicedata/juicefs · error

option %s requires a value

Error message

option %s requires a value

What it means

Returned while rewriting FUSE-style mount options into CLI flags (handleSysMountArgs) when an -o token is a bare name that is neither a known no-arg option nor a known JuiceFS flag. The option requires a value which was not supplied in 'name=value' form, so the mount arguments are rejected up front.

Source

Thrown at cmd/main.go:177

			opt = strings.TrimSpace(opt)
			if opt == "" || opt == "background" || utils.StringContains(sysOptions, opt) {
				continue
			}
			// Lower case option name is preferred, but if it's the same as flag name, we also accept it
			if strings.Contains(opt, "=") {
				fields := strings.SplitN(opt, "=", 2)
				if flagName, ok := optionToCmdFlag[fields[0]]; ok {
					newArgs = append(newArgs, fmt.Sprintf("--%s=%s", flagName, fields[1]))
				} else if _, ok := cmdFlagsLookup[fields[0]]; ok {
					newArgs = append(newArgs, fmt.Sprintf("--%s=%s", fields[0], fields[1]))
				} else {
					fuseOptions = append(fuseOptions, opt)
				}
			} else if flagName, ok := optionToCmdFlag[opt]; ok {
				newArgs = append(newArgs, fmt.Sprintf("--%s", flagName))
			} else if isBool, ok := cmdFlagsLookup[opt]; ok {
				if !isBool {
					return nil, fmt.Errorf("option %s requires a value", opt)
				}
				newArgs = append(newArgs, fmt.Sprintf("--%s", opt))
				if opt == "debug" {
					fuseOptions = append(fuseOptions, opt)
				}
			} else {
				fuseOptions = append(fuseOptions, opt)
			}
		}

		parseFlag = false
	}
	if len(fuseOptions) > 0 {
		newArgs = append(newArgs, "-o", strings.Join(fuseOptions, ","))
	}
	newArgs = append(newArgs, args[1], args[2])
	logger.Debug("Parsed mount args: ", strings.Join(newArgs, " "))
	return newArgs, nil

View on GitHub (pinned to c9a67b23e8)

Solutions

1. Pass the option in name=value form, e.g. -o cache-size=2048
2. Check the option name against supported mount options

for i, a := range args {
    if strings.HasPrefix(a, "--") {
        if v, ok := valueFlags[a]; ok && (i+1 >= len(args) || strings.HasPrefix(args[i+1], "--")) {
            return fmt.Errorf("%s requires a value", a)
        }
    }
}

if err := mountCmd.Run(); err != nil {
    if strings.Contains(err.Error(), "requires a value") {
        log.Fatalf("supply the option's value: %v", err)
    }
}

When it happens

Trigger: Thrown at cmd/main.go:177 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of juicedata/juicefs@c9a67b23e8 (2026-09-06). Data as JSON: /api/errors/f11e3505649c68e7. Report an issue: GitHub.