AdguardTeam/AdGuardHome · error

got %s without argument

Error message

got %s without argument

What it means

A command-line option that requires a value was the last token on the command line, so the iterator next() returned no value. applyOptWithValue reports which flag is missing its argument.

Source

Thrown at internal/home/options.go:453

	if err != nil {
		return o, eff, fmt.Errorf("applying option %s: %w", arg, err)
	}

	return newOpts, newEff, nil
}

// applyOptWithValue applies argument with value.   next and eff must not
// be nil.
func applyOptWithValue(
	opt cmdLineOpt,
	next func() (int, string, bool),
	o options,
	eff effect,
	arg string,
) (newOpt options, newEff effect, err error) {
	_, val, ok := next()
	if !ok {
		return o, eff, fmt.Errorf("got %s without argument", arg)
	}

	newOpts, err := opt.updateWithValue(o, val)
	if err != nil {
		return o, eff, fmt.Errorf("applying option %s: %w", arg, err)
	}

	return newOpts, eff, nil
}

// findMatchingOpt returns cmdLineOpt which matches the given arg.  ok indicates
// whether the appropriate option was found.
func findMatchingOpt(arg string) (opt cmdLineOpt, ok bool) {
	for _, opt := range cmdLineOpts {
		if argMatches(opt, arg) {
			return opt, true
		}
	}

View on GitHub (pinned to b41aefbe51)

Solutions

1. Append the required value after the flag: -c /path/to/config.yaml
2. Quote and default empty shell variables: -w "${WORKDIR:-/var/lib/adguardhome}"
3. Validate generated command lines in scripts before executing

Example fix

# before
./AdGuardHome -c

# after
./AdGuardHome -c /etc/adguardhome.yaml

// Ensure value-taking flags are never last:
if strings.HasPrefix(arg, "-") && i == len(args)-1 && requiresValue(arg) {
    return fmt.Errorf("flag %s needs a value", arg)
}

When it happens

Trigger: Ending argv with a value-taking flag: ./AdGuardHome -c or ./AdGuardHome --workdir with nothing after it.

Common situations: Shell scripts where a variable expands to empty (-w "$WORKDIR" with WORKDIR unset), or truncated command lines in service unit files.

Related errors

• parsing port: %w
• parsing arg at index %d: %w
• unknown option %s
• applying option %s: %w
• action %q: %w

AI-assisted analysis of AdguardTeam/AdGuardHome@b41aefbe51 (2026-08-27). Data as JSON: /api/errors/eb6fe0fbe69d41aa. Report an issue: GitHub.