bettercap/bettercap · error

can't parse string from '%s'

Error message

can't parse string from '%s'

What it means

Syntax guard in DuckyParser.parseString: a STRING/STR instruction line has no space separating the token from the payload, so there is no string argument to return — the Ducky script line is malformed.

Source

Thrown at modules/hid/duckyparser.go:59

func (p DuckyParser) parseNumber(from string) (int, error) {
	idx := strings.IndexRune(from, ' ')
	if idx == -1 {
		return 0, fmt.Errorf("can't parse number from '%s'", from)
	}

	num, err := strconv.Atoi(from[idx+1:])
	if err != nil {
		return 0, fmt.Errorf("can't parse number from '%s': %v", from, err)
	}

	return num, nil
}

func (p DuckyParser) parseString(from string) (string, error) {
	idx := strings.IndexRune(from, ' ')
	if idx == -1 {
		return "", fmt.Errorf("can't parse string from '%s'", from)
	}
	return from[idx+1:], nil
}

func (p DuckyParser) lineIs(line string, tokens ...string) bool {
	for _, tok := range tokens {
		if strings.HasPrefix(line, tok) {
			return true
		}
	}
	return false
}

func (p DuckyParser) Parse(kmap KeyMap, path string) (cmds []*Command, err error) {
	lines := []string{}
	source := []string{}
	reader := (chan string)(nil)

View on GitHub (pinned to 8eca2820f3)

Solutions

1. Put a space between STRING and the text to type, e.g. 'STRING hello world'
2. Fix empty STRING lines by removing them or adding the payload

When it happens

Trigger: Thrown at modules/hid/duckyparser.go:59 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of bettercap/bettercap@8eca2820f3 (2026-09-02). Data as JSON: /api/errors/3f178d3c880d4eda. Report an issue: GitHub.