What causes "expected an int, not "%s"" in matryer/xbar?

Supply a plain base-10 integer, e.g. | length=42

expected an int, not "%s"

Error message

expected an int, not "%s"

What it means

parseInt converts a plugin parameter value (e.g. dropdown widths, trim lengths) into an int using strconv.ParseInt in base 10. This error is thrown when the string is not a valid integer, with the offending value included in the message.

Source

Thrown at pkg/plugins/item_params.go:312

		// Matches #RGB #RGBA #RRGGBB #RRGGBBAA
		if !colorRegexp.Match([]byte(s)) {
			return "", errors.Errorf(`invalid hex format "%s"`, s)
		}
		return s, nil
	}
	hexValue, valid := namedColors[s]
	if !valid {
		return "", errors.Errorf(`invalid named color "%s"`, s)
	}
	return hexValue, nil
}

// parseInt parses an int from a string, returning a nice
// error if it fails.
func parseInt(s string) (int, error) {
	i, err := strconv.ParseInt(s, 10, 64)
	if err != nil {
		return 0, errors.Errorf(`expected an int, not "%s"`, s)
	}
	return int(i), nil
}

// truncate shrinks a string if it's too long.
func truncate(s string, max int) string {
	truncated, err := ansi.Truncate(s, max-1)
	if err != nil {
		// If, for some reason, there's an error when
		// parsing, do what we used to do
		runes := []rune(s)
		if max > 0 && len(runes) > max {
			s = string(runes[:max-1]) + "…"
		}
		return s
	}
	length, _ := ansi.Length(truncated)
	if length == max-1 {

View on GitHub (pinned to d624239058)

Solutions

Supply a plain base-10 integer, e.g. | length=42
Strip unit suffixes in the plugin script: ${SIZE%px} or size=$((size))
Round floats to integers before emitting the parameter
Guard unset variables with a default: ${LENGTH:-0}

Example fix

// before
echo "Item | length=${WIDTH%px}"   // '10px' -> 10 fails if suffix remains
// after
LENGTH=${WIDTH%px}; echo "Item | length=${LENGTH:-0}"

Defensive patterns

Strategy: validation

Validate before calling

n, err := strconv.Atoi(strings.TrimSpace(val))
if err != nil {
    val = "0" // sanitize before emitting the parameter
}

Prevention

Emit bare base-10 integers only — no suffixes, commas or decimals
Default numeric variables: ${LEN:-0}
Pre-strip unit suffixes (px, %) in the plugin script

When it happens

Trigger: setValueByKey receives a non-numeric value for an int parameter — e.g. | length=abc, | dropdown=true, | size=10px, an empty value, or a value with thousands separators like 1,000.

Common situations: Plugin authors passing suffixed numbers (px, %), booleans or floats (1.5) where a plain int is expected; shell variables containing text; locale-formatted numbers with separators.

Related errors

AI-assisted analysis of matryer/xbar@d624239058 (2026-09-02). Data as JSON: /api/errors/066bead18583b840. Report an issue: GitHub.