junegunn/fzf · error

unexpected value for %s: %s

Error message

unexpected value for %s: %s

What it means

A standalone (no-value) option was given a value. During parsing, certain options are recognized as flags with no argument; if the parser then finds a leftover attached value, it raises 'unexpected value for <arg>: <value>'.

Source

Thrown at src/options.go:3503

			} else if match, value := optString(arg, "-d"); match {
				opts.Delimiter = delimiterRegexp(value)
			} else if match, value := optString(arg, "-n"); match {
				if opts.Nth, err = splitNth(value); err != nil {
					return err
				}
			} else if match, _ := optString(arg, "-s"); match {
				opts.Sort = 1 // Don't care
			} else if match, value := optString(arg, "-m"); match {
				if opts.Multi, err = atoi(value); err != nil {
					return err
				}
			} else {
				return errors.New("unknown option: " + arg)
			}
		}

		if val != nil {
			return errors.New("unexpected value for " + arg + ": " + *val)
		}
	}
	*index += len(allArgs)

	if opts.HeaderLines < 0 {
		return errors.New("header lines must be a non-negative integer")
	}

	if opts.HscrollOff < 0 {
		return errors.New("hscroll offset must be a non-negative integer")
	}

	if opts.ScrollOff < 0 {
		return errors.New("scroll offset must be a non-negative integer")
	}

	if opts.Tabstop < 1 {
		return errors.New("tab stop must be a positive integer")

View on GitHub (pinned to bd4efa277b)

Solutions

1. Remove the value: use the flag alone (e.g. -s not -s 1)
2. For boolean-style long options, drop the '=...' suffix
3. Check fzf --help to see which options take a value

Example fix

# before
fzf -s 1
# after
fzf -s

// Shell: strip '=...' from valueless flags
valueless='-s --sync --no-sort --reverse +s +i +x'
args=()
for a in "$@"; do
  k="${a%%=*}"
  [[ $valueless == *"$k"* && "$a" == *=* ]] && a="$k"
  args+=("$a")
done
exec fzf "${args[@]}"

When it happens

Trigger: Writing something like -s 1 or --sync=true where the option takes no value: after the option is consumed, the leftover value (val != nil) triggers errors.New("unexpected value for " + arg + ": " + *val) at options.go:3503. Also triggered by '--flag=value' syntax for boolean-style flags in this branch.

Common situations: Applying '=value' syntax to flags that accept no value; copy-pasting option lines from other tools; assuming all long options take arguments.

Related errors

• unknown option: %s
• unsupported style preset: %s
• at least one of 'file' or 'dir' should be specified
• unable to put non-printable character
• unknown action: ${spec}

AI-assisted analysis of junegunn/fzf@bd4efa277b (2026-08-15). Data as JSON: /api/errors/edc6022fa038650a. Report an issue: GitHub.