uutils/coreutils · error · clap::Error

realpath-invalid-empty-operand

Error message

realpath-invalid-empty-operand

What it means

realpath rejects an empty operand at argument-parsing time. The custom clap value parser (`parse_ref`) checks `value.is_empty()` and raises a ValueValidation error carrying the localized message "realpath-invalid-empty-operand", because realpath has no meaningful answer for an empty path.

Source

Thrown at src/uu/realpath/src/realpath.rs:54

const OPT_RELATIVE_BASE: &str = "relative-base";

const ARG_FILES: &str = "files";

/// Custom parser that validates `OsString` is not empty
#[derive(Clone, Debug)]
struct NonEmptyOsStringParser;

impl TypedValueParser for NonEmptyOsStringParser {
    type Value = OsString;

    fn parse_ref(
        &self,
        _cmd: &Command,
        _arg: Option<&Arg>,
        value: &OsStr,
    ) -> Result<Self::Value, clap::Error> {
        if value.is_empty() {
            let mut err = clap::Error::new(clap::error::ErrorKind::ValueValidation);
            err.insert(
                clap::error::ContextKind::Custom,
                clap::error::ContextValue::String(translate!("realpath-invalid-empty-operand")),
            );
            return Err(err);
        }
        Ok(value.to_os_string())
    }
}

impl ValueParserFactory for NonEmptyOsStringParser {
    type Parser = Self;

    fn value_parser() -> Self::Parser {
        Self
    }
}

View on GitHub (pinned to 85295bbf78)

Solutions

1. Pass a real path operand to realpath
2. In shell scripts, default or check the variable first: `${dir:?dir is empty}`
3. Filter empty entries from path lists before invoking realpath

Example fix

// before
let dir = env::var("TARGET_DIR").unwrap_or_default();
// after
let dir = env::var("TARGET_DIR").expect("TARGET_DIR must be set to a non-empty path");

if operand.is_empty() {
    eprintln!("realpath: invalid operand: empty string");
    std::process::exit(1);
}
realpath(operand)?;

fn is_valid_operand(s: &OsStr) -> bool { !s.is_empty() }

match result {
    Err(e) if e.to_string().contains("realpath-invalid-empty-operand") => default_path(),
    other => other?,
}

When it happens

Trigger: Running `realpath ''` or otherwise passing an empty string as a path argument (e.g. from an unset shell variable, `$FOO` that expands to nothing, or a script that builds a path list containing a blank entry).

Common situations: Unquoted/unset environment variables in shell scripts (`realpath "$dir"` with `dir=`), pipeline output that yields blank lines, or programmatic invocation of the utility with empty argv entries.

Related errors

• InvalidValue clap error for unmatched argument value
• InvalidUtf8 clap error for non-UTF-8 argument value

AI-assisted analysis of uutils/coreutils@85295bbf78 (2026-08-31). Data as JSON: /api/errors/fc505aa82d23182c. Report an issue: GitHub.