can1357/oh-my-pi · error · WcError

when reading file names from standard input, no file name of

Error message

when reading file names from standard input, no file name of '-' allowed

What it means

WcError::StdinReprNotAllowed fires when the literal '-' (stdin marker) appears among the file names read from a `--files0-from` list. Since the names themselves come from stdin, a nested '-' stdin reference is undefined and coreutils forbids it.

Source

Thrown at crates/pi-builtins/src/wc.rs:787

		}
	}
}

impl TotalWhen {
	fn is_total_row_visible(self, num_inputs: usize) -> bool {
		match self {
			Self::Auto => num_inputs > 1,
			Self::Always | Self::Only => true,
			Self::Never => false,
		}
	}
}

#[derive(Debug, Error)]
enum WcError {
	#[error("extra operand {}\nfile operands cannot be combined with --files0-from", extra.quote())]
	FilesDisabled { extra: Cow<'static, OsStr> },
	#[error("when reading file names from standard input, no file name of '-' allowed")]
	StdinReprNotAllowed,
	#[error("invalid zero-length file name")]
	ZeroLengthFileName,
	#[error("{path}:{idx}: invalid zero-length file name")]
	ZeroLengthFileNameCtx { path: Cow<'static, str>, idx: usize },
	#[error("{context}: {source}")]
	Io {
		context: String,
		#[source]
		source:  io::Error,
	},
}

impl WcError {
	fn zero_len(ctx: Option<(&Input, usize)>) -> Self {
		match ctx {
			Some((input, idx)) => {
				let path = match input {

View on GitHub (pinned to 9690622007)

Solutions

1. Remove the '-' entry from the --files0-from list file
2. If stdin content must be counted, run a separate `wc` on stdin (possibly writing it to a temp file and adding that to the list)
3. Filter the list before use: `grep -zvx -- '-' list.txt > list.clean`

Example fix

// before: list.txt contains "a.txt\0-\0b.txt\0"
// after
grep -zvx -- '-' list.txt > list.clean && wc --files0-from=list.clean

fn validate_files0_list(bytes: &[u8]) -> Result<(), String> {
    let names: Vec<&[u8]> = bytes.split(|&b| b == 0).filter(|s| !s.is_empty()).collect();
    if names.iter().any(|n| n == b"-") {
        Err("'-' is not allowed inside --files0-from input".into())
    } else { Ok(()) }
}

When it happens

Trigger: Running `wc --files0-from=list.txt` where list.txt contains a NUL-delimited '-' entry (e.g. produced by a pipeline that echoed '-'), or passing '-' through find/xargs output into the list.

Common situations: Accidentally including '-' in generated file lists; reusing an operand list built for plain `wc -` invocations; scripts substituting '-' as a placeholder for stdin.

Related errors

• invalid zero-length file name
• extra operand {} file operands cannot be combined with --fil
• {path}:{idx}: invalid zero-length file name
• Overlapping replacements detected; refine pattern to avoid a
• when reading file names from standard input, no file name of

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/2e287186b3da4ed4. Report an issue: GitHub.