What causes "invalid {} argument: {}" in can1357/oh-my-pi?

Inspect the quoted argument in the message and correct the typo so it is a plain integer or float depending on the seq form used.

can1357/oh-my-pi · error · SeqError

invalid {} argument: {}

Error message

invalid {} argument: {}

What it means

`SeqError::ParseError` from the seq builtin: an operand string could not be parsed as a number. The message is 'invalid {type} argument: {arg}' where the type comes from `parse_error_type(.1)` (e.g. floating-point vs integer) and the offending argument is quoted. It exists so the CLI can report exactly which command-line argument was malformed and why.

Source

Thrown at crates/pi-builtins/src/seq.rs:433

mod error {
//! Errors returned by seq.

// pi-uutils: `translate!` message lookups are literalized with the en-US
// strings from upstream's locales/en-US.ftl.

use thiserror::Error;
use uucore::display::Quotable;

use super::numberparse::ParseNumberError;

#[derive(Debug, Error)]
pub enum SeqError {
	/// An error parsing the input arguments.
	///
	/// The parameters are the [`String`] argument as read from the
	/// command line and the underlying parsing error itself.
	#[error("invalid {} argument: {}", parse_error_type(.1), .0.quote())]
	ParseError(String, ParseNumberError),

	/// The increment argument was zero, which is not allowed.
	///
	/// The parameter is the increment argument as a [`String`] as read
	/// from the command line.
	#[error("invalid Zero increment value: {}", .0.quote())]
	ZeroIncrement(String),

	/// No arguments were passed to this function, 1 or more is required
	#[error("missing operand")]
	NoArguments,

	/// Both a format and equal width where passed to seq
	#[error("format string may not be specified when printing equal width strings")]
	FormatAndEqualWidth,
}

View on GitHub (pinned to 9690622007)

Solutions

Inspect the quoted argument in the message and correct the typo so it is a plain integer or float depending on the seq form used.
Check that shell variables used as operands are set and numeric (`echo "$START"`, or `${START:-0}`).
Strip locale formatting: remove thousands separators and use '.' as the decimal separator.
In code calling the seq API, parse/validate operands yourself first and reject non-numeric strings with your own error before invoking seq.
Quote shell arguments to avoid word-splitting producing extra/empty operands (`seq "$start" "$end"`).

Example fix

// before: unset variable expands to an empty operand
seq $START $END        # -> invalid floating-point argument: ''

// after: default and validate before use
: "${START:=1}"
seq "$START" "$END"

Defensive patterns

Strategy: validation

Validate before calling

fn validate_seq_operand(arg: &str) -> Result<f64, String> {
    let t = arg.trim();
    if t.is_empty() {
        return Err("seq operand is empty (unset variable?)".into());
    }
    t.parse::<f64>().map_err(|_| format!("invalid seq operand: {arg:?}"))
}

Type guard

fn is_parse_error(err: &SeqError) -> bool {
    matches!(err, SeqError::ParseError(_, _))
}

Try / catch

match seq_result {
    Err(SeqError::ParseError(arg, kind)) => {
        eprintln!("seq: fix argument {arg} (expected a number: {kind:?})");
    }
    Err(e) => return Err(e.into()),
    Ok(v) => Ok(v),
}

Prevention

Always quote shell operands (`seq "$start" "$end"`) to prevent word-splitting and empty arguments.
Default or validate shell variables before use: `${START:=1}`.
Use '.' as decimal separator and strip thousands separators / locale formatting.
Pre-parse operands in calling code and reject non-numeric strings with your own error before invoking seq.

When it happens

Trigger: Calling seq (or the library's seq entry point) with a non-numeric operand, e.g. `seq abc`, `seq 1 xyz 10`, arguments with stray whitespace or thousands separators ('1 000'), trailing characters ('10f'), or an empty string as one of start/increment/end operands.

Common situations: Shell variables that are unset or empty expanding to nothing (`seq $START 10` with START unset); passing floats to the integer-only form or vice versa; locale-formatted numbers ('1,5'); copy-pasted arguments with hidden Unicode characters; typos like `seq 1..10`.

Related errors

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/a597839d78841bf3. Report an issue: GitHub.