rtk-ai/rtk · error

Failed to relay stdin

Error message

Failed to relay stdin: {}

What it means

`rtk pipe` (with passthrough mode) relays everything from stdin to stdout using `std::io::copy`. If the copy from stdin fails — broken pipe on stdout, I/O error on the input descriptor — pipe_cmd.rs:259 wraps the io::Error into `anyhow!("Failed to relay stdin: {}", e)`. It signals that raw stdin relaying was interrupted by an OS-level I/O failure.

Solutions

1. Ensure the downstream consumer reads all input before exiting (avoid `| head` truncation), or tolerate the error as expected SIGPIPE behavior.
2. Check that stdin is a readable, valid source (not a closed/unusable descriptor) before invoking `rtk pipe --passthrough`.
3. Retry the pipeline; if it persists without a downstream early-exit, inspect disk/terminal health and report an rtk bug.

Example fix

// before (shell)
cat big.log | rtk pipe --passthrough | head -n 5

// after (shell)
cat big.log | rtk pipe --passthrough | sed -n '1,5p;$p'
// or capture full output before truncating
rtk pipe --passthrough < big.log > out.txt && head -n 5 out.txt

# ensure downstream consumer will keep reading
command -v head >/dev/null && echo 'avoid early-exiting consumers like `| head`'

if ! cat data | rtk pipe --passthrough > out.txt 2>err.txt; then
  grep -q 'Failed to relay stdin' err.txt && echo 'downstream closed early; retry without truncation'
fi

When it happens

Trigger: Calling `rtk pipe --passthrough` (passthrough=true) while `std::io::copy(&mut stdin, &mut stdout)` fails: stdout consumer has exited/closed the pipe (EPIPE), or reading stdin hits an I/O error. Raised from `pipe_cmd::run` at src/cmds/system/pipe_cmd.rs:259.

Common situations: Piping into `rtk pipe --passthrough | head -n1` so head closes the pipe early; terminal/SSH session disconnecting mid-stream; redirected stdin from a file or device that errors during read.

Related errors

• Failed to read stdin
• stdin exceeds byte limit
• hook stdin exceeds byte limit

AI-assisted analysis of rtk-ai/rtk@0924356b4c (2026-09-19). Data as JSON: /api/errors/bad2ea4e8522b017. Report an issue: GitHub.

Appendix: source

Thrown at src/cmds/system/pipe_cmd.rs:259

}

fn identity_filter(input: &str) -> String {
    input.to_string()
}

fn apply_filter(filter_fn: fn(&str) -> String, input: &str) -> String {
    std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| filter_fn(input))).unwrap_or_else(
        |_| {
            eprintln!("[rtk] warning: filter panicked — passing through raw output");
            input.to_string()
        },
    )
}

pub fn run(filter_name: Option<&str>, passthrough: bool) -> Result<()> {
    if passthrough {
        std::io::copy(&mut std::io::stdin(), &mut std::io::stdout())
            .map_err(|e| anyhow::anyhow!("Failed to relay stdin: {}", e))?;
        return Ok(());
    }

    let mut buf = String::new();
    std::io::stdin()
        .take((RAW_CAP + 1) as u64)
        .read_to_string(&mut buf)
        .map_err(|e| anyhow::anyhow!("Failed to read stdin: {}", e))?;
    if buf.len() > RAW_CAP {
        anyhow::bail!("stdin exceeds {} byte limit", RAW_CAP);
    }

    let filter_fn = match filter_name {
        Some(name) => resolve_filter(name).ok_or_else(|| {
            anyhow::anyhow!(
                "Unknown filter '{}'. Available: cargo-test, pytest, go-test, go-build, \
                 ctest, tsc, vitest, grep, rg, find, fd, git-log, git-diff, git-status, \
                 log, mypy, ruff-check, ruff-format, sqlfluff-lint, prettier, phpunit, pest, \

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