What causes "The command `{cmd_eval}` exited with non-zero." in sigoden/aichat?

Re-run the same command manually and check its exit code/stderr

The command ` ` exited with non-zero.

Error message

The command `{cmd_eval}` exited with non-zero.

What it means

In the branch of run_loader_command where the command writes output to a file, a non-zero exit status produces this bail (stderr is not captured in this path). The message tells you which command failed but not why.

Solutions

Re-run the same command manually and check its exit code/stderr
Fix the loader's arguments or input so it exits 0
Ensure the output path is writable and the loader can create the file
Check that required env vars for the loader are set in the spawning environment

Example fix

// before: failing flags
loader = ["pandoc", "--bad-flag"]
// after
loader = ["pandoc", "-f", "html", "-t", "markdown"]

Defensive patterns

Strategy: try-catch

Validate before calling

// smoke-test the command with the same args and check exit code
const r = spawnSync(cmd, args, { stdio: 'ignore' });
if (r.status !== 0) console.error(`${cmd} exits ${r.status}`);

Try / catch

try {
  const contents = await loadFromCommand(cmd, args);
} catch (e) {
  if (e.message.includes('exited with non-zero')) {
    // re-run manually for stderr since this path hides it
  }
}

Prevention

Ensure commands exit 0 on success and write to the expected output file
Avoid flags that only work in interactive shells
Set required env vars in the service environment, not just your shell

When it happens

Trigger: A loader command configured to write to an output file exits with status != 0 during load_with_command / load_protocol_path / fetch_with_loaders.

Common situations: Loader crashes or rejects the input silently; command not found behaviors handled earlier but other failures (bad flags, permissions) exit non-zero; environment differences between interactive shell and spawned process.

Understand the failure class

Background: "git command failed": what it means when a tool shells out to git and git exits non-zero — this error's family across 21 libraries.

Related errors

AI-assisted analysis of sigoden/aichat@82976d349a (2026-09-09). Data as JSON: /api/errors/3b267937235b4368. Report an issue: GitHub.

Appendix: source

Thrown at src/utils/command.rs:149

        let (success, stdout, stderr) =
            run_command_with_output(cmd, args, None).with_context(|| {
                format!("Unable to run `{cmd_eval}`, Perhaps '{cmd}' is not installed?")
            })?;
        if !success {
            let err = if !stderr.is_empty() {
                stderr
            } else {
                format!("The command `{cmd_eval}` exited with non-zero.")
            };
            bail!("{err}")
        }
        Ok(stdout)
    } else {
        let status = run_command(cmd, args, None).with_context(|| {
            format!("Unable to run `{cmd_eval}`, Perhaps '{cmd}' is not installed?")
        })?;
        if status != 0 {
            bail!("The command `{cmd_eval}` exited with non-zero.")
        }
        let contents = std::fs::read_to_string(&outpath)
            .context("Failed to read file generated by the loader")?;
        Ok(contents)
    }
}

pub fn edit_file(editor: &str, path: &Path) -> Result<()> {
    let mut child = Command::new(editor).arg(path).spawn()?;
    child.wait()?;
    Ok(())
}

pub fn append_to_shell_history(shell: &str, command: &str, exit_code: i32) -> io::Result<()> {
    if let Some(history_file) = get_history_file(shell) {
        let command = command.replace('\n', " ");
        let now = now_timestamp();
        let history_txt = if shell == "fish" {

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