sqshq/sampler · error

errorText.String()

Error message

errorText.String()

What it means

In the basic (non-PTY) interactive shell's execute loop, when the command's timeout fires while stderr output has been accumulated, the shell returns all collected stderr text as a Go error instead of the cleaned stdout. This means the error message you see is literally the command's own stderr, prefixed only by the call-site wrapper (if any). The library throws this so timeouts surface the program's own diagnostics rather than silently dropping them.

Source

Thrown at data/int_basic.go:120

	var resultText strings.Builder
	var errorText strings.Builder

	for {
		select {
		case stdout := <-s.stdoutCh:
			if len(stdout) > 0 {
				resultText.WriteString(stdout)
				resultText.WriteString("\n")
			}
		case stderr := <-s.stderrCh:
			if len(stderr) > 0 {
				errorText.WriteString(stderr)
				errorText.WriteString("\n")
			}
		case <-timeout:
			if errorText.Len() > 0 {
				return "", errors.New(errorText.String())
			}
			return s.item.transform(vtclean.Clean(resultText.String(), false))
		}
	}
}

View on GitHub (pinned to 9bc7ba732d)

Solutions

1. Increase the shell timeout (Item configuration) so the command finishes before the timer fires
2. Fix the underlying command so it does not write to stderr or hang (check the stderr text in the error for the real cause)
3. Reduce or eliminate stderr noise from the command (redirect benign warnings) if stderr presence plus slow run is expected
4. Use PTY mode where supported for better interactive handling, or run the command outside the interactive shell with an explicit timeout wrapper

Example fix

// before
item := item.NewItem(...)
item.Interactive.Type = "basic"
// after (give slow command more time)
item.Interactive.Shell.Timeout = 60 * time.Second

if cmd timeout risk: pre-estimate runtime, e.g. dry-run once with a generous timeout before enabling in config

out, err := shell.execute()
if err != nil {
    log.Printf("command timed out or wrote to stderr: %v", err)
    // fall back to last known good value or skip sample
    return lastValue, nil
}

When it happens

Trigger: Running a command through a basic interactive shell whose runtime exceeds s.timeout while stderr bytes were already collected via errorText; the <-timeout case fires and returns errors.New(errorText.String()).

Common situations: Long-running commands (slow network installs, builds) under a tight per-item timeout config; commands that print warnings to stderr early then hang; Windows/macOS environments where the command blocks on a prompt.

Understand the failure class

Background: Request timed out: what client-side request timeouts mean across libraries (Request timed out, TIMED_OUT, APITimeoutError) — this error's family across 39 libraries.

Related errors

• failed to execute command: %s
• PTY mode is not supported on Windows
• failed to execute command: %s
• panic(err)
• Failed to load the font:

AI-assisted analysis of sqshq/sampler@9bc7ba732d (2026-09-06). Data as JSON: /api/errors/d6f6e527106dbd15. Report an issue: GitHub.