# Bash Cookbook — Testing for an Interactive Shell (O'Reilly)

## Metadata

| Field | Value |
|---|---|
| Institute | Molodetz Institute — Research & Retrieval Division |
| Subject | shell-multiplexer-auto-attach |
| Document type | Source Dossier |
| Tier | 1 |
| Source title | Bash Cookbook, "Use the following case" excerpt |
| Source URL | https://www.oreilly.com/library/view/bash-cookbook/0596526784/ch01s10.html |
| Source publisher / author | O'Reilly Media (Bash Cookbook) |
| Source type | vendor docs |
| Source date (published) | Unknown — not stated |
| Date researched | 2026-10-09 |
| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
| Research method | web search synthesis |
| Confidence | Medium |
| Status | Active |

## Summary

An independent, published-book confirmation of the `$-` test, explicitly stating it as the *preferred* method over checking whether `$PS1` is set.

## Key findings

- Corroborates the nixCraft guide's recommendation from a second, independent, edited (not just blog) source.
- Explicitly ranks `$-` above the `$PS1`-is-set check, rather than treating them as interchangeable.

## Pros / strengths

- A published, edited technical book is a stronger signal of broad community consensus than any single blog post — two independent sources agreeing on the same preferred test is meaningful corroboration.

## Cons / limitations / caveats

- Older reference material (the Bash Cookbook predates most AI-agent-terminal concerns); it has nothing to say about the automation-vs-human distinction this subject's proposal actually needs.

## Relevance to tai

Corroborating evidence (not new information) for using `$-` over `$PS1` as the proposal's first-line interactivity check.

## Changelog

| Date | Change |
|---|---|
| 2026-10-09 | Initial dossier created. |