Guidelines for creating and testing shell scripts in a project. They specify where scripts and tests belong, how files should be named, and how the Bach test framework is used.

Use them to add executable scripts, write Bach tests, define test and assertion functions, and run the complete script test suite.

They give shell scripts a consistent layout and a repeatable way to check their behavior.

script — Cursor rule by nerds-odd-e

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add rules/nerds-odd-e/doughnut/script

Clone the repo

git clone --depth 1 https://github.com/nerds-odd-e/doughnut

Made for: Cursor.

Per session 7 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 542 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5	$0.00007	$0.00542
Opus 5	$0.00003	$0.00271
Sonnet 5	$0.00001	$0.00108
Haiku 4.5	$0.00001	$0.00054

Measured 2d ago against content hash 9c0e88039a4b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

script scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/script.mdc · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Shell Script Development

Script Location

Place scripts in the scripts/ directory
Use descriptive names with .sh extension
Make scripts executable: chmod +x scripts/script_name.sh

Unit Testing

Test Framework

Use Bach testing framework for shell script unit tests
Bach is located at scripts/test/vendor/bach.sh
Bach requires Bash 4.3+ (available in nix environment)

Test File Structure

Test files should be in scripts/test/ directory
Use .test extension (e.g., scripts/test/run.sh.test)
Test files must be executable

Writing Tests

Source Bach framework:

source "$(dirname "$0")/vendor/bach.sh"

Create test functions with test- prefix:

test-my-feature() {
    # Test implementation
}

Create assertion functions with -assert suffix:

test-my-feature-assert() {
    @out "expected output"
}

Bach uses dry-run testing - it compares commands executed in test functions with expected commands in assert functions

Running Tests

Run all tests: bash scripts/test/run_all_script_tests.sh
Run individual test: bash scripts/test/script_name.test
In nix environment: ./scripts/run.sh bash scripts/test/run_all_script_tests.sh

Test Requirements

All scripts in scripts/ should have corresponding tests in scripts/test/
Tests are automatically discovered and run in CI
Tests must pass before merging

CURSOR_DEV Mode Behavior

When scripts are run with CURSOR_DEV=true nix develop -c <command>, the nix shell hook (scripts/nix_shell_hook.sh) should:

Output only a one-liner: <<running within nix env>> at the beginning
Suppress all other output: No log messages, environment info, or setup messages should appear
Preserve command output: The actual command's stdout/stderr should be displayed normally
Show errors only: If something goes wrong during setup, errors should still be visible

This ensures that when running commands via CURSOR_DEV=true nix develop -c, users see only:

The one-liner <<running within nix env>>
The command's actual output

Read the full file on GitHub · 76 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2d ago First seen · 76 lines · 7 tokens per session scan A 9c0e88039a4b

Subscribe to this mod's changes

script is a cursor rule published in the GitHub repository nerds-odd-e/doughnut (49 stars, last pushed 2d ago), licensed MIT. It adds 7 tokens to every session and 542 once invoked, about $0.0000 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Testing

script

Getting it into your agent

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

Shell Script Development

Script Location

Unit Testing

Test Framework

Test File Structure

Writing Tests

Running Tests

Test Requirements

CURSOR_DEV Mode Behavior

What this file has done since we first saw it

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