bash

Rules for writing reliable Bash shell scripts, including error handling, safe text handling, variable management, and clear structure.

In plain words
What is it for?
Use it when creating or reviewing Bash scripts, especially scripts that run commands, process files, use pipelines, or need predictable failures.
Why use it?
Bash commands can fail silently or behave unexpectedly when values contain spaces or variables are missing. These rules help prevent those scripting mistakes.

Cursor rule

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/sanjeed5/awesome-cursor-rules-mdc/bash
Clone the repo
git clone --depth 1 https://github.com/sanjeed5/awesome-cursor-rules-mdc
Per session 2,750 This file is loaded in full into every session.
When invoked 2,750 The same file — it is already loaded in full.
Security scan D 2 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.

ModelPer sessionOnce invoked
Fable 5 $0.02750 $0.02750
Opus 5 $0.01375 $0.01375
Sonnet 5 $0.00550 $0.00550
Haiku 4.5 $0.00275 $0.00275

Measured 3d ago against content hash cba7244c0dff, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade D, and why

bash scanned grade D with 2 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 3d 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.

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

echo "Sensitive data" | sudo tee /root/protected_file > /dev/null

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

rm -rf "${TMP_DIR}"
rules-mdc/bash.mdc · 427 lines

How it starts

The opening of the file, as written. The whole thing — 427 lines — stays where its author put it; the contents beside it link to each section on GitHub.

bash Best Practices

This guide outlines the definitive best practices for writing bash scripts. Adhere to these rules to ensure your scripts are reliable, readable, and maintainable by the entire team.

1. Code Organization and Structure

1.1 Shebang and Interpreter Options

Always start scripts with #!/usr/bin/env bash for portability. Immediately follow with set -euo pipefail to ensure robust error handling.

  • set -e (errexit): Exit immediately if a command exits with a non-zero status.
  • set -u (nounset): Treat unset variables as an error and exit immediately.
  • set -o pipefail: The return value of a pipeline is the status of the last command to exit with a non-zero status, or zero if all commands exit successfully.

❌ BAD:

#!/bin/bash
# Missing error handling

✅ GOOD:

#!/usr/bin/env bash
set -euo pipefail

# Script logic here

1.2 File Header and Comments

Every script must begin with a descriptive header. Use clear, concise comments for functions and complex logic.

#!/usr/bin/env bash
set -euo pipefail

## my-script.sh
#
# Description: This script performs a critical system backup.
# It backs up configuration files and database dumps to a remote server.
#
# Usage: ./my-script.sh [--full | --incremental]
#
# Globals:
#   BACKUP_DIR
#   REMOTE_HOST
#
# Arguments:
#   --full: Perform a full backup.
#   --incremental: Perform an incremental backup.
#
# Returns:
#   0 on success, non-zero on error.
#
# Author: Your Name <[email protected]>
# Date: 2025-01-01
#
###############################################################################

# ... rest of the script

1.3 Functions and main Entry Point

Encapsulate all script logic within functions. Use a main function as the primary entry point. This improves readability, reusability, and variable scoping.

❌ BAD:

#!/usr/bin/env bash
set -euo pipefail
# Script logic directly in the global scope
echo "Starting operation..."
ls -l /tmp
# ...

Read the full file on GitHub · 427 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.

  1. 3d ago First seen · 427 lines · 0 tokens per session scan D cba7244c0dff

Subscribe to this mod's changes

bash is a cursor rule published in the GitHub repository sanjeed5/awesome-cursor-rules-mdc (3,570 stars, last pushed 3mo ago), licensed CC0-1.0. It adds 2,750 tokens to every session, about $0.0137 per session on Opus 5. A static security scan graded it D with 2 findings (asks for root, recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.