bash-shell-scripting

bash-shell-scripting is a skill for Claude Code, Codex from d-padmanabhan/agent-engineering-handbook. It costs 69 tokens per session (2,421 once invoked), scanned A, original, MIT.

A set of practices for writing reliable Bash shell scripts, command-line tools, and Makefiles.

In plain words
What is it for?
Writing or reviewing shell scripts, Makefiles, argument parsing, cleanup logic, and shell linting.
Why use it?
It helps prevent silent script failures, portability problems, unsafe error handling, and hard-to-maintain shell code.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

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 skills/d-padmanabhan/agent-engineering-handbook/bash-shell-scripting
Any agent
npx skills add d-padmanabhan/agent-engineering-handbook --skill bash-shell-scripting
Clone the repo
git clone --depth 1 https://github.com/d-padmanabhan/agent-engineering-handbook

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for bash-shell-scripting

README.md
[![agentmods](https://agentmods.dev/badge/skills/d-padmanabhan/agent-engineering-handbook/bash-shell-scripting.svg)](https://agentmods.dev/skills/d-padmanabhan/agent-engineering-handbook/bash-shell-scripting)
Your own site
<a href="https://agentmods.dev/skills/d-padmanabhan/agent-engineering-handbook/bash-shell-scripting"><img src="https://agentmods.dev/badge/skills/d-padmanabhan/agent-engineering-handbook/bash-shell-scripting.svg" alt="Measured on agentmods" height="20"></a>
Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,421 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 5.1 $0.00069 $0.02421
Opus 5 $0.00034 $0.01210
Sonnet 5 $0.00014 $0.00484
Haiku 4.5 $0.00007 $0.00242

Measured 2d ago against content hash e3744feebada, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

bash-shell-scripting scanned grade A with 1 finding 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

require_command curl
skills/bash-shell-scripting/SKILL.md · 347 lines

How it starts

The opening of the file, as written. The whole thing — 347 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Bash & Shell Scripting

Mandatory gates are owned by the Bash rule (${HANDBOOK_ROOT}/rules/140-bash.mdc). This skill owns procedures and examples.

Core Principles

  • DRY: Don't Repeat Yourself
  • KISS: Keep It Simple
  • Fail Fast: Exit on errors immediately
  • Zero Warnings: Must pass shellcheck

Quick Reference

set -euo pipefail           # Strict mode (fail-fast)
set -uo pipefail            # Controlled mode (explicit error handling)
set -Euo pipefail           # Strict + ERR trap propagation
command -v cmd >/dev/null   # Check if command exists (portable)
trap 'cleanup' EXIT         # Always cleanup
flock -n 200 || exit 1      # Prevent concurrent runs
readonly VAR="value"        # Immutable constant
local var="value"           # Function-local variable

Core Standards

Aspect Standard
Shebang #!/usr/bin/env bash or #!/bin/bash
Safety Mode set -euo pipefail (strict) or set -uo pipefail (controlled)
Linting Must pass shellcheck with 0 errors/warnings
Formatting Must pass shfmt -i 2 -ci -sr -bn; prefer ~100-character lines
Extension .sh for scripts
Variables Uppercase constants/globals, lowercase locals, descriptive names, braces + quotes ("${VAR}")

Generation Contract

For any non-trivial script (more than 10-15 lines, more than one command phase, argument parsing, dependency checks, config resolution, build/deploy/verify steps), generate this structure:

  1. Header block.
  2. Commented debug toggle (# set -x), disabled by default.
  3. Strict or controlled mode.
  4. Readonly constants and timestamped LOGFILE.
  5. logmsg, die, and optional debug helper.
  6. require_command for dependencies.
  7. Helper functions with lowercase locals.
  8. parse_args.
  9. main().
  10. main "$@" as the final line.

Reject generated Bash that skips this structure unless the script is intentionally tiny and linear.

Error Handling Modes

Read the full file on GitHub · 347 lines

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 347 lines · 69 tokens per session scan A e3744feebada

Subscribe to this mod's changes

bash-shell-scripting is a skill published in the GitHub repository d-padmanabhan/agent-engineering-handbook (16 stars, last pushed 6d ago), licensed MIT. It adds 69 tokens to every session and 2,421 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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