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.
npx agentmods add skills/martineserios/thebrana/bash-defensive-patternsnpx skills add martineserios/thebrana --skill bash-defensive-patternsgit clone --depth 1 https://github.com/martineserios/thebranaWrote 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.
[](https://agentmods.dev/skills/martineserios/thebrana/bash-defensive-patterns)<a href="https://agentmods.dev/skills/martineserios/thebrana/bash-defensive-patterns"><img src="https://agentmods.dev/badge/skills/martineserios/thebrana/bash-defensive-patterns.svg" alt="Measured on agentmods" height="20"></a>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 5.1 | $0.00036 | $0.00480 |
| Opus 5 | $0.00018 | $0.00240 |
| Sonnet 5 | $0.00007 | $0.00096 |
| Haiku 4.5 | $0.00004 | $0.00048 |
Grade A, and why
bash-defensive-patterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Bash Defensive Patterns
Comprehensive guidance for writing production-ready Bash scripts using defensive programming techniques, error handling, and safety best practices to prevent common pitfalls and ensure reliability.
When to Use This Skill
- Writing production automation scripts
- Building CI/CD pipeline scripts
- Creating system administration utilities
- Developing error-resilient deployment automation
- Writing scripts that must handle edge cases safely
- Building maintainable shell script libraries
- Implementing comprehensive logging and monitoring
- Creating scripts that must work across different platforms
Detailed patterns and worked examples
Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.
Best Practices Summary
- Always use strict mode -
set -Eeuo pipefail - Quote all variables -
"$variable"prevents word splitting - Use [[]] conditionals - More robust than [ ]
- Implement error trapping - Catch and handle errors gracefully
- Validate all inputs - Check file existence, permissions, formats
- Use functions for reusability - Prefix with meaningful names
- Implement structured logging - Include timestamps and levels
- Support dry-run mode - Allow users to preview changes
- Handle temporary files safely - Use mktemp, cleanup with trap
- Design for idempotency - Scripts should be safe to rerun
- Document requirements - List dependencies and minimum versions
- Test error paths - Ensure error handling works correctly
- Use
command -v- Safer thanwhichfor checking executables - Prefer printf over echo - More predictable across systems
What ships with it
1 file 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.
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.
- 6d ago First seen · 48 lines · 36 tokens per session scan A f82f5c9c7ecf
bash-defensive-patterns is a skill published in the GitHub repository martineserios/thebrana (3 stars, last pushed yesterday), licensed MIT. It adds 36 tokens to every session and 480 once invoked, about $0.0002 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 2026-08-31.
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