bash-defensive-patterns by wshobson

Decision brief

What it does—and where it fits

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.

Best for

Writing production automation scripts
Building CI/CD pipeline scripts
Creating system administration utilities

Not for

Tasks that require unconfirmed production actions or broad system permissions.
Environments where the pinned source and install steps cannot be inspected.

Compatibility matrix

Platform support, with evidence labels

Platform	Status	Evidence	What to check
Codex	Not declared	No explicit evidence	Portability before use
Claude Code	Not declared	No explicit evidence	Portability before use
Cursor	Not declared	No explicit evidence	Portability before use
Gemini CLI	Not declared	No explicit evidence	Portability before use

Open the compatibility checker

Installation

Inspect first. Install second.

The source command is displayed only when detected. A safe inspection prompt is always available so your agent can explain every action before execution.

Source-detected install commandSource

npx skills add https://github.com/wshobson/agents --skill "plugins/shell-scripting/skills/bash-defensive-patterns"

Safe inspection promptEditorial

Inspect the Agent Skill "bash-defensive-patterns" from https://github.com/wshobson/agents/blob/c4b82b0ad771190355eb8e204b1329732a18449a/plugins/shell-scripting/skills/bash-defensive-patterns/SKILL.md at commit c4b82b0ad771190355eb8e204b1329732a18449a. List every install step, command, network request, credential, file read/write, external action, and rollback step. Explain whether it fits my task. Do not install or execute anything until I approve.

Workflow

What the source asks the agent to do

01
When to Use This Skill
Writing production automation scripts
Writing production automation scriptsBuilding CI/CD pipeline scriptsCreating system administration utilities
02
Detailed patterns and worked examples
Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.
Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.
03
Best Practices Summary
1. Always use strict mode - set -Eeuo pipefail 2. Quote all variables - "$variable" prevents word splitting 3. Use [[]] conditionals - More robust than [ ] 4. Implement error trapping - Catch and handle errors gracefully 5. Validate all inputs - Check file existence, permissions…
Always use strict mode - set -Eeuo pipefailQuote all variables - "$variable" prevents word splittingUse [[]] conditionals - More robust than [ ]

Permission review

Static risk signals and limitations

Reads files

low · line 18

The documentation asks the agent to read local files, directories, or repositories.

Detailed pattern documentation lives in `references/details.md`. Read that file when the navigation tier above is insufficient.

Evidence record

Why each signal appears

EvidenceSourceComputedTestedEditorial

Signal	Value	Evidence type	Meaning
Quality score	79/100	Computed	Documentation, specificity, maintenance, and trust rules
Repository stars	38,313	Source	Repository attention, not individual Skill quality
Compatibility	0 platforms	Source	Declared in the catalog source record
Usage guide	automated source guide	Editorial	Generated or reviewed according to the visible evidence level

Pinned source

Provenance and original SKILL.md

Repository: wshobson/agents
Skill path: plugins/shell-scripting/skills/bash-defensive-patterns/SKILL.md
Commit: c4b82b0ad771190355eb8e204b1329732a18449a
License: MIT
Collected: 2026-07-28
Default branch: main

View the original SKILL.md

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 than which for checking executables
Prefer printf over echo - More predictable across systems