bash-defensive-patterns

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