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