bash-pro

Use this skill when

• Writing or reviewing Bash scripts for automation, CI/CD, or ops
• Hardening shell scripts for safety and portability

Do not use this skill when

• You need POSIX-only shell without Bash features
• The task requires a higher-level language for complex logic
• You need Windows-native scripting (PowerShell)

Instructions

1. Define script inputs, outputs, and failure modes.
2. Apply strict mode and safe argument parsing.
3. Implement core logic with defensive patterns.
4. Add tests and linting with Bats and ShellCheck.

Safety

• Treat input as untrusted; avoid eval and unsafe globbing.
• Prefer dry-run modes before destructive actions.

Focus Areas

• Defensive programming with strict error handling
• POSIX compliance and cross-platform portability
• Safe argument parsing and input validation
• Robust file operations and temporary resource management
• Process orchestration and pipeline safety
• Production-grade logging and error reporting
• Comprehensive testing with Bats framework
• Static analysis with ShellCheck and formatting with shfmt
• Modern Bash 5.x features and best practices
• CI/CD integration and automation workflows

Approach

• Always use strict mode with set -Eeuo pipefail and proper error trapping
• Quote all variable expansions to prevent word splitting and globbing issues
• Prefer arrays and proper iteration over unsafe patterns like for f in $(ls)
• Use [[ ]] for Bash conditionals, fall back to [ ] for POSIX compliance
• Implement comprehensive argument parsing with getopts and usage functions
• Create temporary files and directories safely with mktemp and cleanup traps
• Prefer printf over echo for predictable output formatting
• Use command substitution $() instead of backticks for readability
• Implement structured logging with timestamps and configurable verbosity
• Design scripts to be idempotent and support dry-run modes
• Use shopt -s inherit_errexit for better error propagation in Bash 4.4+
• Employ IFS=$'\n\t' to prevent unwanted word splitting on spaces
• Validate inputs with : "${VAR:?message}" for required environment variables
• End option parsing with -- and use rm -rf -- "$dir" for safe operations
• Support --trace mode with set -x opt-in for detailed debugging
• Use xargs -0 with NUL boundaries for safe subprocess orchestration
• Employ readarray/mapfile for safe array population from command output
• Implement robust script directory detection: SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"
• Use NUL-safe patterns: find -print0 | while IFS= read -r -d '' file; do ...; done