Shell/Bash Guide

Applies to: Bash 4+, POSIX sh, Automation Scripts, CI/CD Pipelines, Makefiles

Core Principles

1. Strict Mode Always: Every script starts with set -euo pipefail to fail fast on errors
2. Quote Everything: All variable expansions must be double-quoted to prevent word splitting and globbing
3. Explicit Over Implicit: Use [[ ]] for conditionals, local for function variables, named constants for magic values
4. Fail Loudly: Never swallow errors silently; use trap for cleanup and meaningful exit codes
5. ShellCheck Clean: All scripts pass shellcheck with zero warnings before commit

Guardrails

Shebang and Strict Mode

• Every script: #!/usr/bin/env bash (or #!/bin/sh for POSIX)
• Immediately follow with set -euo pipefail
• Use set -x only for debugging, never in production scripts