Shell Style Guide

Shell Style Guide

Quick Start

Apply these requirements for any shell work:

1. ShellCheck must pass with zero errors.
2. Format with shfmt based on shell type.
3. Use braces for variable expansion (${var}).
4. Keep scripts/lib*.sh POSIX sh compatible.

Commands

• Bash file:
  • shfmt -i 4 -ci -bn -sr -w <file>
  • shellcheck -s bash <file>
• POSIX sh file:
  • shfmt -p -i 4 -ci -bn -sr -w <file>
  • shellcheck -s sh <file>
• Library file:
  • shfmt -p -i 4 -ci -bn -sr -w scripts/lib_example.sh
  • shellcheck -s sh -x scripts/lib_example.sh

Core Rules

• Use #!/bin/bash for executables unless strict POSIX compatibility is required.
• Use #!/bin/sh for scripts/lib*.sh.
• Do not use Bash-only features in POSIX sh (local, arrays, [[ ]], process substitution).
• Quote expansions and use explicit error handling (set -euo pipefail for Bash, set -eu for POSIX).
• For POSIX sh helper variables in non-library scripts, use single underscore namespacing.

Detailed Reference

For the complete Tracee shell style details, see reference.md.