bash-patternslisted

# Bash patterns - Default assumption: bash 5.x targeting macOS (via Homebrew bash) and Linux. - Scripts use `#!/usr/bin/env bash`, so the resolved binary is whatever is first on PATH -- on the user's machine that's the Homebrew 5.x build, not the stock macOS `/bin/bash` 3.2. - Anything that requires bash 4.0+ (case modification, `mapfile`, `${parameter@op}`) is unsafe under stock macOS bash; flagged here when the version cut matters. ## Severity rubric Severity rubric: matches `rules/markdown-report.md` (failure/warning/info). ## Reference files | File | Covers | | -------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------ | | [reference/safety-flags.md](reference/safety-flags.md) | Script preamble, `set -euo pipefail` edge cases, `inherit_errexit`, `nullglob`, verification before shipping | | [reference/quoting.md](reference/quoting.md) | Quoting rules, nested quoting, heredoc indentation, `printf` over `echo`, zsh-vs-bash differences | | [reference/conditionals.md](reference/conditionals.md) | `[[ ]]` over `[ ]`, glob vs literal, numeric vs string comparison, `(( ))`, `case` | | [reference/functions-