# Write Bash Scripts

> Applies Bash style conventions when creating or editing Bash scripts. Use when: (1) creating new Bash scripts, (2) editing existing scripts in /bin/, or (3) reviewing Bash code for bugs or style issues.

- Skill: `cboone/write-bash-scripts` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add cboone/write-bash-scripts`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cboone/write-bash-scripts/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cboone (https://skillmd.com/u/cboone)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cboone/write-bash-scripts

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# Bash Style Guide

Apply the Bash conventions from `./references/BASH.md` when creating or editing Bash scripts.

## Key Conventions

Read `./references/BASH.md` for the complete guide. Summary:

### Script Structure

- Shebang: `#!/usr/bin/env bash`
- Strict mode: `set -euo pipefail`
- Main function called at end: `main "${@}"`

### Naming

- Functions: `snake_case`
- Local variables: `lower_case`
- Constants: `ALL_CAPS` with `readonly`

### Syntax

- Variable expansion: `${var}` not `$var`
- Command substitution: `$(...)` not backticks
- Tests: `[[...]]` not `[...]`
- Function syntax: `function name() { }` with both keyword and parentheses

### Quoting

- Always quote variable expansions: `"${var}"`
- Always quote command substitutions: `"$(cmd)"`
- Use arrays for lists, not word splitting

### Local Variables

- Declare with `local`
- Separate declaration from command substitution to preserve exit codes

## Validation

Whenever possible, validate the script before finishing. Prefer using a project-specific validation script, if available. Common locations include declarations in `package.json` and scripts stored in `bin/`. If those aren't present, `shellcheck` is a commonly available linter for Bash scripts.