# Google Shell Style Detailed

> Comprehensive Google Shell style rules with section-level guidance. Use when google-shell-style is insufficient, for thorough reviews, or when the user names this skill.

- Skill: `peterish8/google-shell-style-detailed` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add peterish8/google-shell-style-detailed`
- Raw SKILL.md: https://api.skillmd.com/api/skills/peterish8/google-shell-style-detailed/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: peterish8 (https://skillmd.com/u/peterish8)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/peterish8/google-shell-style-detailed

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# Google Shell Style (Detailed)

Source: [https://google.github.io/styleguide/shellguide.html](https://google.github.io/styleguide/shellguide.html)

Pair with the quick reference: [google-shell-style](../google-shell-style/SKILL.md)

This skill expands the short skill with section-level rules from Google's guide.
For authoritative full text, see the official URL and [reference.md](reference.md).

## How to use

1. Start from [google-shell-style](../google-shell-style/SKILL.md) for everyday edits
2. Use this skill for reviews, ambiguous cases, or API/doc conventions
3. Consult [reference.md](reference.md) for source paths and supplemental docs

## Section rules

#### When to use Shell

- If you're mostly calling other utilities and are doing relatively little
- If performance matters, use something other than shell.
- If you are writing a script that is more than 100 lines long, or that uses
- When assessing the complexity of your code (e.g. to decide whether to switch
#### File Extensions

- If the executable will have a build rule that renames the source file
- If the executable will be added directly to the user's PATH, then prefer
- If neither of the above apply, then either choice is acceptable.
#### Function Comments

- Description of the function.
- Globals: List of global variables used and modified.
- Arguments: Arguments taken.
- Outputs: Output to STDOUT or STDERR.
- Returns: Returned values other than the default exit status of the last
#### Case statement

- Indent alternatives by 2 spaces.
- A one-line alternative needs a space after the close parenthesis of the
- Long or multi-command alternatives should be split over multiple lines with
#### Variable expansion

- Stay consistent with what you find for existing code.
- Quote variables, see Quoting section below.
- Don't brace-delimit single character shell specials / positional parameters,
#### Quoting

- Always quote strings containing variables, command substitutions, spaces or
- Use arrays for safe quoting of lists of elements, especially command-line
- Optionally quote shell-internal, readonly
- Prefer quoting strings that are "words" (as opposed to command options or
- Be aware of the quoting rules for pattern matches in [[ … ]]. See the
- Use "$@" unless you have a specific reason to use $*, such as simply
#### Arrays Pros

- Using Arrays allows lists of things without confusing quoting semantics.
- Arrays make it possible to safely store sequences/lists of arbitrary
#### Arithmetic

- particularly with set -e enabled. For example,