shell-script-quality

version	1.0.0
name	shell-script-quality
description	Write safe, portable shell scripts. Activate for bash/sh authoring, ShellCheck fixes, BATS test writing, and shell security patterns.
category	quality
allowed-tools	Read Write Edit Grep Glob
license	MIT

Shell Script Quality

Write safe, portable shell scripts. Focus on patterns, pitfalls, and security —not on running checks (the quality gate already handles that).

Quick Start

1. Lint with ShellCheck
2. Fix reported issues
3. Write BATS tests
4. Verify tests pass

Core Workflow

Lint with ShellCheck

# Lint single file
shellcheck script.sh

# Lint all scripts
find scripts -name "*.sh" -exec shellcheck {} +

Common Fixes

• SC2086: Quote variables: "$var" not $var
• SC2155: Separate declaration and assignment
• SC2181: Check exit code directly with if ! command

Write BATS Tests

#!/usr/bin/env bats

setup() {
    source "$BATS_TEST_DIRNAME/../scripts/example.sh"
}

@test "function succeeds with valid input" {
    run example_function "test"
    [ "$status" -eq 0 ]
    [ -n "$output" ]
}

Run Tests

bats tests/

Script Template

#!/bin/bash
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

error_exit() {
    echo "ERROR: $1" >&2
    exit "${2:-1}"
}

main() {
    [[ $# -lt 1 ]] && {
        echo "Usage: $0 <argument>" >&2
        exit 1
    }
}

if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    main "$@"
fi

Configuration

.shellcheckrc in project root:

shell=bash
disable=SC1090
enable=all
source-path=SCRIPTDIR

Validation Loop Pattern

1. Make changes to script
2. Validate immediately: shellcheck script.sh
3. If validation fails: fix and retry
4. Only proceed when validation passes
5. Run tests: bats tests/script.bats