shellcheck-configuration

# ShellCheck Configuration and Static Analysis

Comprehensive guidance for configuring and using ShellCheck to improve shell script quality, catch common pitfalls, and enforce best practices through static code analysis.

## When to Use This Skill

- Setting up linting for shell scripts in CI/CD pipelines
- Analyzing existing shell scripts for issues
- Understanding ShellCheck error codes and warnings
- Configuring ShellCheck for specific project requirements
- Integrating ShellCheck into development workflows
- Suppressing false positives and configuring rule sets
- Enforcing consistent code quality standards
- Migrating scripts to meet quality gates

## ShellCheck Fundamentals

### What is ShellCheck?

ShellCheck is a static analysis tool that analyzes shell scripts and detects problematic patterns. It supports:
- Bash, sh, dash, ksh, and other POSIX shells
- Over 100 different warnings and errors
- Configuration for target shell and flags
- Integration with editors and CI/CD systems

### Installation

```bash
# macOS with Homebrew
brew install shellcheck

# Ubuntu/Debian
apt-get install shellcheck

# From source
git clone https://github.com/koalaman/shellcheck.git
cd shellcheck
make build
make install

# Verify installation
shellcheck --version
```

## Configuration Files

### .shellcheckrc (Project Level)

Create `.shellcheckrc` in your project root:

```
# Specify target shell
shell=bash

# Enable optional checks
enable=avoid-nullary-conditions
enable=require-variable-braces

# Disable specific warnings
disable=SC1091
disable=SC2086
```

### Environment Variables

```bash
# Set default shell target
export SHELLCHECK_SHELL=bash

# Enable strict mode
export SHELLCHECK_STRICT=true

# Specify configuration file location
export SHELLCHECK_CONFIG=~/.shellcheckrc
```

## Common ShellCheck Error Codes

### SC1000-1099: Parser Errors
```bash
# SC1004: Backslash continuation not followed by newline
echo hello\
world  # Error - needs line continuation

# SC1008: Invalid d