Run RuboCop Linter

Execute RuboCop static analysis with intelligent defaults.

Arguments

The user may provide:

• No argument: Lint changed files or entire project
• File/directory path: Lint specific files
• --fix: Auto-correct safe violations
• --fix-all: Auto-correct all violations (including unsafe)

Execution Strategy

Check for RuboCop

# Verify RuboCop is available
bundle info rubocop 2>/dev/null || gem list rubocop

Lint Specific Files

bundle exec rubocop path/to/file.rb
bundle exec rubocop app/models/

Lint Changed Files Only

# Git diff files
bundle exec rubocop $(git diff --name-only --diff-filter=d HEAD | grep '\.rb$')

# Or staged files
bundle exec rubocop $(git diff --cached --name-only --diff-filter=d | grep '\.rb$')

Auto-correct

# Safe auto-correct
bundle exec rubocop -a path/to/file.rb

# Unsafe auto-correct (may change behavior)
bundle exec rubocop -A path/to/file.rb

# Auto-correct with specific cops
bundle exec rubocop --only Style/StringLiterals -a

Useful Options

# Show only offenses (no file names)
bundle exec rubocop --format simple

# Show offense counts by cop
bundle exec rubocop --format offenses

# Generate TODO file for gradual adoption
bundle exec rubocop --auto-gen-config

# Check specific cops
bundle exec rubocop --only Layout,Style/StringLiterals

# Exclude specific cops
bundle exec rubocop --except Metrics/MethodLength

Output Handling

• Use --format progress for quick overview
• Use --format clang for IDE-friendly output with context
• Show cop names with -D for easier lookup
• Use --parallel for faster execution on large codebases

Common Configurations

Rails Omakase (rails/rubocop-rails-omakase)

# If using Rails Omakase
bundle exec rubocop -c .rubocop.yml

Standard Ruby

# If using standardrb
bundle exec standardrb
bundle exec standardrb --fix

Error Categories

Explain violation categories when showing results:

• Layout: Formatting, indentation, whitespace
• Lint: Potential bugs, ambiguous code
• Metrics: Complexity, length limits
• Naming: Variable/method naming conventions
• Style: Idiomatic Ruby style preferences
• Security: Potential security issues

Examples

/ruby:lint                          # Lint entire project
/ruby:lint app/models/user.rb       # Lint specific file
/ruby:lint lib/ --fix               # Auto-fix safe issues in lib/
/ruby:lint --fix-all                # Auto-fix all issues (careful!)