Claude Code Tutorial 2026: Complete Developer Guide

Introduction

Claude Code is Anthropic's official CLI tool that brings Claude's capabilities directly into your development workflow. This comprehensive guide covers everything from installation to advanced usage patterns.

Installation & Setup

System Requirements

• Node.js: 18.0.0 or higher

• npm: 9.0.0 or higher

• Operating Systems: macOS, Linux, Windows (WSL2)

• Terminal: Any modern terminal with Unicode support

Quick Install

bash
npm install -g @anthropic-ai/claude-code
claude-code --version


Authentication Setup

1. Get API Key: Visit console.anthropic.com
2. Configure CLI:
   ```bash
   claude-code config set api-key YOUR_API_KEY
   ```
3. Verify Connection:
   ```bash
   claude-code test
   ```

Basic Usage

Interactive Chat Mode

bash
claude-code chat


Features:
Persistent conversation history
Automatic code syntax highlighting
Copy code blocks with one keystroke
Multi-line input support
Single Command Mode

bash
claude-code ask "Explain async/await in JavaScript"


Perfect for:
Quick questions
Scripting and automation
CI/CD integration
File Context

bash
claude-code ask "Review this code" --file src/app.ts
claude-code ask "Find bugs" --files "src/**/*.ts"


Claude analyzes files before responding with full context.

Advanced Features

Code Generation

bash
claude-code generate "React form component with validation" --output components/Form.tsx


Options:
`--language`: Specify programming language
`--style`: Code style (typescript, javascript, etc.)
`--framework`: Target framework
Code Refactoring

bash
claude-code refactor src/legacy.js --prompt "Convert to TypeScript with type safety"


Automatically:
Backs up original file
Applies refactoring
Validates syntax
Shows diff
Code Review

bash
claude-code review --files "src/**/*.ts" --output review.md


Generates:
Security vulnerabilities
Performance issues
Code quality suggestions
Best practice violations
Debugging Assistant

bash
claude-code debug --error "TypeError: Cannot read property 'map' of undefined" --context src/app.ts


Claude analyzes:
Error message
Stack trace
Surrounding code
Common causes and fixes
Configuration & Customization

Config File Location

macOS/Linux: `~/.claude-code/config.json`
Windows: `%USERPROFILE%\.claude-code\config.json`
Custom Settings

json
{
  "model": "claude-sonnet-4-5",
  "temperature": 0.7,
  "maxTokens": 4096,
  "streaming": true,
  "theme": "dark",
  "codeStyle": "prettier"
}


Model Selection

bash
claude-code config set model claude-opus-4-5
claude-code config set model claude-sonnet-4-5
claude-code config set model claude-haiku-4-5


Recommendations:
Opus: Complex architecture, critical code
Sonnet: Daily development (best balance)
Haiku: Quick questions, high volume
Project Integration

Initialize Project

bash
cd your-project
claude-code init


Creates `.claude/` directory with:
Project-specific prompts
Custom commands
Ignore patterns
Custom Commands

Create `.claude/commands/`:

yaml
# .claude/commands/test.yaml
name: test
description: Run tests and analyze failures
command: |
  Run all tests in the project.
  If any fail, analyze the failure and suggest fixes.


Usage: `claude-code test`

Git Integration

bash
claude-code commit


Automatically:
Analyzes staged changes
Generates commit message
Follows conventional commits
Asks for confirmation
Keyboard Shortcuts

Interactive Mode:
`Ctrl+C`: Cancel current input
`Ctrl+D`: Exit chat
`Ctrl+L`: Clear screen
`Ctrl+R`: Search history
`Tab`: Autocomplete commands
Code Blocks:
`Ctrl+Shift+C`: Copy code block
`Ctrl+Shift+S`: Save code block to file
Best Practices

Effective Prompting

Bad:
bash
claude-code ask "fix bug"


Good:
bash
claude-code ask "This React component re-renders unnecessarily. Analyze and optimize using React.memo or useMemo" --file components/List.tsx


Key principles:
Be specific about the problem
Provide relevant context
Specify desired outcome
Include files when applicable
Performance Optimization

Cache frequently used prompts:
bash
claude-code config set cache-prompts true


Reduce token usage:
bash
claude-code ask "summarize changes" --files "src/**/*.ts" --max-tokens 1000


Use appropriate models:
Haiku for simple queries (10x cheaper)
Sonnet for most tasks (best value)
Opus only when quality critical
Security Considerations

Never include:
API keys or credentials
Personal identifiable information (PII)
Proprietary business logic (if using API)
Configure ignore patterns:

# .claude/ignore
.env
*.key
secrets/
credentials.json


Troubleshooting

Common Issues

"API key not found"
bash
claude-code config get api-key
claude-code config set api-key YOUR_KEY


"Rate limit exceeded"
Wait 60 seconds or upgrade plan. Check usage:
bash
claude-code usage


"Context too large"
Reduce files or use `--max-files` option:
bash
claude-code ask "analyze" --files "src/**/*.ts" --max-files 10


Debug Mode

bash
claude-code --debug ask "test"


Shows:
API requests/responses
Token usage
Timing information
Error details
Advanced Workflows

Code Generation Pipeline

bash
# Generate component
claude-code generate "User profile card" --output components/UserCard.tsx

# Generate tests
claude-code generate "Tests for UserCard" --file components/UserCard.tsx --output components/UserCard.test.tsx

# Review both
claude-code review --files "components/UserCard.*"


Automated Documentation

bash
# Generate API docs
claude-code ask "Generate API documentation" --files "src/api/**/*.ts" --output docs/API.md

# Update README
claude-code ask "Update README with new features" --file README.md --in-place


CI/CD Integration

yaml
# .github/workflows/claude-review.yml
name: Claude Code Review
on: [pull_request]
jobs:
  review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - run: npm install -g @anthropic-ai/claude-code
      - run: claude-code review --files "src/**/*.ts" --output review.md
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
      - uses: actions/upload-artifact@v3
        with:
          name: code-review
          path: review.md


Pricing & Usage Tracking

Check Usage

bash
claude-code usage
claude-code usage --month 2026-02


Estimate Costs

bash
claude-code estimate --files "src/**/*.ts" --prompt "Review code"


Shows estimated tokens and cost before execution.

Cost Optimization

Monthly cost examples:
Light usage (100 queries/month, Sonnet): ~$5-10
Medium usage (500 queries/month, Sonnet): ~$25-40
Heavy usage (2000 queries/month, Sonnet): ~$100-150
Tips:
Use Haiku for simple questions
Cache responses locally when possible
Limit file context to relevant files only
Conclusion

Claude Code CLI transforms AI from a web tool to an integrated development assistant. Key takeaways:

1. Start simple: Begin with `claude-code chat` for interactive exploration
2. Add context: Use `--file` flags for better responses
3. Customize: Create project-specific commands and configurations
4. Integrate: Build Claude into your daily workflow
5. Optimize: Choose appropriate models and manage costs

Next steps:
Install Claude Code: `npm install -g @anthropic-ai/claude-code`
Complete the interactive tutorial: `claude-code tutorial`
Join the community: github.com/anthropics/claude-code
Read the docs: docs.anthropic.com/claude-code
The future of development isn't writing code alone—it's collaborating with AI assistants that understand your entire codebase and development context. Claude Code makes that future available today.