Installing Claude Code

Getting Claude Code Running on Your Machine

This lesson covers everything you need to install, authenticate, and verify Claude Code across all supported platforms.

System Requirements

Installation

Claude Code is installed as a global npm package:

# Install Claude Code globally
npm install -g @anthropic-ai/claude-code

# Verify installation
claude --version

Authentication

Claude Code supports two authentication methods:

Option 1: Claude Pro/Team Subscription (Recommended for Learning)

# Launch Claude Code — it will prompt you to authenticate
claude

# Select "Claude.ai login" from the auth menu
# A browser window opens, log in with your Claude account
# Return to terminal — you're authenticated

Option 2: Anthropic API Key (Recommended for Production)

# Set your API key as an environment variable
export ANTHROPIC_API_KEY="sk-ant-..."

# Or add to your shell profile for persistence
echo 'export ANTHROPIC_API_KEY="sk-ant-..."' >> ~/.zshrc
source ~/.zshrc

# Launch Claude Code
claude

Option 3: AWS Bedrock / Google Vertex AI

For enterprise use, Claude Code supports routing through cloud providers:

# AWS Bedrock
export CLAUDE_CODE_USE_BEDROCK=1
export AWS_REGION="us-east-1"
claude

# Google Vertex AI
export CLAUDE_CODE_USE_VERTEX=1
export CLOUD_ML_REGION="us-east1"
claude

First Launch

cd /path/to/your/project
claude

On first launch:

1. Claude Code scans your project directory
2. Loads any existing CLAUDE.md files
3. Shows the interactive terminal UI
4. Ready for your first prompt

Platform-Specific Notes

macOS

Works out of the box. If you use Homebrew's Node.js, ensure the global bin is in your PATH:

npm config get prefix  # Should be /usr/local or similar
echo $PATH             # Verify the bin directory is included

Linux (Ubuntu/Debian)

# If using nvm, ensure the correct Node version is active
nvm use 20
npm install -g @anthropic-ai/claude-code

Windows (WSL2)

Claude Code runs in WSL2 (Windows Subsystem for Linux):

# In WSL2 terminal
sudo apt update && sudo apt install nodejs npm
npm install -g @anthropic-ai/claude-code

Note: Claude Code does not natively support Windows CMD or PowerShell. Use WSL2.

Updating Claude Code

# Update to the latest version
npm update -g @anthropic-ai/claude-code

# Check for updates
claude --version
npm view @anthropic-ai/claude-code version

Troubleshooting Common Installation Issues

"command not found: claude" The npm global bin directory is not in your PATH.

npm config get prefix
# Add <prefix>/bin to your PATH

"EACCES permission denied"

# Fix npm permissions
sudo chown -R $(whoami) $(npm config get prefix)/{lib/node_modules,bin,share}

Authentication timeout Ensure your system clock is synchronized:

# macOS/Linux
date
# If wrong: sudo ntpdate -u pool.ntp.org

You are now ready to use Claude Code. The next lesson covers pricing so you understand how to manage costs as you learn.