Claude Code CLI

Claude Code’s source code appears to have leaked because an early npm release was shipped with source-map data still attached. A developer inspecting the bundled cli.mjs file noticed --enable-source-maps and then found a huge sourceMappingURL block at the bottom, which suggested the package still contained enough mapping data to reconstruct the original source. Anthropic later removed the source map from newer updates, but by then the earlier package had already been downloaded and inspected, so the code could still be recovered from what was already published.

Overview

Claude Code CLI is a sophisticated terminal application that provides an interactive interface for developers to collaborate with Claude (Anthropic's AI assistant) directly from their terminal. It combines the power of large language models with comprehensive file system operations, tool calling, and extensible architecture.

Features

Core Capabilities

Interactive AI Chat - Natural language coding assistance with real-time streaming responses
File Operations - Read, edit, write, search, and analyze files with AI assistance
Bash Execution - Execute shell commands with safety controls and sandboxing
Web Integration - Search and fetch web content directly from the CLI
Agent Swarms - Spawn sub-agents for parallel task execution
Task Management - Track and manage background tasks and operations

Advanced Features

Multiple Execution Modes
- Interactive REPL mode for conversational coding
- Headless mode (-p/--print) for scripting and CI/CD pipelines
- Remote session support via SSH and direct connections
MCP (Model Context Protocol)
- Connect to external tool servers
- Dynamic tool discovery and execution
- Enterprise-grade security with allowlist/denylist policies
Context Management
- Automatic context compaction for long conversations
- Session persistence and resume capability
- Project-specific memory and context
Developer Tools
- Git integration (commit, diff, branch management)
- LSP (Language Server Protocol) support
- Voice mode for speech-to-text input
- Chrome/IDE integration

Installation

Prerequisites

Bun runtime (latest stable version recommended)
Git (for repository operations)

Install Options

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

# Or install via Bun
bun install -g @anthropic-ai/claude-code

# Or use the native installer (macOS/Linux)
curl -fsSL https://claude.ai/install.sh | sh

Post-Installation Setup

# Run the setup wizard
claude

# Or initialize with a specific directory
claude /path/to/your/project

# Authenticate with your Anthropic account
claude login

Quick Start

# Start interactive mode
claude

# Run in headless mode with a prompt
claude -p "Explain this codebase"

# Execute a command and exit
claude -p "Fix the bug in src/utils.ts" --allowedTools BashTool,FileEditTool

# Resume a previous session
claude --resume

Available Commands

Type / in the REPL to see all available commands. Here are the key ones:

Core Commands

Command	Description
`/help`	Show help and available commands
`/exit` or `/quit`	Exit the REPL
`/clear` or `/reset`	Clear conversation history
`/compact`	Summarize conversation to save context
`/init`	Initialize CLAUDE.md file with codebase documentation

Development Commands

Command	Description
`/commit`	Create a git commit
`/review`	Review a pull request
`/diff`	Show git diff interface
`/branch`	Branch management
`/doctor`	Run diagnostics and troubleshooting

Configuration Commands

Command	Description
`/config` or `/settings`	Open configuration panel
`/theme`	Change terminal theme
`/model`	Set the AI model
`/mcp`	Manage MCP servers
`/skills`	List available skills

Context & Memory

Command	Description
`/context`	Visualize current context usage
`/memory`	Edit Claude memory files
`/files`	List tracked files
`/tasks`	List background tasks

Session Management

Command	Description
`/session` or `/remote`	Show remote session URL
`/resume`	Resume previous session
`/share`	Share session
`/cost`	Show session cost and duration

Built-in Tools

Claude Code comes with 40+ built-in tools for file operations, execution, and integration:

File Operations

FileReadTool - Read files, images, PDFs with smart pagination
FileEditTool - Edit files with sed-like functionality
FileWriteTool - Create or overwrite files
GlobTool - Find files using glob patterns
GrepTool - Search file contents with regex
NotebookEditTool - Edit Jupyter notebooks

Execution

BashTool - Execute shell commands with sandboxing
PowerShellTool - Windows PowerShell execution

Web & Search

WebFetchTool - Fetch web pages content
WebSearchTool - Search the web

AI & Agents

AgentTool - Spawn sub-agents for parallel work
TaskCreateTool/TaskStopTool/TaskListTool - Background task management

MCP Integration

MCPTool - Execute tools from MCP servers
ListMcpResourcesTool/ReadMcpResourceTool - MCP resource management

Configuration

Global Configuration (~/.claude.json)

{
  "theme": "dark",
  "autoCompactEnabled": true,
  "editorMode": "vim",
  "verbose": false,
  "mcpServers": {
    "my-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path"]
    }
  }
}

Project Configuration (.claude.json)

{
  "allowedTools": ["BashTool", "FileEditTool", "FileReadTool"],
  "mcpServers": {
    "project-server": {
      "type": "sse",
      "url": "https://api.example.com/mcp"
    }
  }
}

MCP Configuration (.mcp.json)

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "."]
    },
    "github": {
      "type": "sse",
      "url": "https://api.github.com/mcp",
      "oauth": {
        "clientId": "your-client-id"
      }
    }
  }
}

Environment Variables

Variable	Description
`CLAUDE_CODE_DEBUG`	Enable debug logging
`CLAUDE_CONFIG_DIR`	Override config directory
`DISABLE_AUTOUPDATER`	Disable auto-updater
`CLAUDE_CODE_BUBBLEWRAP`	Enable sandbox mode

Usage Examples

Code Review

# Review the current PR
/review

# Security-focused review
/security-review

# Deep bug-finding review
/ultrareview

File Operations

# Read a file with specific range
Please read src/main.ts lines 50-100

# Edit a file
Please update the config in package.json to add a new script

# Search across files
Find all TODO comments in the codebase

Git Operations

# Stage and commit changes
/commit

# Commit, push, and open PR
/commit-push-pr

# Show diff
/diff

Task Management

# Create a background task
Please create a task to run the test suite in background

# List tasks
/tasks

# Stop a task
Please stop the test task

MCP Server Usage

# Add an MCP server
/mcp add filesystem npx -y @modelcontextprotocol/server-filesystem .

# Use MCP tools
Please use the filesystem server to list all TypeScript files

Architecture

High-Level Flow

User Input → REPL.tsx → QueryEngine → Claude API → Tool Execution → Response

Key Components

main.tsx - CLI entry point and argument parsing
entrypoints/init.ts - System initialization and configuration
screens/REPL.tsx - Interactive terminal UI
QueryEngine.ts - Message submission and query coordination
services/tools/ - Tool execution engine with concurrency control
services/mcp/ - MCP client and server management

Technology Stack

Component	Technology
Runtime	Bun
Language	TypeScript (TSX)
UI Framework	React 18+
Terminal UI	Ink (custom fork)
Schema Validation	Zod v4
CLI Parser	C

Name		Name	Last commit message	Last commit date
Latest commit History 3 Commits
assistant		assistant
bootstrap		bootstrap
bridge		bridge
buddy		buddy
cli		cli
commands		commands
components		components
constants		constants
context		context
coordinator		coordinator
entrypoints		entrypoints
hooks		hooks
ink		ink
keybindings		keybindings
memdir		memdir
migrations		migrations
moreright		moreright
native-ts		native-ts
outputStyles		outputStyles
plugins		plugins
query		query
remote		remote
schemas		schemas
screens		screens
server		server
services		services
skills		skills
state		state
tasks		tasks
tools		tools
types		types
upstreamproxy		upstreamproxy
utils		utils
vim		vim
voice		voice
.gitattributes		.gitattributes
QueryEngine.ts		QueryEngine.ts
README.md		README.md
Task.ts		Task.ts
Tool.ts		Tool.ts
commands.ts		commands.ts
context.ts		context.ts
cost-tracker.ts		cost-tracker.ts
costHook.ts		costHook.ts
dialogLaunchers.tsx		dialogLaunchers.tsx
history.ts		history.ts
ink.ts		ink.ts
interactiveHelpers.tsx		interactiveHelpers.tsx
main.tsx		main.tsx
projectOnboardingState.ts		projectOnboardingState.ts
query.ts		query.ts
replLauncher.tsx		replLauncher.tsx
setup.ts		setup.ts
tasks.ts		tasks.ts
tools.ts		tools.ts

Folders and files

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Claude Code CLI

Overview

Features

Core Capabilities

Advanced Features

Installation

Prerequisites

Install Options

Post-Installation Setup

Quick Start

Available Commands

Core Commands

Development Commands

Configuration Commands

Context & Memory

Session Management

Built-in Tools

File Operations

Execution

Web & Search

AI & Agents

MCP Integration

Configuration

Global Configuration (~/.claude.json)

Project Configuration (.claude.json)

MCP Configuration (.mcp.json)

Environment Variables

Usage Examples

Code Review

File Operations

Git Operations

Task Management

MCP Server Usage

Architecture

High-Level Flow

Key Components

Technology Stack

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