Claude Code

Installation

Install Claude Code:

curl -fsSL https://claude.ai/install.sh | bash

Starting a Session

Start an interactive session in the current directory:

claude

Pipe file contents to Claude:

cat $FILE | claude -p "$PROMPT"

Continue the most recent conversation:

claude -c

Resume a specific session by ID:

claude -r $SESSION_ID "$PROMPT"

CLI Flags

Flag	Description
`-p "$PROMPT"`	Non-interactive mode (print result and exit)
`-c`	Continue the most recent conversation
`-r $SESSION_ID`	Resume a session by ID
`--model $MODEL`	Specify Claude model (e.g. `claude-opus-4-5`, `claude-sonnet-4-5`)
`--add-dir $PATH`	Add an extra directory to the working context
`--output-format text/json/stream-json`	Choose the output format
`--max-turns $N`	Limit agent turns in non-interactive mode
`--allowedTools $TOOLS`	Comma-separated list of tools Claude may use
`--disallowedTools $TOOLS`	Comma-separated list of tools Claude may not use
`--append-system-prompt "$TEXT"`	Append custom instructions to the system prompt
`--allow-dangerously-skip-permissions`	Skip permission prompts (use with caution)

Update Claude Code to the latest version:

claude update

Slash Commands

Command	Description
`/bug`	Report a bug in the current session
`/clear`	Clear conversation history and start fresh
`/compact [instructions]`	Summarize context to save tokens while keeping key info
`/config`	Open settings (theme, output format, model, etc.)
`/cost`	Display API usage and estimated cost for the session
`/doctor`	Run diagnostics and environment validation
`/exit`	Exit the Claude Code session
`/help`	Show all available slash commands
`/init`	Create a `CLAUDE.md` project memory file in the repo root
`/mcp`	List connected MCP servers and their status
`/memory`	View or manage project and session memory
`/model`	Switch the Claude model for the current session
`/permissions`	Manage tool permissions
`/pr_comments`	Review pull request comments
`/release`	Trigger a release workflow
`/review`	Run a code review on recent changes
`/status`	Show session and configuration status
`/vim`	Toggle Vim keybindings

Keyboard Shortcuts

Shortcut	Description
`Ctrl+C`	Interrupt Claude's current response
`Ctrl+D`	Exit the session
`Esc`	Cancel/escape current output
`Esc` `Esc`	Open the rewind menu to undo recent changes
`Shift+Tab`	Toggle auto-accept mode
`Ctrl+G`	Open the prompt in an external editor
`Option+T` / `Alt+T`	Enable extended thinking mode
`Option+P` / `Alt+P`	Open the model picker

Project Memory (CLAUDE.md)

Initialize a CLAUDE.md file to give Claude persistent project context:

/init

This creates a CLAUDE.md in the repo root. Add project-specific conventions, architecture notes, and instructions that Claude will read at the start of every session:

# Project Context

## Architecture

- Backend: Node.js + Express
- Database: PostgreSQL
- Frontend: React

## Conventions

- Use kebab-case for file names
- All functions must have JSDoc comments
- Run `npm test` before committing

Custom Slash Commands

Create reusable project commands as markdown files:

Project-level (version-controlled): .claude/commands/$COMMAND_NAME.md
User-level (all projects): ~/.claude/commands/$COMMAND_NAME.md

Example .claude/commands/deploy-prod.md:

---
description: Deploy the application to production
---

Run the following steps to deploy:

1. Run `npm run build`
2. Run the test suite with `npm test`
3. Deploy using `./scripts/deploy.sh production`
   Report any errors and ask before proceeding to the next step.

This creates a /deploy-prod slash command inside Claude Code.

MCP (Model Context Protocol)

Add an MCP Server via CLI

Add a local stdio-based MCP server:

claude mcp add --transport stdio $SERVER_NAME -- $COMMAND $ARGS

Add a remote HTTP-based MCP server:

claude mcp add --transport http $SERVER_NAME $SERVER_URL

Add a server to a specific scope:

claude mcp add --scope user --transport stdio $SERVER_NAME -- $COMMAND $ARGS
claude mcp add --scope project --transport http $SERVER_NAME $SERVER_URL

Scope	Visibility	Config file
`local`	Current project, current user only	`.claude/settings.local.json`
`project`	Current project, all team members	`.claude/settings.json`
`user`	All projects for current user	`~/.claude.json`

Manage MCP Servers

List all configured MCP servers:

claude mcp list

Remove an MCP server:

claude mcp remove $SERVER_NAME

Configure MCP via Config File

Edit ~/.claude.json (user scope) or .claude/settings.json (project scope):

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/home/$USER/Documents"
      ],
      "env": {}
    },
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "$GITHUB_TOKEN"
      }
    },
    "postgres": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-postgres", "$DATABASE_URL"],
      "env": {}
    }
  }
}

Restart Claude Code after editing the config file for changes to take effect.