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Every CLI flag, slash command, keyboard shortcut, config key, hook event, and environment variable in one place. For deep explanations, see the full Claude Code guide. For first-time setup, see the quickstart.

1. Installation

Three installation methods, in order of preference.

# Native binary (recommended)
curl-fsSLhttps://claude.ai/install.sh|bash

# Homebrew (macOS)
brewinstall--caskclaude-code

# NPM (deprecated — migrate with `claude install`)
npminstall-g@anthropic-ai/claude-code

Install a specific version:

curl-fsSLhttps://claude.ai/install.sh|bash-s1.0.58

Verify installation:

claudedoctor
claude--version

Authenticate:

claudeauthlogin# Log in or switch accounts
claudeauthstatus# Check current auth state
claudeauthlogout# Clear stored credentials

2. CLI Flags

3. Slash Commands

Custom commands: Create .claude/commands/my-command.md (project) or ~/.claude/commands/my-command.md (personal) and invoke with /my-command. Commands support YAML frontmatter for description, allowed tools, model override, and argument interpolation via $ARGUMENTS or positional $1, $2.

---
description: Fix a GitHub issue
allowed-tools: Read, Edit, Bash(git:*)
model: opus
argument-hint: [issue-number]
---

Fix GitHub issue #$ARGUMENTS following our coding standards.

Usage: /fix-issue 123

4. Keyboard Shortcuts

General Controls

Quick Prefixes

Multiline Input

Keybindings are customizable via /keybindings (stored in ~/.claude/keybindings.json).

5. Configuration Files

Precedence Hierarchy (highest to lowest)

First match wins. Enterprise settings cannot be bypassed.

6. Settings.json Reference

Key settings with types and examples. Place in any settings file from the hierarchy above.

{
"$schema":"https://json.schemastore.org/claude-code-settings.json",
"model":"claude-sonnet-4-6",
"permissions":{
"allow":["Read","Glob","Grep","Bash(npm run:*)","Bash(git:*)","Edit(src/**)"],
"deny":["Read(.env*)","Bash(rm -rf:*)","Bash(sudo:*)"],
"ask":["WebFetch","Bash(docker:*)"],
"defaultMode":"acceptEdits",
"additionalDirectories":["../shared-lib"]
},
"env":{
"NODE_ENV":"development"
},
"hooks":{},
"sandbox":{
"enabled":false,
"autoAllowBashIfSandboxed":true
},
"includeCoAuthoredBy":true,
"cleanupPeriodDays":30,
"respectGitignore":true,
"showTurnDuration":true,
"language":"en",
"autoMemoryDirectory":".claude/memory",
"plansDirectory":".claude/plans"
}

Permission rule syntax: Tool(pattern:*) provides prefix matching. Bash(npm run test:*) allows npm run test, npm run test:unit, etc. File patterns use glob syntax: Edit(src/**).

New keys (v2.1.118+):

For the complete settings schema, see the Configuration Deep Dive in the full guide.

7. CLAUDE.md Quick Reference

CLAUDE.md is your project’s instruction file. Claude reads it at the start of every session.

Where it lives:

What to include:

# Project Name

## Stack
-Backend: FastAPI, Python 3.11+
-Frontend: HTMX + Alpine.js + Bootstrap 5

## Commands
-Dev: `uvicorn app.main:app --reload --port 8000`
-Test: `python -m pytest -v`
-Lint: `ruff check .`

## Conventions
-Conventional commits: feat:, fix:, docs:, refactor:
-Never force push to main
-Always activate venv before Python commands

## Key Files
-app/main.py — FastAPI app and routes
-app/models.py — SQLAlchemy models

Keep it scannable. Dense prose wastes context tokens every session. Use bullet points, tables, and short code blocks. Avoid long paragraphs — Claude reads CLAUDE.md at the start of every session, so every word costs context.

Pro tips: - Use # prefix in the REPL to add things to auto-memory without editing CLAUDE.md: # Always use TypeScript strict mode - CLAUDE.md in subdirectories is loaded when Claude reads files in that directory - Team-shared rules go in .claude/rules/*.md for modular organization

8. Permission Modes

Auto Mode (v2.1.85+) is the recommended replacement for --dangerously-skip-permissions. Read-only and file edits are auto-approved. Custom allow/deny rules resolve first. Everything else goes to the safety classifier. Auto-blocked by default: curl | bash, force-push to main, production deploys, mass cloud deletions, IAM changes, sending sensitive data externally.¹

Circuit breaker: 3 consecutive blocks or 20 total in a session pauses back to manual prompting.

# Enable at startup
claude--enable-auto-mode

# Cycle during session
Shift+Tab# default -> acceptEdits -> auto -> plan

PowerShell auto-approval (v2.1.119+): PowerShell tool commands auto-approve in permission mode the same way Bash commands do. Allow rules like PowerShell(Get-*:*) bypass prompts for read-only operations. Use v2.1.149+ on PowerShell-heavy workflows; it fixes built-in cd permission bypasses, prefix/wildcard allow-rule matching, and stale directory variable tracking.

9. Hook Events

| InstructionsLoaded | CLAUDE.md loaded | No | | ConfigChange | Config file changes mid-session | Yes | | WorktreeCreate | Worktree being created | Yes | | WorktreeRemove | Worktree being removed | No | | PreCompact | Before context compaction | No | | PostCompact | After context compaction | No | | Elicitation | MCP requests structured input | Yes | | ElicitationResult | User responds to MCP dialog | Yes | | StopFailure | Turn ends due to API error | No | | PermissionRequest | Permission dialog shown | Yes | | PermissionDenied | Auto mode denies an action (v2.1.88+) | No | | CwdChanged | Working directory changes (v2.1.83+) | No | | FileChanged | Watched file modified externally (v2.1.83+) | No | | TaskCreated | New task created (v2.1.84+) | No | | TeammateIdle | Agent team member idles | Yes | | TaskCompleted | Task marked complete | Yes |

For the full hook protocol (input/output JSON, matchers, exit codes), see Hooks Deep Dive in the full guide.

10. Hook Configuration

Hooks live in settings.json or a dedicated hooks.json. Minimal example:

{
"hooks":{
"PostToolUse":[
{
"matcher":"Edit|Write",
"hooks":[
{
"type":"command",
"command":"npx prettier --write \"$FILE_PATH\""
}
]
}
],
"PreToolUse":[
{
"matcher":"Bash",
"hooks":[
{
"type":"command",
"command":".claude/hooks/validate-bash.sh"
}
]
}
]
}
}

Matcher syntax:

Exit codes:

Async hooks run in the background without blocking: add "async": true to the hook object.²

Hook output / input fields:

• duration_ms on PostToolUse / PostToolUseFailure hook input (v2.1.119+) — tool execution time excluding permission prompts and PreToolUse hooks.
• hookSpecificOutput.updatedToolOutput (v2.1.121+) — replace tool output for any tool (v2.1.118 introduced this for MCP only; v2.1.121 extends to all tools).
• hookSpecificOutput.sessionTitle (v2.1.96+) — set session title from a UserPromptSubmit hook.
• args: string[] on command hooks (v2.1.139+) — pass structured argv without shell quoting.
• continueOnBlock on PostToolUse hooks (v2.1.139+) — feed the block reason back to Claude and continue the turn.
• subagent_type on agent hook input (v2.1.140+) — identify which agent type is running.
• terminalSequence in hook JSON output (v2.1.141+) — emit terminal-control sequences for notifications, window titles, and bells.

11. MCP Quick Setup

Add an MCP server in one command:

# Remote HTTP server (recommended)
claudemcpadd--transporthttpgithubhttps://api.githubcopilot.com/mcp/

# Remote with auth header
claudemcpadd--transporthttpapihttps://api.example.com/mcp\
--header"Authorization: Bearer $TOKEN"

# Local stdio server
claudemcpadd--transportstdiopostgres\
--env"DATABASE_URL=postgresql://user:pass@localhost/db"\
--npx-y@anthropic-ai/mcp-server-postgres

Scope control:

claudemcpadd--scopeproject...# Team-shared (.mcp.json)
claudemcpadd--scopeuser...# Personal (~/.claude.json)

Project .mcp.json example:

{
"mcpServers":{
"github":{
"type":"http",
"url":"https://api.githubcopilot.com/mcp/"
},
"database":{
"type":"stdio",
"command":"npx",
"args":["-y","@anthropic-ai/mcp-server-postgres"],
"env":{
"DATABASE_URL":"postgresql://user:pass@localhost/db"
}
}
}
}

MCP now has 100 million monthly downloads and 3,000+ indexed servers.³ For transport types, elicitation, and tool search configuration, see the MCP section in the full guide.

alwaysLoad (v2.1.121+): Opt a trusted server out of Tool Search deferral. All its tools load at session start, no ToolSearch round-trip:

{
"mcpServers":{
"github":{
"type":"http",
"url":"https://api.githubcopilot.com/mcp/",
"alwaysLoad":true
}
}
}

Auto-retry (v2.1.121+): MCP servers that error during startup are retried up to 3 times before being marked disconnected.

SDK mcp_authenticate redirectUri (v2.1.121+): Required for completing OAuth on custom URI schemes — desktop apps and claude.ai connector flows.

11.5. Plugin CLI Commands

12. Subagent Types

Claude automatically delegates to subagents. You can also request them explicitly:

> Use the explore agent to find all auth-related files
> Have a subagent analyze the database schema

Custom subagents are defined in .claude/agents/ (project) or ~/.claude/agents/ (personal) as markdown files with YAML frontmatter. Up to 10 subagents can run in parallel.⁴

claude agents opens Agent View in current releases: a research-preview operations screen for running, blocked, and completed Claude Code sessions. claude agents --cwd <path> scopes the view to one directory (v2.1.141+), v2.1.142 adds dispatch flags for background sessions, and v2.1.143 applies those flags consistently to the dashboard and background sessions: --add-dir, --settings, --mcp-config, --plugin-dir, --permission-mode, --model, --effort, and --dangerously-skip-permissions. v2.1.144 adds /resume support for background sessions and marks them with bg; v2.1.145 adds claude agents --json, awaiting-input tab counts, and Agent View reply-pane fixes; v2.1.147 adds pinned background sessions that stay alive when idle and restart in place for updates. Use Agent View for monitoring, not as proof that the work passed quality gates.⁶

Custom agent frontmatter fields:

Example custom agent (.claude/agents/security-reviewer.md):

---
name: security-reviewer
description: Expert security code reviewer. Use PROACTIVELY after code changes to auth or data handling.
tools: Read, Grep, Glob, Bash
model: opus
permissionMode: plan
---

You are a senior security engineer. Analyze for OWASP Top 10 vulnerabilities,
secrets, hardcoded credentials, and SQL injection. Report findings with severity
levels and remediation steps.

13. Environment Variables

Authentication and API

Model Configuration

Cloud Providers

Behavior Control

Tool Configuration

Network and Proxy

For the complete list, see Environment Variables in the full guide.

14. Cost Reference

Pricing per 1 million tokens (as of April 2026).⁵

A typical session consumes 50K-200K input tokens and 10K-50K output tokens. Haiku session: $0.10-$0.45. Opus session: $0.50-$2.25.

Default model by plan (Claude Code as of April 16, 2026):

• Max, Team Premium → Opus 4.7
• Pro, Team Standard, Enterprise, Anthropic API → Sonnet 4.6 (Enterprise + API switch to Opus 4.7 on April 23, 2026)
• Bedrock, Vertex, Foundry → Sonnet 4.5 (pin newer via ANTHROPIC_DEFAULT_OPUS_MODEL)

Opus 4.7 requires Claude Code v2.1.111 or later. It uses adaptive reasoning only (no fixed thinking budgets). New xhigh effort level is the default for coding/agentic workloads on Opus 4.7.

Switch models during a session:

/modelopus#SwitchtoOpus(resolvesto4.7onAPI,4.6onBedrock/Vertex/Foundry)
/modelsonnet#SwitchtoSonnet4.6
/modelhaiku#SwitchtoHaiku4.5
/effortxhigh#Opus4.7only—recommendedforcoding/agentic

Decision rule: Simple exploration goes to Haiku. Cost-sensitive daily coding goes to Sonnet. Hard reasoning, architecture, agentic loops, and security analysis go to Opus. Use opusplan for complex refactoring (Opus plans, Sonnet executes).

15. Key File Locations

16. Changelog

17. References

This cheat sheet is the quick-lookup companion to the full Claude Code CLI guide. For setup walkthroughs, see the Claude Code quickstart. For iOS and macOS projects specifically, see the iOS Agent Development guide, the XcodeBuildMCP integration patterns, and the Apple Ecosystem Series. Last updated May 24, 2026.