Claude Code

Anthropic’s terminal coding agent. It reads and edits files, runs commands and talks to MCP servers, under a permission system you control. Pairs with MCP and the Claude API.

Documentation: Claude Code docs · CLI reference · Settings · Hooks

Verification: CLI flags and subcommands were checked against claude --help (version 2.1.220). Slash commands, keyboard shortcuts, settings keys and file layouts are from the official docs and not executed here; those not confirmed are marked (unverified).

Start and Resume #

COMMAND	DESCRIPTION
`claude`	Start an interactive session in the current directory
`claude "PROMPT"`	Start interactive with an initial prompt
`claude -p "PROMPT"`	Print mode: answer and exit (headless)
`claude -c`	Continue the most recent conversation in this directory
`claude -r [ID_OR_SEARCH]`	Resume by session ID, or pick from a list
`claude -n NAME`	Name the session
`claude -w [NAME]`	Work in a new git worktree
`claude --from-pr [PR]`	Resume a session linked to a pull request
`claude --add-dir DIR`	Allow tool access to an extra directory
`claude update`	Check for and install updates
`claude doctor`	Check installation health
`claude auth login` / `claude auth status` / `claude auth logout`	Manage authentication
`claude setup-token`	Create a long-lived token for scripts and CI

Common Flags #

FLAG	DESCRIPTION
`--model MODEL`	Alias (`sonnet`, `opus`) or full model name
`--effort LEVEL`	`low`, `medium`, `high`, `xhigh` or `max`
`--permission-mode MODE`	`acceptEdits`, `auto`, `bypassPermissions`, `manual`, `dontAsk` or `plan`
`--allowedTools "Bash(git *)" Edit`	Tools allowed without prompting
`--disallowedTools TOOL`	Tools denied
`--tools TOOL...`	Restrict the set of available tools
`--append-system-prompt TEXT`	Add to the default system prompt
`--system-prompt TEXT`	Replace the system prompt
`--settings FILE_OR_JSON`	Load extra settings
`--setting-sources user,project,local`	Choose which settings sources load
`--mcp-config FILE...`	Load MCP servers from JSON
`--strict-mcp-config`	Use only servers from `--mcp-config`
`--agents JSON`	Define subagents inline
`--plugin-dir PATH`	Load a plugin from a directory
`--debug [FILTER]` / `--debug-file PATH`	Debug logging
`--safe-mode`	Start with all customisations disabled
`--dangerously-skip-permissions`	Skip every permission check. Only in a sandbox with no sensitive access

Headless Mode (`-p`) #

Options below only apply with -p.

COMMAND	DESCRIPTION
`claude -p "PROMPT" --output-format json`	One JSON result object
`claude -p "PROMPT" --output-format stream-json`	Streaming JSON events (add `--verbose` if the CLI asks for it)
`claude -p "PROMPT" --json-schema SCHEMA_JSON`	Validate output against a JSON Schema
`claude -p "PROMPT" --max-budget-usd 2`	Stop at a spend limit
`claude -p "PROMPT" --fallback-model sonnet`	Fall back if the model is overloaded
`claude -p "PROMPT" --no-session-persistence`	Do not save the session
`cat FILE \| claude -p "Summarise this"`	Pipe input

bash
git diff main... | claude -p "Review this diff for bugs" --output-format text

Slash Commands #

Type / in a session to list what is available (/help). Custom commands and skills appear in the same list.

COMMAND	DESCRIPTION
`/help`	Show help and commands
`/clear`	Start a fresh conversation
`/compact [FOCUS]`	Summarise history to free context
`/resume`	Pick a previous session
`/model`	Change model
`/config`	Open settings
`/permissions`	View or edit permission rules
`/memory`	Edit memory files (CLAUDE.md)
`/init`	Create a CLAUDE.md for the repo
`/mcp`	Manage MCP servers
`/agents`	Manage subagents
`/hooks`	View hook configuration
`/doctor`	Diagnose the install
`/cost`	Show token use and cost `(unverified)`
`/status`	Show version, model and account `(unverified)`
`/login` / `/logout`	Switch account
`/exit`	Quit

Keyboard Shortcuts #

Shortcuts are (unverified); use /help for the list on your version.

KEY	ACTION
`Esc`	Interrupt the current turn
`Esc Esc`	Rewind or edit an earlier message
`Shift+Tab`	Cycle permission modes
`Ctrl+C`	Cancel input or interrupt
`Ctrl+D`	Exit
`Ctrl+R`	Search prompt history
`@PATH`	Mention a file
`!COMMAND`	Run a shell command from the prompt

Settings and Permissions #

Settings merge from user (~/.claude/settings.json), project (.claude/settings.json, shared) and local (.claude/settings.local.json, not committed). Managed policy overrides all.

json
{
  "model": "sonnet",
  "permissions": {
    "allow": ["Bash(git status)", "Bash(git diff *)", "Read"],
    "ask": ["Bash(git push *)"],
    "deny": ["Read(./.env)", "Read(./secrets/**)"]
  },
  "env": { "EXAMPLE_VAR": "value" }
}

RULE FORM	MEANING
`Tool`	The whole tool (for example `Read`, `Edit`, `WebFetch`)
`Bash(PATTERN)`	Shell commands matching a pattern (`Bash(npm run test *)`)
`Read(PATH_GLOB)` / `Edit(PATH_GLOB)`	File access by path
`mcp__SERVER__TOOL`	A tool from an MCP server

Deny rules win over allow. Never rely on prompt text to protect secrets; deny the file read.

CLAUDE.md and Memory #

FILE	SCOPE
`~/.claude/CLAUDE.md`	Personal, all projects
`./CLAUDE.md`	Project, committed to git
`./CLAUDE.local.md`	Personal project notes, not committed `(unverified)`
`@path/to/file.md` inside CLAUDE.md	Import another file

Keep CLAUDE.md short and concrete: build and test commands, conventions, things not obvious from code. See Prompting and Context Engineering.

Hooks #

Hooks run your commands at lifecycle events. Configure in settings under hooks.

EVENT	FIRES
`PreToolUse`	Before a tool runs; can block it
`PostToolUse`	After a tool succeeds
`UserPromptSubmit`	When you submit a prompt
`Stop` / `SubagentStop`	When the agent or a subagent finishes
`SessionStart` / `SessionEnd`	Session boundaries
`Notification`	When Claude needs attention
`PreCompact`	Before context compaction

json
{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [{ "type": "command", "command": "/path/to/check-command.sh" }]
      }
    ]
  }
}

The hook receives event JSON on stdin. Exit code 2 blocks the action and feeds stderr back to Claude; 0 continues.

Skills and Subagents #

WHAT	WHERE
Skill	`.claude/skills/NAME/SKILL.md` (or `~/.claude/skills/NAME/`)
Subagent	`.claude/agents/NAME.md` (or `~/.claude/agents/`)
Plugin	`claude plugin install PLUGIN@MARKETPLACE`; also `enable`, `disable`, `details`

markdown
---
name: log-triage
description: Use when asked to find the cause of an error in logs.
---
Steps and instructions for the skill go here.

markdown
---
name: reviewer
description: Reviews diffs for bugs. Use after code changes.
tools: Read, Grep, Glob
model: sonnet
---
You review diffs and report problems with file and line.

MCP Servers #

COMMAND	DESCRIPTION
`claude mcp add --transport http NAME URL`	Add a remote HTTP server
`claude mcp add NAME -e KEY=VALUE -- COMMAND ARGS`	Add a local stdio server
`claude mcp add-json NAME 'JSON'`	Add from a JSON string
`claude mcp list`	List servers and health
`claude mcp get NAME`	Show one server
`claude mcp remove NAME`	Remove a server
`claude mcp login NAME` / `claude mcp logout NAME`	OAuth for a server
`claude mcp add -s user ...`	Scope: `local` (default), `user` or `project`
`claude mcp serve`	Run Claude Code itself as an MCP server

Project-scoped servers live in .mcp.json and need approval on first use. More in MCP.

Environment Variables #

VARIABLE	USE
`ANTHROPIC_API_KEY`	API key authentication instead of an account login
`ANTHROPIC_MODEL`	Default model `(unverified)`
`MAX_THINKING_TOKENS`	Extended thinking budget `(unverified)`
`CLAUDE_CODE_SIMPLE=1`	Same as `--bare` (set by that flag)