CLI Reference Complete reference for Claude Code command line interface. When to Use "What CLI flags are available?" "How do I use headless mode?" "Claude in automation/CI/CD" "Output format options" "System prompt via CLI" "How do I spawn agents properly?" Core Commands Command Description Example claude Start interactive REPL claude claude "query" REPL with initial prompt claude "explain this project" claude p "query" Headless mode (SDK) claude p "explain function" cat file \ claude p Process piped content cat logs.txt \ claude p "explain" claude c Continue most recent claude c claude c p "query" Continue via SDK claude c p "check types" claude r "id" "query" Resume session claude r "auth" "finish PR" claude update Update version claude update claude mcp Configure MCP servers See MCP docs Session Control Flag Description Example continue, c Load most recent conversation claude continue resume, r Resume session by ID/name claude resume auth refactor session id Use specific UUID claude session id "550e8400 ..." fork session Create new session on resume claude resume abc fork session Headless Mode (Critical for Agents) Flag Description Example print, p Non interactive, exit after claude p "query" output format text , json , stream json claude p output format json max turns Limit agentic turns claude p max turns 100 "query" verbose Full turn by turn output claude verbose dangerously skip permissions Skip permission prompts claude p dangerously skip permissions include partial messages Include streaming events claude p output format stream json include partial messages input format Input format (text/stream json) claude p input format stream json Tool Control Flag Description Example allowedTools Auto approve these tools "Bash(git log: )" "Read" disallowedTools Block these tools "Bash(rm: )" "Edit" tools Only allow these tools tools "Bash,Edit,Read" Subagent Definition ( agents flag) Define custom subagents inline via JSON: Agent Fields Field Required Description description Yes When to invoke this agent prompt Yes System prompt for behavior tools No Allowed tools (inherits all if omitted) model No sonnet , haiku , or claude opus 4 5 20251101 Key Insight When Lead uses Task tool, it auto spawns from these definitions. No manual spawn needed. System Prompt Customization Flag Behavior Modes system prompt Replace entire prompt Interactive + Print system prompt file Replace from file Print only append system prompt Append to default (recommended) Interactive + Print Use append system prompt for most cases preserves Claude Code capabilities. Model Selection Flag Description Example model Set model for session model claude sonnet 4 5 fallback model Fallback if default overloaded fallback model sonnet Aliases: sonnet , opus , haiku MCP Configuration Flag Description Example mcp config Load MCP servers from JSON mcp config ./mcp.json strict mcp config Only use these MCP servers strict mcp config mcp config ./mcp.json Advanced Flags Flag Description Example add dir Add working directories add dir ../apps ../lib agent Specify agent for session agent my custom agent permission mode Start in permission mode permission mode plan permission prompt tool MCP tool for permissions permission prompt tool mcp auth plugin dir Load plugins from directory plugin dir ./my plugins settings Load settings from file/JSON settings ./settings.json setting sources Which settings to load setting sources user,project betas Beta API headers betas interleaved thinking debug Enable debug mode debug "api,hooks" ide Auto connect to IDE ide chrome Enable Chrome integration chrome no chrome Disable Chrome for session no chrome enable lsp logging Verbose LSP debugging enable lsp logging version, v Output version claude v Output Formats JSON (for parsing) Streaming (for real time monitoring) Structured Output (schema validation) Headless Agent Pattern (CRITICAL) Proper headless agent spawn: Missing any of these causes hangs: session id Track the session dangerously skip permissions Headless requires this max turns Prevents infinite loops Common Patterns CI/CD Automation Piped Input Multi turn Session Stream Monitoring Keyboard Shortcuts (Interactive) Shortcut Action Ctrl+C Cancel current Ctrl+D Exit Ctrl+R Reverse search history Esc Esc Rewind changes Shift+Tab Toggle permission mode Quick Commands Prefix Action / Slash command ! Bash mode Add to memory @ File mention

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