CLI Reference

Overview

The Claude Code CLI (Command Line Interface) is the primary way to interact with Claude Code. It provides powerful options for running queries, managing sessions, configuring models, and integrating Claude into your development workflows.

Architecture

Runtime & Packaging

Since v2.1.113, the Claude Code CLI launches a native per-platform binary (macOS, Linux, Windows) via optional npm dependencies. The binary is matched to your OS and architecture at install time — the older bundled-JavaScript runtime is no longer the default on macOS or Linux.

The user-facing install is unchanged: npm install -g @anthropic-ai/claude-code still works and remains the recommended path. Behind the scenes npm fetches the correct native binary for your platform.

Download host (v2.1.116+): native-binary artifacts are served from https://downloads.claude.ai/claude-code-releases.

Corporate / proxy users: If your network requires an explicit allowlist, add downloads.claude.ai (and https://downloads.claude.ai/claude-code-releases) to your proxy egress rules. Environments that previously allowlisted only storage.googleapis.com or the npm registry will need to be updated or claude update and the initial install will fail.

The older JavaScript bundle is still produced for Windows and for environments that pin to it; those installs continue to ship Glob and Grep as first-class tools (see the Glob/Grep footnote under Tools).

CLI Commands

Command	Description	Example
`claude`	Start interactive REPL	`claude`
`claude "query"`	Start REPL with initial prompt	`claude "explain this project"`
`claude -p "query"`	Print mode - query then exit	`claude -p "explain this function"`
`cat file \| claude -p "query"`	Process piped content	`cat logs.txt \| claude -p "explain"`
`claude -c`	Continue most recent conversation	`claude -c`
`claude -c -p "query"`	Continue in print mode	`claude -c -p "check for type errors"`
`claude -r "<session>" "query"`	Resume session by ID or name	`claude -r "auth-refactor" "finish this PR"`
`claude update`	Update to latest version	`claude update`
`/doctor` (slash command)	Diagnose installation, config, and plugin health. Since v2.1.116 it can be opened while Claude is responding, shows status icons inline, and accepts the `f` keypress to auto-fix detected issues	run `/doctor` inside the REPL
`claude mcp`	Configure MCP servers	See MCP documentation
`claude mcp serve`	Run Claude Code as an MCP server	`claude mcp serve`
`claude agents`	List all configured subagents	`claude agents`
`claude auto-mode defaults`	Print auto mode default rules as JSON	`claude auto-mode defaults`
`claude remote-control`	Start Remote Control server	`claude remote-control`
`claude plugin`	Manage plugins (install, enable, disable)	`claude plugin install my-plugin`
`claude plugin tag <version>`	Create a release git tag for a plugin with version validation (v2.1.118+)	`claude plugin tag v0.3.0`
`claude install [version]`	Install a specific native-binary version. Accepts `stable`, `latest`, or an explicit version string	`claude install 2.1.126`
`claude project purge [path]`	Delete all local Claude Code state for a project (transcripts, tasks, debug logs, file-edit history, prompt history, and `~/.claude.json` entry). Omit `[path]` for an interactive picker. Flags: `--dry-run` to preview, `-y/--yes` to skip confirmation, `-i/--interactive` to confirm each item, `--all` for every project (v2.1.126+)	`claude project purge ~/work/repo --dry-run`
`claude plugin prune`	Remove orphaned auto-installed plugin dependencies (parent plugin gone). `plugin uninstall --prune` does the same cascade after uninstalling a target (v2.1.121+)	`claude plugin prune`
`claude ultrareview [target]`	Run `/ultrareview` non-interactively. Prints findings to stdout, exits 0 on success / 1 on failure. Use `--json` for raw payload, `--timeout <minutes>` to override the 30-minute default (v2.1.120+)	`claude ultrareview 1234 --json`
`claude auth login`	Log in (supports `--email`, `--sso`). Since v2.1.126, accepts the OAuth code pasted into the terminal as a fallback when the browser callback can't reach localhost (WSL2, SSH, containers)	`claude auth login --email user@example.com`
`claude auth logout`	Log out of current account	`claude auth logout`
`claude auth status`	Check auth status (exit 0 if logged in, 1 if not)	`claude auth status`

Core Flags

Flag	Description	Example
`-p, --print`	Print response without interactive mode	`claude -p "query"`
`-c, --continue`	Load most recent conversation	`claude --continue`
`-r, --resume`	Resume specific session by ID or name	`claude --resume auth-refactor`
`-v, --version`	Output version number	`claude -v`
`-w, --worktree`	Start in isolated git worktree	`claude -w`
`-n, --name`	Session display name	`claude -n "auth-refactor"`
`--from-pr <url-or-number>`	Resume sessions linked to a pull/merge request. Accepts GitHub (cloud + Enterprise), GitLab MR, and Bitbucket PR URLs since v2.1.119; previously GitHub.com only	`claude --from-pr 42` or `claude --from-pr https://gitlab.example.com/org/repo/-/merge_requests/17`
`--remote "task"`	Create web session on claude.ai	`claude --remote "implement API"`
`--remote-control, --rc`	Interactive session with Remote Control	`claude --rc`
`--teleport`	Resume web session locally	`claude --teleport`
`--teammate-mode`	Agent team display mode	`claude --teammate-mode tmux`
`--bare`	Minimal mode (skip hooks, skills, plugins, MCP, auto memory, CLAUDE.md)	`claude --bare`
`--enable-auto-mode`	Unlock auto permission mode (no longer required for Max subscribers on Opus 4.7)	`claude --enable-auto-mode`
`--channels`	Subscribe to MCP channel plugins	`claude --channels discord,telegram`
`--chrome` / `--no-chrome`	Enable/disable Chrome browser integration	`claude --chrome`
`--effort`	Set thinking effort level	`claude --effort high`
`--init` / `--init-only`	Run initialization hooks	`claude --init`
`--maintenance`	Run maintenance hooks and exit	`claude --maintenance`
`--disable-slash-commands`	Disable all skills and slash commands	`claude --disable-slash-commands`
`--no-session-persistence`	Disable session saving (print mode)	`claude -p --no-session-persistence "query"`
`--exclude-dynamic-system-prompt-sections`	Exclude dynamic sections from the system prompt for better prompt cache hit rates	`claude -p --exclude-dynamic-system-prompt-sections "query"`

Interactive vs Print Mode

Interactive Mode (default):

bash

# Start interactive session
claude

# Start with initial prompt
claude "explain the authentication flow"

Print Mode (non-interactive):

bash

# Single query, then exit
claude -p "what does this function do?"

# Process file content
cat error.log | claude -p "explain this error"

# Chain with other tools
claude -p "list todos" | grep "URGENT"

Model & Configuration

Flag	Description	Example
`--model`	Set model (sonnet, opus, haiku, or full name)	`claude --model opus`
`--fallback-model`	Automatic model fallback when overloaded	`claude -p --fallback-model sonnet "query"`
`--agent`	Specify agent for session	`claude --agent my-custom-agent`
`--agents`	Define custom subagents via JSON	See Agents Configuration
`--effort`	Set effort level (low, medium, high, xhigh, max)	`claude --effort xhigh`

Model Selection Examples

bash

# Use Opus 4.7 for complex tasks
claude --model opus "design a caching strategy"

# Use Haiku 4.5 for quick tasks
claude --model haiku -p "format this JSON"

# Full model name
claude --model claude-sonnet-4-6-20250929 "review this code"

# With fallback for reliability
claude -p --model opus --fallback-model sonnet "analyze architecture"

# Use opusplan (Opus plans, Sonnet executes)
claude --model opusplan "design and implement the caching layer"

Gateway model discovery (v2.1.126+): When ANTHROPIC_BASE_URL points at an Anthropic-compatible gateway, /model populates its picker from the gateway's /v1/models endpoint instead of the hard-coded list — useful for self-hosted proxies that expose a different model lineup.

System Prompt Customization

Flag	Description	Example
`--system-prompt`	Replace entire default prompt	`claude --system-prompt "You are a Python expert"`
`--system-prompt-file`	Load prompt from file (print mode)	`claude -p --system-prompt-file ./prompt.txt "query"`
`--append-system-prompt`	Append to default prompt	`claude --append-system-prompt "Always use TypeScript"`

System Prompt Examples

bash

# Complete custom persona
claude --system-prompt "You are a senior security engineer. Focus on vulnerabilities."

# Append specific instructions
claude --append-system-prompt "Always include unit tests with code examples"

# Load complex prompt from file
claude -p --system-prompt-file ./prompts/code-reviewer.txt "review main.py"

System Prompt Flags Comparison

Flag	Behavior	Interactive	Print
`--system-prompt`	Replaces entire default system prompt	✅	✅
`--system-prompt-file`	Replaces with prompt from file	❌	✅
`--append-system-prompt`	Appends to default system prompt	✅	✅

Use --system-prompt-file only in print mode. For interactive mode, use --system-prompt or --append-system-prompt.

Tool & Permission Management

Flag	Description	Example
`--tools`	Restrict available built-in tools	`claude -p --tools "Bash,Edit,Read" "query"`
`--allowedTools`	Tools that execute without prompting	`"Bash(git log:*)" "Read"`
`--disallowedTools`	Tools removed from context	`"Bash(rm:*)" "Edit"`
`--dangerously-skip-permissions`	Skip all permission prompts	`claude --dangerously-skip-permissions`
`--permission-mode`	Begin in specified permission mode	`claude --permission-mode auto`
`--permission-prompt-tool`	MCP tool for permission handling	`claude -p --permission-prompt-tool mcp_auth "query"`
`--enable-auto-mode`	Unlock auto permission mode	`claude --enable-auto-mode`

Glob / Grep footnote (v2.1.113+): On native macOS/Linux builds, Glob and Grep are provided as the embedded bfs and ugrep binaries invoked through the Bash tool rather than as separate first-class tools. Windows and npm-bundled (JS) installs still expose them as standalone tools. For subagent allowedTools / disallowedTools lists the backend substitution is transparent — you can keep referring to Glob / Grep in your configuration on every platform.

PowerShell auto-approve (v2.1.119): PowerShell tool commands can be auto-approved in permission mode exactly the same way Bash commands are. Use the same matcher syntax you already use for Bash(...) rules to scope PowerShell permissions — for example, PowerShell(Get-ChildItem:*).

Permission Examples

bash

# Read-only mode for code review
claude --permission-mode plan "review this codebase"

# Restrict to safe tools only
claude --tools "Read,Grep,Glob" -p "find all TODO comments"

# Allow specific git commands without prompts
claude --allowedTools "Bash(git status:*)" "Bash(git log:*)"

# Block dangerous operations
claude --disallowedTools "Bash(rm -rf:*)" "Bash(git push --force:*)"

Output & Format

Flag	Description	Options	Example
`--output-format`	Specify output format (print mode)	`text`, `json`, `stream-json`	`claude -p --output-format json "query"`
`--input-format`	Specify input format (print mode)	`text`, `stream-json`	`claude -p --input-format stream-json`
`--verbose`	Enable verbose logging		`claude --verbose`
`--include-partial-messages`	Include streaming events	Requires `stream-json`	`claude -p --output-format stream-json --include-partial-messages "query"`
`--json-schema`	Get validated JSON matching schema		`claude -p --json-schema '{"type":"object"}' "query"`
`--max-budget-usd`	Maximum spend for print mode		`claude -p --max-budget-usd 5.00 "query"`

Output Format Examples

bash

# Plain text (default)
claude -p "explain this code"

# JSON for programmatic use
claude -p --output-format json "list all functions in main.py"

# Streaming JSON for real-time processing
claude -p --output-format stream-json "generate a long report"

# Structured output with schema validation
claude -p --json-schema '{"type":"object","properties":{"bugs":{"type":"array"}}}' \
  "find bugs in this code and return as JSON"

Workspace & Directory

Flag	Description	Example
`--add-dir`	Add additional working directories	`claude --add-dir ../apps ../lib`
`--setting-sources`	Comma-separated setting sources	`claude --setting-sources user,project`

/config persistence (v2.1.119): Changes made interactively via the /config command are now written to ~/.claude/settings.json and participate in the normal precedence chain (project → local → policy → user). Before v2.1.119, some /config changes were session-only. See Memory & Settings for the full precedence order. | --settings | Load settings from file or JSON | claude --settings ./settings.json | | --plugin-dir | Load plugins from directory (repeatable) | claude --plugin-dir ./my-plugin |

Multi-Directory Example

bash

# Work across multiple project directories
claude --add-dir ../frontend ../backend ../shared "find all API endpoints"

# Load custom settings
claude --settings '{"model":"opus","verbose":true}' "complex task"

MCP Configuration

Flag	Description	Example
`--mcp-config`	Load MCP servers from JSON	`claude --mcp-config ./mcp.json`
`--strict-mcp-config`	Only use specified MCP config	`claude --strict-mcp-config --mcp-config ./mcp.json`
`--channels`	Subscribe to MCP channel plugins	`claude --channels discord,telegram`

MCP Examples

bash

# Load GitHub MCP server
claude --mcp-config ./github-mcp.json "list open PRs"

# Strict mode - only specified servers
claude --strict-mcp-config --mcp-config ./production-mcp.json "deploy to staging"

Session Management

Flag	Description	Example
`--session-id`	Use specific session ID (UUID)	`claude --session-id "550e8400-..."`
`--fork-session`	Create new session when resuming	`claude --resume abc123 --fork-session`

Session Examples

bash

# Continue last conversation
claude -c

# Resume named session
claude -r "feature-auth" "continue implementing login"

# Fork session for experimentation
claude --resume feature-auth --fork-session "try alternative approach"

# Use specific session ID
claude --session-id "550e8400-e29b-41d4-a716-446655440000" "continue"

Session Fork

Create a branch from an existing session for experimentation:

bash

# Fork a session to try a different approach
claude --resume abc123 --fork-session "try alternative implementation"

# Fork with a custom message
claude -r "feature-auth" --fork-session "test with different architecture"

Use Cases:

Try alternative implementations without losing the original session
Experiment with different approaches in parallel
Create branches from successful work for variations
Test breaking changes without affecting the main session

The original session remains unchanged, and the fork becomes a new independent session.

Project State Cleanup (v2.1.126+)

claude project purge deletes all local Claude Code state for a project — transcripts, task lists, debug logs, file-edit history, prompt history lines, and the project's ~/.claude.json entry. Use --dry-run first to preview the deletion; --all walks every project on the machine.

bash

# Preview what would be deleted (safe)
claude project purge ~/work/repo --dry-run

# Delete state for a specific project, no prompts
claude project purge ~/work/repo --yes

# Walk every project interactively
claude project purge --all --interactive

Advanced Features

Flag	Description	Example
`--chrome`	Enable Chrome browser integration	`claude --chrome`
`--no-chrome`	Disable Chrome browser integration	`claude --no-chrome`
`--ide`	Auto-connect to IDE if available	`claude --ide`
`--max-turns`	Limit agentic turns (non-interactive)	`claude -p --max-turns 3 "query"`
`--debug`	Enable debug mode with filtering	`claude --debug "api,mcp"`
`--enable-lsp-logging`	Enable verbose LSP logging	`claude --enable-lsp-logging`
`--betas`	Beta headers for API requests	`claude --betas interleaved-thinking`
`--plugin-dir`	Load plugins from directory (repeatable)	`claude --plugin-dir ./my-plugin`
`--enable-auto-mode`	Unlock auto permission mode	`claude --enable-auto-mode`
`--effort`	Set thinking effort level	`claude --effort high`
`--bare`	Minimal mode (skip hooks, skills, plugins, MCP, auto memory, CLAUDE.md)	`claude --bare`
`--channels`	Subscribe to MCP channel plugins	`claude --channels discord`
`--tmux`	Create tmux session for worktree	`claude --tmux`
`--fork-session`	Create new session ID when resuming	`claude --resume abc --fork-session`
`--max-budget-usd`	Maximum spend (print mode)	`claude -p --max-budget-usd 5.00 "query"`
`--json-schema`	Validated JSON output	`claude -p --json-schema '{"type":"object"}' "q"`

Platform & Theme Notes (v2.1.112)

PowerShell tool on Windows: A dedicated PowerShell tool is rolling out on Windows and is controllable via environment variable.
Auto (match terminal) theme: The new "Auto (match terminal)" theme syncs Claude Code's light/dark appearance with your terminal.
Quieter permission prompts: Read-only Bash invocations and Glob patterns no longer trigger permission prompts.

Advanced Examples

bash

# Limit autonomous actions
claude -p --max-turns 5 "refactor this module"

# Debug API calls
claude --debug "api" "test query"

# Enable IDE integration
claude --ide "help me with this file"

Agents Configuration

The --agents flag accepts a JSON object defining custom subagents for a session.

Agents JSON Format

json

{
  "agent-name": {
    "description": "Required: when to invoke this agent",
    "prompt": "Required: system prompt for the agent",
    "tools": ["Optional", "array", "of", "tools"],
    "model": "optional: sonnet|opus|haiku"
  }
}

Required Fields:

description - Natural language description of when to use this agent
prompt - System prompt that defines the agent's role and behavior

Optional Fields:

tools - Array of available tools (inherits all if omitted)
- Format: ["Read", "Grep", "Glob", "Bash"]
model - Model to use: sonnet, opus, or haiku

Complete Agents Example

json

{
  "code-reviewer": {
    "description": "Expert code reviewer. Use proactively after code changes.",
    "prompt": "You are a senior code reviewer. Focus on code quality, security, and best practices.",
    "tools": ["Read", "Grep", "Glob", "Bash"],
    "model": "sonnet"
  },
  "debugger": {
    "description": "Debugging specialist for errors and test failures.",
    "prompt": "You are an expert debugger. Analyze errors, identify root causes, and provide fixes.",
    "tools": ["Read", "Edit", "Bash", "Grep"],
    "model": "opus"
  },
  "documenter": {
    "description": "Documentation specialist for generating guides.",
    "prompt": "You are a technical writer. Create clear, comprehensive documentation.",
    "tools": ["Read", "Write"],
    "model": "haiku"
  }
}

Agents Command Examples

bash

# Define custom agents inline
claude --agents '{
  "security-auditor": {
    "description": "Security specialist for vulnerability analysis",
    "prompt": "You are a security expert. Find vulnerabilities and suggest fixes.",
    "tools": ["Read", "Grep", "Glob"],
    "model": "opus"
  }
}' "audit this codebase for security issues"

# Load agents from file
claude --agents "$(cat ~/.claude/agents.json)" "review the auth module"

# Combine with other flags
claude -p --agents "$(cat agents.json)" --model sonnet "analyze performance"

Agent Priority

When multiple agent definitions exist, they are loaded in this priority order:

CLI-defined (--agents flag) - Session-specific
Project-level (.claude/agents/) - Current project
User-level (~/.claude/agents/) - All projects

CLI-defined agents override both project and user agents for the session. Project-level agents override user-level agents when their names collide. See Lesson 04 — Subagents for the full priority table including plugin-level agents.

High-Value Use Cases

1. CI/CD Integration

Use Claude Code in your CI/CD pipelines for automated code review, testing, and documentation.

GitHub Actions Example:

yaml

name: AI Code Review

on: [pull_request]

jobs:
  review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Install Claude Code
        run: npm install -g @anthropic-ai/claude-code

      - name: Run Code Review
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
        run: |
          claude -p --output-format json \
            --max-turns 1 \
            "Review the changes in this PR for:
            - Security vulnerabilities
            - Performance issues
            - Code quality
            Output as JSON with 'issues' array" > review.json

      - name: Post Review Comment
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const review = JSON.parse(fs.readFileSync('review.json', 'utf8'));
            // Process and post review comments

Jenkins Pipeline:

groovy

pipeline {
    agent any
    stages {
        stage('AI Review') {
            steps {
                sh '''
                    claude -p --output-format json \
                      --max-turns 3 \
                      "Analyze test coverage and suggest missing tests" \
                      > coverage-analysis.json
                '''
            }
        }
    }
}

Headless ultrareview (v2.1.120+):

yaml

# .github/workflows/ultrareview.yml
- name: Claude ultrareview
  run: claude ultrareview ${{ github.event.pull_request.number }} --json > review.json

claude ultrareview exits 0 on a clean review and 1 when findings are reported, so it's a drop-in PR gate. Use --timeout <minutes> to override the 30-minute default.

2. Script Piping

Process files, logs, and data through Claude for analysis.

Log Analysis:

bash

# Analyze error logs
tail -1000 /var/log/app/error.log | claude -p "summarize these errors and suggest fixes"

# Find patterns in access logs
cat access.log | claude -p "identify suspicious access patterns"

# Analyze git history
git log --oneline -50 | claude -p "summarize recent development activity"

Code Processing:

bash

# Review a specific file
cat src/auth.ts | claude -p "review this authentication code for security issues"

# Generate documentation
cat src/api/*.ts | claude -p "generate API documentation in markdown"

# Find TODOs and prioritize
grep -r "TODO" src/ | claude -p "prioritize these TODOs by importance"

3. Multi-Session Workflows

Manage complex projects with multiple conversation threads.

bash

# Start a feature branch session
claude -r "feature-auth" "let's implement user authentication"

# Later, continue the session
claude -r "feature-auth" "add password reset functionality"

# Fork to try an alternative approach
claude --resume feature-auth --fork-session "try OAuth instead"

# Switch between different feature sessions
claude -r "feature-payments" "continue with Stripe integration"

4. Custom Agent Configuration

Define specialized agents for your team's workflows.

bash

# Save agents config to file
cat > ~/.claude/agents.json << 'EOF'
{
  "reviewer": {
    "description": "Code reviewer for PR reviews",
    "prompt": "Review code for quality, security, and maintainability.",
    "model": "opus"
  },
  "documenter": {
    "description": "Documentation specialist",
    "prompt": "Generate clear, comprehensive documentation.",
    "model": "sonnet"
  },
  "refactorer": {
    "description": "Code refactoring expert",
    "prompt": "Suggest and implement clean code refactoring.",
    "tools": ["Read", "Edit", "Glob"]
  }
}
EOF

# Use agents in session
claude --agents "$(cat ~/.claude/agents.json)" "review the auth module"

5. Batch Processing

Process multiple queries with consistent settings.

bash

# Process multiple files
for file in src/*.ts; do
  echo "Processing $file..."
  claude -p --model haiku "summarize this file: $(cat $file)" >> summaries.md
done

# Batch code review
find src -name "*.py" -exec sh -c '
  echo "## $1" >> review.md
  cat "$1" | claude -p "brief code review" >> review.md
' _ {} \;

# Generate tests for all modules
for module in $(ls src/modules/); do
  claude -p "generate unit tests for src/modules/$module" > "tests/$module.test.ts"
done

6. Security-Conscious Development

Use permission controls for safe operation.

bash

# Read-only security audit
claude --permission-mode plan \
  --tools "Read,Grep,Glob" \
  "audit this codebase for security vulnerabilities"

# Block dangerous commands
claude --disallowedTools "Bash(rm:*)" "Bash(curl:*)" "Bash(wget:*)" \
  "help me clean up this project"

# Restricted automation
claude -p --max-turns 2 \
  --allowedTools "Read" "Glob" \
  "find all hardcoded credentials"

7. JSON API Integration

Use Claude as a programmable API for your tools with jq parsing.

bash

# Get structured analysis
claude -p --output-format json \
  --json-schema '{"type":"object","properties":{"functions":{"type":"array"},"complexity":{"type":"string"}}}' \
  "analyze main.py and return function list with complexity rating"

# Integrate with jq for processing
claude -p --output-format json "list all API endpoints" | jq '.endpoints[]'

# Use in scripts
RESULT=$(claude -p --output-format json "is this code secure? answer with {secure: boolean, issues: []}" < code.py)
if echo "$RESULT" | jq -e '.secure == false' > /dev/null; then
  echo "Security issues found!"
  echo "$RESULT" | jq '.issues[]'
fi

jq Parsing Examples

Parse and process Claude's JSON output using jq:

bash

# Extract specific fields
claude -p --output-format json "analyze this code" | jq '.result'

# Filter array elements
claude -p --output-format json "list issues" | jq -r '.issues[] | select(.severity=="high")'

# Extract multiple fields
claude -p --output-format json "describe the project" | jq -r '.{name, version, description}'

# Convert to CSV
claude -p --output-format json "list functions" | jq -r '.functions[] | [.name, .lineCount] | @csv'

# Conditional processing
claude -p --output-format json "check security" | jq 'if .vulnerabilities | length > 0 then "UNSAFE" else "SAFE" end'

# Extract nested values
claude -p --output-format json "analyze performance" | jq '.metrics.cpu.usage'

# Process entire array
claude -p --output-format json "find todos" | jq '.todos | length'

# Transform output
claude -p --output-format json "list improvements" | jq 'map({title: .title, priority: .priority})'

Models

Claude Code supports multiple models with different capabilities:

Model	ID	Context Window	Notes
Opus 4.7	`claude-opus-4-7`	1M tokens (1M context fix landed in v2.1.117)	Most capable, adaptive effort levels; `xhigh` is the default effort on Claude Code since Opus 4.7 launch (2026-04-16)
Sonnet 4.6	`claude-sonnet-4-6`	1M tokens	Balanced speed and capability; default effort for Pro/Max subscribers raised from `medium` to `high` in v2.1.117
Haiku 4.5	`claude-haiku-4-5`	1M tokens	Fastest, best for quick tasks

Model Selection

bash

# Use short names
claude --model opus "complex architectural review"
claude --model sonnet "implement this feature"
claude --model haiku -p "format this JSON"

# Use opusplan alias (Opus plans, Sonnet executes)
claude --model opusplan "design and implement the API"

# Toggle fast mode during session
/fast

Effort Levels (Opus 4.7)

Opus 4.7 supports adaptive reasoning with effort levels, ordered from lightest to heaviest: low (○), medium (◐), high (●), xhigh (default on Claude Code since Opus 4.7 launch, 2026-04-16), and max (Opus 4.7 only). On Opus 4.6 / Sonnet 4.6, the default effort for Pro/Max subscribers was raised from medium to high in v2.1.117.

bash

# Set effort level via CLI flag
claude --effort xhigh "complex review"

# Set effort level via slash command
/effort xhigh

# Set effort level via environment variable
export CLAUDE_CODE_EFFORT_LEVEL=xhigh   # low, medium, high, xhigh (default on Opus 4.7), or max (Opus 4.7 only)

The "ultrathink" keyword in prompts activates deep reasoning. The max effort level is exclusive to Opus 4.7.

Key Environment Variables

Variable	Description
`ANTHROPIC_API_KEY`	API key for authentication
`ANTHROPIC_MODEL`	Override default model
`ANTHROPIC_CUSTOM_MODEL_OPTION`	Custom model option for API
`ANTHROPIC_DEFAULT_OPUS_MODEL`	Override default Opus model ID
`ANTHROPIC_DEFAULT_SONNET_MODEL`	Override default Sonnet model ID
`ANTHROPIC_DEFAULT_HAIKU_MODEL`	Override default Haiku model ID
`MAX_THINKING_TOKENS`	Set extended thinking token budget
`CLAUDE_CODE_EFFORT_LEVEL`	Set effort level (`low`/`medium`/`high`/`xhigh`/`max`) — `xhigh` is the default on Opus 4.7; `max` is Opus 4.7 only
`CLAUDE_CODE_SIMPLE`	Minimal mode, set by `--bare` flag
`CLAUDE_CODE_DISABLE_AUTO_MEMORY`	Disable automatic CLAUDE.md updates
`CLAUDE_CODE_DISABLE_BACKGROUND_TASKS`	Disable background task execution
`CLAUDE_CODE_DISABLE_CRON`	Disable scheduled/cron tasks
`CLAUDE_CODE_DISABLE_GIT_INSTRUCTIONS`	Disable git-related instructions
`CLAUDE_CODE_DISABLE_TERMINAL_TITLE`	Disable terminal title updates
`CLAUDE_CODE_DISABLE_1M_CONTEXT`	Disable 1M token context window
`CLAUDE_CODE_DISABLE_NONSTREAMING_FALLBACK`	Disable non-streaming fallback
`CLAUDE_CODE_ENABLE_TASKS`	Enable task list feature
`CLAUDE_CODE_TASK_LIST_ID`	Named task directory shared across sessions
`CLAUDE_CODE_ENABLE_PROMPT_SUGGESTION`	Toggle prompt suggestions (`true`/`false`)
`CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS`	Enable experimental agent teams
`CLAUDE_CODE_NEW_INIT`	Use new initialization flow
`CLAUDE_CODE_SUBAGENT_MODEL`	Model for subagent execution
`CLAUDE_CODE_PLUGIN_SEED_DIR`	Directory for plugin seed files
`CLAUDE_CODE_SUBPROCESS_ENV_SCRUB`	Env vars to scrub from subprocesses
`CLAUDE_AUTOCOMPACT_PCT_OVERRIDE`	Override auto-compaction percentage
`CLAUDE_STREAM_IDLE_TIMEOUT_MS`	Stream idle timeout in milliseconds
`SLASH_COMMAND_TOOL_CHAR_BUDGET`	Character budget for slash command tools
`ENABLE_TOOL_SEARCH`	Enable tool search capability
`MAX_MCP_OUTPUT_TOKENS`	Maximum tokens for MCP tool output
`CLAUDE_CODE_PERFORCE_MODE`	Set to `1` to enable Perforce mode — treats files as read-only by default (for Perforce/P4 version control workflows) (added v2.1.98)
`DISABLE_UPDATES`	Blocks all update paths including manual `claude update`. Stricter than `DISABLE_AUTOUPDATER`, which only blocks the background autoupdater (v2.1.118+)
`CLAUDE_CODE_HIDE_CWD`	When set to `1`, hides the current working directory in the startup logo (privacy / screen-share use) (v2.1.119+)
`CLAUDE_CODE_FORK_SUBAGENT`	Set to `1` to enable forked subagents on external builds (Bedrock, Vertex, Foundry). No effect on Anthropic API where forked subagents are GA (v2.1.117+)
`OTEL_LOG_TOOL_DETAILS`	Set to `1` to unredact custom and MCP command names in OpenTelemetry events (v2.1.117+). Redaction remains the default.
`ANTHROPIC_BEDROCK_SERVICE_TIER`	Selects the Bedrock service tier: `default`, `flex`, or `priority` (v2.1.122+)
`AI_AGENT`	Set automatically on subprocesses so external CLIs (e.g., `gh`) can attribute traffic to Claude Code (v2.1.120+)

ENABLE_TOOL_SEARCH on Vertex AI (v2.1.119+): Tool search is disabled by default on Google Cloud Vertex AI deployments. Users who want the tool-search capability on Vertex must explicitly opt in with export ENABLE_TOOL_SEARCH=true. On direct Anthropic API it remains enabled by default.

Quick Reference

Most Common Commands

bash

# Interactive session
claude

# Quick question
claude -p "how do I..."

# Continue conversation
claude -c

# Process a file
cat file.py | claude -p "review this"

# JSON output for scripts
claude -p --output-format json "query"

Flag Combinations

Use Case	Command
Quick code review	`cat file
Structured output	`claude -p --output-format json "query"`
Safe exploration	`claude --permission-mode plan`
Autonomous with safety	`claude --enable-auto-mode --permission-mode auto`
CI/CD integration	`claude -p --max-turns 3 --output-format json`
Resume work	`claude -r "session-name"`
Custom model	`claude --model opus "complex task"`
Minimal mode	`claude --bare "quick query"`
Budget-capped run	`claude -p --max-budget-usd 2.00 "analyze code"`

Troubleshooting

Command Not Found

Problem: claude: command not found

Solutions:

Install Claude Code: npm install -g @anthropic-ai/claude-code
Check PATH includes npm global bin directory
Try running with full path: npx claude

API Key Issues

Problem: Authentication failed

Solutions:

Set API key: export ANTHROPIC_API_KEY=your-key
Check key is valid and has sufficient credits
Verify key permissions for the model requested

Session Not Found

Problem: Cannot resume session

Solutions:

List available sessions to find correct name/ID
Sessions may expire after period of inactivity
Use -c to continue most recent session

Output Format Issues

Problem: JSON output is malformed

Solutions:

Use --json-schema to enforce structure
Add explicit JSON instructions in prompt
Use --output-format json (not just asking for JSON in prompt)

Permission Denied

Problem: Tool execution blocked

Solutions:

Check --permission-mode setting
Review --allowedTools and --disallowedTools flags
Use --dangerously-skip-permissions for automation (with caution)

Additional Resources

Official CLI Reference - Complete command reference
Headless Mode Documentation - Automated execution
Slash Commands - Custom shortcuts within Claude
Memory Guide - Persistent context via CLAUDE.md
MCP Protocol - External tool integrations
Advanced Features - Planning mode, extended thinking
Subagents Guide - Delegated task execution

Part of the Claude How To guide series

Last Updated: May 2, 2026 Claude Code Version: 2.1.126 Sources:

CLI Reference ​

Overview ​

Architecture ​

Runtime & Packaging ​

CLI Commands ​

Core Flags ​

Interactive vs Print Mode ​

Model & Configuration ​

Model Selection Examples ​

System Prompt Customization ​

System Prompt Examples ​

System Prompt Flags Comparison ​

Tool & Permission Management ​

Permission Examples ​

Output & Format ​

Output Format Examples ​

Workspace & Directory ​

Multi-Directory Example ​

MCP Configuration ​

MCP Examples ​

Session Management ​

Session Examples ​

Session Fork ​

Project State Cleanup (v2.1.126+) ​

Advanced Features ​

Platform & Theme Notes (v2.1.112) ​

Advanced Examples ​

Agents Configuration ​

Agents JSON Format ​

Complete Agents Example ​

Agents Command Examples ​

Agent Priority ​

High-Value Use Cases ​

1. CI/CD Integration ​

2. Script Piping ​

3. Multi-Session Workflows ​

4. Custom Agent Configuration ​

5. Batch Processing ​

6. Security-Conscious Development ​

7. JSON API Integration ​

jq Parsing Examples ​

Models ​

Model Selection ​

Effort Levels (Opus 4.7) ​

Key Environment Variables ​

Quick Reference ​

Most Common Commands ​

Flag Combinations ​

Troubleshooting ​

Command Not Found ​

API Key Issues ​

Session Not Found ​

Output Format Issues ​

Permission Denied ​

Additional Resources ​

CLI Reference

Overview

Architecture

Runtime & Packaging

CLI Commands

Core Flags

Interactive vs Print Mode

Model & Configuration

Model Selection Examples

System Prompt Customization

System Prompt Examples

System Prompt Flags Comparison

Tool & Permission Management

Permission Examples

Output & Format

Output Format Examples

Workspace & Directory

Multi-Directory Example

MCP Configuration

MCP Examples

Session Management

Session Examples

Session Fork

Project State Cleanup (v2.1.126+)

Advanced Features

Platform & Theme Notes (v2.1.112)

Advanced Examples

Agents Configuration

Agents JSON Format

Complete Agents Example

Agents Command Examples

Agent Priority

High-Value Use Cases

1. CI/CD Integration

2. Script Piping

3. Multi-Session Workflows

4. Custom Agent Configuration

5. Batch Processing

6. Security-Conscious Development

7. JSON API Integration

jq Parsing Examples

Models

Model Selection

Effort Levels (Opus 4.7)

Key Environment Variables

Quick Reference

Most Common Commands

Flag Combinations

Troubleshooting

Command Not Found

API Key Issues

Session Not Found

Output Format Issues

Permission Denied

Additional Resources