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Run Claude Code programmatically

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Documentation Index

Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt Use this file to discover all available pages before exploring further.

Run Claude Code programmatically

Use the Agent SDK to run Claude Code programmatically from the CLI, Python, or TypeScript.

The Agent SDK gives you the same tools, agent loop, and context management that power Claude Code. It's available as a CLI for scripts and CI/CD, or as Python and TypeScript packages for full programmatic control.

The CLI was previously called "headless mode." The -p flag and all CLI options work the same way.

To run Claude Code programmatically from the CLI, pass -p with your prompt and any CLI options:

```bash theme={null} claude -p "Find and fix the bug in auth.py" --allowedTools "Read,Edit,Bash"


This page covers using the Agent SDK via the CLI (`claude -p`). For the Python and TypeScript SDK packages with structured outputs, tool approval callbacks, and native message objects, see the [full Agent SDK documentation](https://code.claude.com/en/agent-sdk/overview).

## Basic usage

Add the `-p` (or `--print`) flag to any `claude` command to run it non-interactively. All [CLI options](https://code.claude.com/en/cli-reference) work with `-p`, including:

* `--continue` for [continuing conversations](#continue-conversations)
* `--allowedTools` for [auto-approving tools](#auto-approve-tools)
* `--output-format` for [structured output](#get-structured-output)

This example asks Claude a question about your codebase and prints the response:

```bash theme={null}
claude -p "What does the auth module do?"

Start faster with bare mode

Add --bare to reduce startup time by skipping auto-discovery of hooks, skills, plugins, MCP servers, auto memory, and CLAUDE.md. Without it, claude -p loads the same context an interactive session would, including anything configured in the working directory or ~/.claude.

Bare mode is useful for CI and scripts where you need the same result on every machine. A hook in a teammate's ~/.claude or an MCP server in the project's .mcp.json won't run, because bare mode never reads them. Only flags you pass explicitly take effect.

This example runs a one-off summarize task in bare mode and pre-approves the Read tool so the call completes without a permission prompt:

```bash theme={null} claude --bare -p "Summarize this file" --allowedTools "Read"


In bare mode Claude has access to the Bash, file read, and file edit tools. Pass any context you need with a flag:

| To load                 | Use                                                     |
| ----------------------- | ------------------------------------------------------- |
| System prompt additions | `--append-system-prompt`, `--append-system-prompt-file` |
| Settings                | `--settings <file-or-json>`                             |
| MCP servers             | `--mcp-config <file-or-json>`                           |
| Custom agents           | `--agents <json>`                                       |
| A plugin directory      | `--plugin-dir <path>`                                   |

Bare mode skips OAuth and keychain reads. Anthropic authentication must come from `ANTHROPIC_API_KEY` or an `apiKeyHelper` in the JSON passed to `--settings`. Bedrock, Vertex, and Foundry use their usual provider credentials.

<Note>
  `--bare` is the recommended mode for scripted and SDK calls, and will become the default for `-p` in a future release.
</Note>

## Examples

These examples highlight common CLI patterns. For CI and other scripted calls, add [`--bare`](#start-faster-with-bare-mode) so they don't pick up whatever happens to be configured locally.

### Get structured output

Use `--output-format` to control how responses are returned:

* `text` (default): plain text output
* `json`: structured JSON with result, session ID, and metadata
* `stream-json`: newline-delimited JSON for real-time streaming

This example returns a project summary as JSON with session metadata, with the text result in the `result` field:

```bash theme={null}
claude -p "Summarize this project" --output-format json

To get output conforming to a specific schema, use --output-format json with --json-schema and a JSON Schema definition. The response includes metadata about the request (session ID, usage, etc.) with the structured output in the structured_output field.

This example extracts function names and returns them as an array of strings:

```bash theme={null} claude -p "Extract the main function names from auth.py" \ --output-format json \ --json-schema '{"type":"object","properties":{"functions":{"type":"array","items":{"type":"string"}}},"required":["functions"]}'


<Tip>
  Use a tool like [jq](https://jqlang.github.io/jq/) to parse the response and extract specific fields:

  ```bash theme={null}
  # Extract the text result
  claude -p "Summarize this project" --output-format json | jq -r '.result'

  # Extract structured output
  claude -p "Extract function names from auth.py" \
    --output-format json \
    --json-schema '{"type":"object","properties":{"functions":{"type":"array","items":{"type":"string"}}},"required":["functions"]}' \
    | jq '.structured_output'
  ```
</Tip>

### Stream responses

Use `--output-format stream-json` with `--verbose` and `--include-partial-messages` to receive tokens as they're generated. Each line is a JSON object representing an event:

```bash theme={null}
claude -p "Explain recursion" --output-format stream-json --verbose --include-partial-messages

The following example uses jq to filter for text deltas and display just the streaming text. The -r flag outputs raw strings (no quotes) and -j joins without newlines so tokens stream continuously:

```bash theme={null} claude -p "Write a poem" --output-format stream-json --verbose --include-partial-messages | \ jq -rj 'select(.type == "stream_event" and .event.delta.type? == "text_delta") | .event.delta.text'


When an API request fails with a retryable error, Claude Code emits a `system/api_retry` event before retrying. You can use this to surface retry progress or implement custom backoff logic.

| Field            | Type            | Description                                                                                                                                  |
| ---------------- | --------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| `type`           | `"system"`      | message type                                                                                                                                 |
| `subtype`        | `"api_retry"`   | identifies this as a retry event                                                                                                             |
| `attempt`        | integer         | current attempt number, starting at 1                                                                                                        |
| `max_retries`    | integer         | total retries permitted                                                                                                                      |
| `retry_delay_ms` | integer         | milliseconds until the next attempt                                                                                                          |
| `error_status`   | integer or null | HTTP status code, or `null` for connection errors with no HTTP response                                                                      |
| `error`          | string          | error category: `authentication_failed`, `billing_error`, `rate_limit`, `invalid_request`, `server_error`, `max_output_tokens`, or `unknown` |
| `uuid`           | string          | unique event identifier                                                                                                                      |
| `session_id`     | string          | session the event belongs to                                                                                                                 |

The `system/init` event reports session metadata including the model, tools, MCP servers, and loaded plugins. It is the first event in the stream unless [`CLAUDE_CODE_SYNC_PLUGIN_INSTALL`](https://code.claude.com/en/env-vars) is set, in which case `plugin_install` events precede it. Use the plugin fields to fail CI when a plugin did not load:

| Field           | Type  | Description                                                                                                                                                                                                       |
| --------------- | ----- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `plugins`       | array | plugins that loaded successfully, each with `name` and `path`                                                                                                                                                     |
| `plugin_errors` | array | plugin load-time errors such as an unsatisfied dependency version, each with `plugin`, `type`, and `message`. Affected plugins are demoted and absent from `plugins`. The key is omitted when there are no errors |

When [`CLAUDE_CODE_SYNC_PLUGIN_INSTALL`](https://code.claude.com/en/env-vars) is set, Claude Code emits `system/plugin_install` events while marketplace plugins install before the first turn. Use these to surface install progress in your own UI.

| Field        | Type                                                     | Description                                                                                                    |
| ------------ | -------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------- |
| `type`       | `"system"`                                               | message type                                                                                                   |
| `subtype`    | `"plugin_install"`                                       | identifies this as a plugin install event                                                                      |
| `status`     | `"started"`, `"installed"`, `"failed"`, or `"completed"` | `started` and `completed` bracket the overall install; `installed` and `failed` report individual marketplaces |
| `name`       | string, optional                                         | marketplace name, present on `installed` and `failed`                                                          |
| `error`      | string, optional                                         | failure message, present on `failed`                                                                           |
| `uuid`       | string                                                   | unique event identifier                                                                                        |
| `session_id` | string                                                   | session the event belongs to                                                                                   |

For programmatic streaming with callbacks and message objects, see [Stream responses in real-time](https://code.claude.com/en/agent-sdk/streaming-output) in the Agent SDK documentation.

### Auto-approve tools

Use `--allowedTools` to let Claude use certain tools without prompting. This example runs a test suite and fixes failures, allowing Claude to execute Bash commands and read/edit files without asking for permission:

```bash theme={null}
claude -p "Run the test suite and fix any failures" \
  --allowedTools "Bash,Read,Edit"

To set a baseline for the whole session instead of listing individual tools, pass a permission mode. dontAsk denies anything not in your permissions.allow rules or the read-only command set, which is useful for locked-down CI runs. acceptEdits lets Claude write files without prompting and also auto-approves common filesystem commands such as mkdir, touch, mv, and cp. Other shell commands and network requests still need an --allowedTools entry or a permissions.allow rule, otherwise the run aborts when one is attempted:

```bash theme={null} claude -p "Apply the lint fixes" --permission-mode acceptEdits


### Create a commit

This example reviews staged changes and creates a commit with an appropriate message:

```bash theme={null}
claude -p "Look at my staged changes and create an appropriate commit" \
  --allowedTools "Bash(git diff *),Bash(git log *),Bash(git status *),Bash(git commit *)"

The --allowedTools flag uses permission rule syntax. The trailing * enables prefix matching, so Bash(git diff *) allows any command starting with git diff. The space before * is important: without it, Bash(git diff*) would also match git diff-index.

User-invoked skills like /commit and built-in commands are only available in interactive mode. In -p mode, describe the task you want to accomplish instead.

Customize the system prompt

Use --append-system-prompt to add instructions while keeping Claude Code's default behavior. This example pipes a PR diff to Claude and instructs it to review for security vulnerabilities:

```bash theme={null} gh pr diff "$1" | claude -p \ --append-system-prompt "You are a security engineer. Review for vulnerabilities." \ --output-format json


See [system prompt flags](https://code.claude.com/en/cli-reference#system-prompt-flags) for more options including `--system-prompt` to fully replace the default prompt.

### Continue conversations

Use `--continue` to continue the most recent conversation, or `--resume` with a session ID to continue a specific conversation. This example runs a review, then sends follow-up prompts:

```bash theme={null}
# First request
claude -p "Review this codebase for performance issues"

# Continue the most recent conversation
claude -p "Now focus on the database queries" --continue
claude -p "Generate a summary of all issues found" --continue

If you're running multiple conversations, capture the session ID to resume a specific one:

bash theme={null} session_id=$(claude -p "Start a review" --output-format json | jq -r '.session_id') claude -p "Continue that review" --resume "$session_id"

Next steps