> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-mintlify-3a82795f.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Executable File dictionary source

> Configure an executable file as a dictionary source in ClickHouse.

Working with executable files depends on [how the dictionary is stored in memory](/reference/statements/create/dictionary/layouts/overview). If the dictionary is stored using `cache` and `complex_key_cache`, ClickHouse requests the necessary keys by sending a request to the executable file's STDIN. Otherwise, ClickHouse starts the executable file and treats its output as dictionary data.

Example of settings:

<Tabs>
  <Tab title="DDL">
    ```sql theme={null}
    SOURCE(EXECUTABLE(
        command 'cat /opt/dictionaries/os.tsv'
        format 'TabSeparated'
        implicit_key false
    ))
    ```
  </Tab>

  <Tab title="Configuration file">
    ```xml theme={null}
    <source>
        <executable>
            <command>cat /opt/dictionaries/os.tsv</command>
            <format>TabSeparated</format>
            <implicit_key>false</implicit_key>
        </executable>
    </source>
    ```
  </Tab>
</Tabs>

Setting fields:

| Setting                       | Description                                                                                                                                                                                                                                                                                                                                                                                                         |
| ----------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `command`                     | The absolute path to the executable file, or the file name (if the command's directory is in the `PATH`).                                                                                                                                                                                                                                                                                                           |
| `format`                      | The file format. All the formats described in [Formats](/reference/formats) are supported.                                                                                                                                                                                                                                                                                                                          |
| `command_termination_timeout` | The executable script should contain a main read-write loop. After the dictionary is destroyed, the pipe is closed, and the executable file will have `command_termination_timeout` seconds to shutdown before ClickHouse will send a SIGTERM signal to the child process. Specified in seconds. Default value is `10`. Optional.                                                                                   |
| `command_read_timeout`        | Timeout for reading data from command stdout in milliseconds. Default value `10000`. Optional.                                                                                                                                                                                                                                                                                                                      |
| `command_write_timeout`       | Timeout for writing data to command stdin in milliseconds. Default value `10000`. Optional.                                                                                                                                                                                                                                                                                                                         |
| `implicit_key`                | The executable source file can return only values, and the correspondence to the requested keys is determined implicitly by the order of rows in the result. Default value is `false`.                                                                                                                                                                                                                              |
| `execute_direct`              | If `execute_direct` = `1`, then `command` will be searched inside user\_scripts folder specified by [user\_scripts\_path](/reference/settings/server-settings/settings#user_scripts_path). Additional script arguments can be specified using a whitespace separator. Example: `script_name arg1 arg2`. If `execute_direct` = `0`, `command` is passed as argument for `bin/sh -c`. Default value is `0`. Optional. |
| `send_chunk_header`           | Controls whether to send row count before sending a chunk of data to process. Default value is `false`. Optional.                                                                                                                                                                                                                                                                                                   |

That dictionary source can be configured only via XML configuration. Creating dictionaries with executable source via DDL is disabled; otherwise, the DB user would be able to execute arbitrary binaries on the ClickHouse node.