# secondary\_file

![](/files/-LWNPNeEkhSLIRkULLY1)

The `out_secondary_file` Output plugin writes chunks to files. This plugin is similar to `out_file` but this is for `<secondary>` use-case.

NOTE: Do not use this plugin for the primary plugin.

`out_secondary_file` is included in Fluentd's core.

## Example Configuration

```
<match pattern>
  @type forward
  # ...
  <secondary>
    @type secondary_file
    directory /var/log/fluentd/error
  </secondary>
</match>
```

With this configuration, failed buffer chunks are saved into `/var/log/fluentd/error/dump.bin.N`, `N` is 0-origin incremental number.

Please see the [Configuration File](/configuration/config-file.md) article for the basic structure and syntax of the configuration file.

## Plugin Helpers

No helpers.

## Parameters

[Common Parameters](/configuration/plugin-common-parameters.md)

### `@type` (required)

The value must be `secondary_file`.

### `directory`

| type   | default            | version |
| ------ | ------------------ | ------- |
| string | required parameter | 1.0.0   |

The directory path of the output file. Received buffer chunks are saved in this directory.

```
<secondary>
  @type secondary_file
  directory /var/log/fluentd/error
</secondary>
```

### `basename`

| type   | default  | version |
| ------ | -------- | ------- |
| string | dump.bin | 1.0.0   |

The basename of the output file. You can use `${chunk_id}` placeholder to identify the original chunk.

```
<secondary>
  @type secondary_file
  directory /var/log/fluentd/error
  basename dump.${chunk_id}
</secondary>
```

The output path would be:

```
# 59c278456e74a22dc594b06a7d4247c4 is chunk id
/var/log/fluentd/error/dump.59c278456e74a22dc594b06a7d4247c4.0
```

### `append`

| type | default | version |
| ---- | ------- | ------- |
| bool | false   | 1.0.0   |

Determines that the received chunk is appended to an existing file or not. By default, it is not appended and each chunk is flushed to a different path:

```
# append false
dump.bin.0
dump.bin.1
dump.bin.2
...
dump.bin.N
```

This makes parallel file processing easy. But if you want to disable this behavior, you can disable it by setting `append true`:

```
# append true
dump.bin
```

### `compress`

| type | default | version |
| ---- | ------- | ------- |
| enum | text    | 1.0.0   |

Supported compress types: `text`, `gzip`

When `gzip` is specified, `.gz` is automatically added to the output file path as its suffix.

## How to resend secondary file

The secondary file can be resend by `fluent-cat` command.

Here is the example to resend `dump.bin.0` to `127.0.0.1:24224` using `fluent-cat`.

```
$ cat /path/to/dump.bin.0 | fluent-cat --format msgpack  --host 127.0.0.1 --port 24224 TAG
```

See [fluent-cat](/deployment/command-line-option.md#fluent-cat) command line option about details.

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is an open-source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.fluentd.org/output/secondary_file.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.