> For the complete documentation index, see [llms.txt](https://docs.pentaho.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview/hadoop-file-input-cp-main-page/select-an-engine-hadoop-file-input/using-the-hadoop-file-input-step-on-the-pentaho-engine-cp/options-hadoop-file-input-reuse/file-tab-hadoop-file-input-kettle/selecting-a-file-using-regular-expressions-kettle.md).

# Selecting a file using regular expressions

Use the **Wildcard (RegExp)** field in the **File** tab to search for files by wildcard in the form of a regular expression. Regular expressions are more sophisticated than using `*` and `?` wildcards. This table describes several examples of regular expressions.

| File Name | Regular Expression          | Files Selected                                                                                  |
| --------- | --------------------------- | ----------------------------------------------------------------------------------------------- |
| `/dirA/`  | `.userdata.\.txt`           | Find all files in `/dirA/` with names containing userdata and ending with `.txt`                |
| `/dirB/`  | `AAA.\*`                    | Find all files in `/dirB/` with names that start with `AAA`                                     |
| `/dirC/`  | `\[ENG:A-Z\]\[ENG:0-9\].\*` | Find all files in `/dirC/` with names that start with a capital and followed by a digit (A0-Z9) |


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

```
GET https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview/hadoop-file-input-cp-main-page/select-an-engine-hadoop-file-input/using-the-hadoop-file-input-step-on-the-pentaho-engine-cp/options-hadoop-file-input-reuse/file-tab-hadoop-file-input-kettle/selecting-a-file-using-regular-expressions-kettle.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.