> For the complete documentation index, see [llms.txt](https://sevenval.gitbook.io/flat/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sevenval.gitbook.io/flat/develop/reference/actions/regex.md).

# regex Action

## Syntax

Attributes:

* `pattern="..."` to define the search expression including delimiter and modifier (required)
* `replace="..."` to set the replacement text (required)
* `in="..."` to define the input location (optional, default is `fit://request/content`)
* `out="..."` to define the output location (optional, default is `fit://request/content`)

```markup
<regex pattern="#abc$#" replace="123" />
<regex in="$test" out="$test" pattern="/foo/i" replace="bar" />
```

## Usage

The `regex` action works on text content only. However, if the input is a DOM, it is automatically serialized into a string for the action to work. The output of this action is always a string.

The replacement is carried out with the [PCRE](https://www.pcre.org/) regular expression library.

## Example

This example converts a date of the form `YYYY-MM-DD` into `DD.MM.YY`:

```markup
<regex pattern="|20([012]\d)-(\d\d)-(\d\d)|" replace="$3.$2.$1"/>
```

## Errors

If the `pattern` does not compile, the request will terminate with an error.

It is not an error if the `pattern` does not match or the replacement is empty.