# Using entr to react to file changes

[`entr`](https://github.com/eradman/entr) is "A utility for running arbitrary commands when files change". It's available on both Linux and MacOS.

```bash
# Run make build when source files change
find . -type f -name '*.c' | entr make build
```

`/_` is a shorthand that is replaced with the absolute path of the first file to trigger an event.

```bash
# Run my_script.sh on save
echo my_script.sh | entr /_
```


---

# 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://notes.eliasnorrby.com/tools/using-entr-to-react-to-file-changes.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.