# Entr

> Run arbitrary commands when files change. Useful for watching files and triggering builds or tests.

- Skill: `kbarbel640-del/entr` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add kbarbel640-del/entr`
- Raw SKILL.md: https://api.skillmd.com/api/skills/kbarbel640-del/entr/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: kbarbel640-del (https://skillmd.com/u/kbarbel640-del)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/kbarbel640-del/entr

---


# entr (Event Notify Test Runner)

A utility for running arbitrary commands when files change.

## Usage

`entr` takes a list of filenames from standard input and executes the utility specified as the first argument.

### Syntax
```bash
<file_listing_command> | entr <utility> [arguments]
```

### Options
- `-c`: Clear the screen before invoking the utility.
- `-r`: Reload a persistent child process (e.g., a server).
- `-s`: Evaluate the first argument using the interpreter specified by `SHELL`.

## Examples

**Rebuild project when sources change:**
```bash
find src/ -name "*.c" | entr make
```

**Run tests when JS files change:**
```bash
git ls-files | grep '\.js$' | entr npm test
```

**Auto-reload a Node server:**
```bash
ls *.js | entr -r node app.js
```

## Agent Notes
`entr` blocks the terminal. When using it as an agent:
1. Use `process` tool to run it in the background if you need to do other things.
2. Or use it for a quick "watch mode" session where you intend to monitor output for a while.