KLC – Elgato Key Light Control Script

A simple, low-dependency Bash script for controlling Elgato Key Lights over the network using their HTTP API.

📋 Description

klc is a CLI tool for discovering, querying, and controlling Elgato Key Lights using their native HTTP interface. It supports toggling the light, adjusting brightness, and setting the color temperature — all without requiring any heavy frameworks or package managers.

💡 Why This Script?

Elgato Key Lights expose an unauthenticated HTTP API (see here), and many tools already exist to interact with them.

However:

• One tool I tried offered a GUI but outright refused to work.
• Another was written in Go and brought in a full framework just to send a few HTTP requests — the logic was completely obscured.
• A Python tool required a pip install and came with a handful of dependencies.
• A seemingly promising Bash project prioritized output formatters (JSON, XML, YAML, ...) over actually turning the light on.

So I wrote my own — just a clean Bash script with:

• ✅ No dependencies beyond avahi-browse, curl, and jq
• ✅ No installers, no GUIs, no package managers
• ✅ Clear, readable logic

✨ Features

• 🕵️‍♂️ Auto-discovers the first available Elgato Key Light on the network via avahi
• 🧠 Caches the discovered IP for faster reuse on subsequent calls
• 💡 Turns light on/off
• 🔆 Adjusts brightness (NUM, increase, decrease, min, max)
• 🌡️ Adjusts temperature in either Mired or Kelvin units
• ⚡ Accepts abbreviated commands (e.g. br, temp, inc, dec)

🚀 Usage

$ klc on
$ klc off
$ klc status
$ 
$ klc brightness 75         # brightness to 75%
$ klc brightness increase
$ klc brightness decrease
$ klc brightness min
$ klc brightness max
$ 
$ klc temperature 5000      # Kelvin input
$ klc temperature 200       # Mired input
$ klc temperature increase
$ klc temperature decrease
$ klc temperature min
$ klc temperature max

You can abbreviate most commands:

• status: s, st
• brightness: b, br, bright
• temperature: t, te, temp
• increase: i, inc
• decrease: d, dec

⚠️ Caveats

• 🧭 The script always uses the first discovered device via Avahi.
• 🎚️ Temperature values can be entered as Kelvin or Mired. Conversion rounding is approximate but visually negligible.
• ➕ Only one command can be executed per call (e.g., you can't change brightness and temperature at once).

📦 Requirements

• bash
• avahi-browse (for discovery)
• curl (for HTTP requests)
• jq (for parsing JSON)

All are commonly available on modern Linux distributions and macOS with Homebrew.

📁 Installation

Just clone or copy the script. No build, no install, no hassle.

$ chmod +x klc
$ ./klc on

For better calling convenience, you may choose to append the script's location to your PATH or copy it into your executables directory:

$ PATH=$(readlink -f .):$PATH   # Option 1: temporary (for this shell session only)
$ cp klc ~/.local/bin           # Option 2: permanent (path may be different on your system)
$ sudo cp klc /usr/bin          # Option 3: permanent, system-wide (if you really want to)

🛠️ Contributions

Contributions are welcome.

📄 License

MIT — Do what you want, but don't blame me if your lights go disco mode. 😉