Lumos

Lumos is a command‑line utility to query and set the brightness of both internal backlight panels and external monitors supporting DDC/CI. It offers machine‑readable and human‑readable outputs, step adjustments, direct percentage or raw value setting, on‑screen popups, and persistent device selection.

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Features

• Internal backlight control via /sys/class/backlight/*
• External DDC/CI control over /dev/i2c-* or /dev/drm_dp_aux*
• Machine‑readable (-m) and human‑readable (-r) output
• Step adjust brightness up/down by 10% (-a up|down)
• Set brightness by percent or raw value (-s VALUE, -R)
• On‑screen popup via X11 (suppressed with -n)
• Persist default backlight interface (-P)
• Profiles & presets skeleton support (--profile-new, --profile-load)
• Udev rule installation (-U, --setup) to allow non-root use

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Installation

Prerequisites

Make sure you have these packages installed:

• GNU C toolchain: gcc, make
• pkg-config
• X11 development headers: libx11-dev
• I²C‑dev development headers: libi2c-dev
• Linux kernel headers (for /dev/i2c-* support)
• (optional) DRM development headers: libdrm-dev (for /dev/drm_dp_aux* nodes)
• Build essentials: build-essential

On Debian/Ubuntu:

sudo apt update
sudo apt install build-essential pkg-config libx11-dev libi2c-dev linux-headers-$(uname -r) libdrm-dev

Build & Install

git clone https://github.com/yourusername/lumos.git
cd lumos
make
sudo make install

This will install:

• BINARY → /usr/local/bin/lumos
• HEADER → /usr/local/include/brightness.h /usr/local/include/udev_setup.h
  • This is a comment in the makefile. It no longer does this.
  • This is for future API support through other programs.
• MANPAGE → /usr/local/share/man/man1/lumos.1

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Usage

$ lumos --help
Usage: lumos [options]
  -m, --machine-readable       print raw brightness value
  -r, --human-readable        print raw & percent nicely
  -a, --adjust <up|down>      step adjust by 10%
  -s, --set <value>           set brightness (percent)
  -R, --raw                   treat -s value as raw
  -n, --nodisplay             suppress X11 popup
  -d, --device <iface>        internal backlight interface
  -P, --persist-device        save internal interface to config
  -x, --external <connector>  DDC/CI external monitor (e.g. HDMI-1)
  --profile-new <name>        create profile (skeleton)
  --profile-load <name>       load profile (skeleton)
  -h, --help                  this help

Examples

• Show internal brightness

  lumos -r
  # Internal backlight: raw=450, max=1000, percent=45%

• Step external HDMI‑1 down

  lumos -x HDMI-1 -a down

• Set external monitor to 70%

  lumos -x HDMI-1 -s 70

• Save preferred internal interface

  lumos -d intel_backlight -P

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Configuration

Lumos stores your chosen internal backlight interface in:

~/.config/lumos/config

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Development

1. Clone the repo
2. Edit src/ and include/ as needed
3. make && sudo make install
4. Submit pull requests or open issues!

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License

This project is released under the MIT License. See LICENSE for details.