bright

A simple program to adjust brightness on linux computers using intel_backlight.

The program adjusts the brightness in percentage steps, either default (5%) or chosen value (0-50%), manipulating the sys/class/backlight/intel_backlight/brightness file directly.

The program is my final project in the Harvard course CS50x, and must be considered a basic program with basic functionality. I chose this problem for my final project to implement a brightness control on my Arch-distro running the Awesome WM, and I have created keyboard shortcuts in the rc.lua-file (the config-file of Awesome.)

The code

This program consist mainly of the bright.c file, in which all the code is contained. In addition to this the following files are included:

• README.md: This file
• LICENSE: GNU GPL v3 license for this project
• configure.ac: Config file to create the configure script for installing using autotools.
• Makefile.am: Config file for Automake, that creates the Makefile using autotools.

Future upgrades

I do not consider this program complete, even though it satisfies my current need on my computer. Here are some of the potential future upgrades for this program that I have recognized:

• The paths for the brightness and max_brightness files should be set during make searching for brightness.
• The program should reat out the max_brightness during compiling/make. (does it every run).
• Simplifying the install process by writing custom make file. Add above steps, and get rid of autotools.
• The program has not been tested on any other system, and should be to secure proper functionality.
• The default increments (5%) should be able to change permanently.

Usage

The following is the user-message when running bright -h:

Usage: bright [-i | -d] [-h] [-v <value>]  
options:
  -i	increase backlight
  -d	decrease backlight
  -v	gives the adjustment step a new value in percent (0-50)
  -h	show this message

example: bright -iv 20 - increase brightness by a value of 20 percent.
if -v is not passed, default increment is 5 percent.

Setup

I have used Autotools to create the make and configure files, and I have created a tarball for easy installing. First you need to create a file in the /etc/udev/rules.d/ catalog with a file called backlight.rules containing the following rules to grant access to the brightness-file for users in the video group:

SUBSYSTEM=="backlight", ACTION=="add", \
  RUN+="/bin/chgrp video /sys/class/backlight/intel_backlight/brightness", \
  RUN+="/bin/chmod g+w /sys/class/backlight/intel_backlight/brightness"
ACTION=="add", SUBSYSTEM=="backlight", KERNEL=="intel_backlight", GROUP="video", MODE="0664"

And do not forget to add the relevant users to the video group if they are not already members.

There are currently two ways of installing:

1. Downloading the tarball:

• Download the tarball to your computer
• Extract the contens in a suited place
• Run the following code inside the extracted folder to install:

  ./configure
  make
  sudo make install
  

2. Download the git-repository (excluding the tarball) and use autotools yourself:

• If you chose this option I assume you know what you are doing and do not need instructions.

License

This program is licensed under the GNU GPL v3, for more information see LICENSE. Copyright (C) 2021 Jonas Jørgensen

Since this primarily is a final project in a web course, I do not want contributions on the code for now. If you have any comments or suggestions feel free to email me on [email protected].