lightctl

lightctl

A Linux backlight / LEDs controller similar to brightnessctl, written in Go and featuring smooth brightness changes.

Install

Requirements

• Go

Procedure

go install github.com/denysvitali/lightctl@latest

Usage

Usage: lightctl [--device DEVICE] [--debug] <command> [<args>]

Options:
  --device DEVICE, -d DEVICE
  --debug, -D
  --help, -h             display this help and exit

Commands:
  increase
  decrease
  set
  list

List

This command returns a list of controllable outputs (backlights / LEDs). By specifying -d DEVICE_NAME to the other commands, one can perform an action on a specific device.

$ lightctl list
intel_backlight
input3::capslock
input3::numlock
input3::scrolllock
phy0-led
platform::micmute
platform::mute
tpacpi::kbd_backlight
tpacpi::power
tpacpi::standby
tpacpi::thinklight
tpacpi::thinkvantage

Increase

Increases the brightness of the specified -d DEVICE by the specified value / percentage.

Usage: lightctl increase [--smooth-ms SMOOTH-MS] TO

Positional arguments:
  TO

Options:
  --smooth-ms SMOOTH-MS, -s SMOOTH-MS [default: 0]

Global options:
  --device DEVICE, -d DEVICE
  --debug, -D
  --help, -h             display this help and exit

Example:

lightctl increase -s 100 10%

This command smoothly increases (in 100 ms) the default device's brightness by 10%. As an example, if the previous brightness percentage was 15%, this command will increase the brightness to 25% by linearly increasing it and completing the action in 100ms.

Decrease

Same as increase, but reduces the brightness

$ lightctl decrease -h
Usage: lightctl decrease [--smooth-ms SMOOTH-MS] TO

Positional arguments:
  TO

Options:
  --smooth-ms SMOOTH-MS, -s SMOOTH-MS [default: 0]

Global options:
  --device DEVICE, -d DEVICE
  --debug, -D
  --help, -h             display this help and exit

Set

Sets the brightness to the specified value / percentage

$ lightctl set -h
Usage: lightctl set [--smooth-ms SMOOTH-MS] TO

Positional arguments:
  TO

Options:
  --smooth-ms SMOOTH-MS, -s SMOOTH-MS [default: 0]

Global options:
  --device DEVICE, -d DEVICE
  --debug, -D
  --help, -h             display this help and exit

Example:

$ lightctl set -s 200 50%

Sets the brightness to 50% linearly in 200ms.

Implementation

Under the hood lightctl uses two methods to change the brightness, depending on which permission the user running the software has.

1. Direct write to /sys/class/CLASS/DEVICE/brightness
2. DBUS org.freedesktop.login1 SetBrightness() method

The advantage of using the DBUS method is that the user doesn't need any particular privilege to run the command since this is handled by DBUS.

Compiling

go install ./

Running

lightctl -h