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brightnessctl

repository·master·Indexed 21 days ago

https://github.com/hummer12007/brightnessctl

A Linux utility for reading and controlling device brightness, including backlights and LEDs. It supports percentage-based adjustments, delta changes, and state saving/restoring. The tool provides a CLI for operations such as getting, setting, and listing device brightness, with support for udev rules, SUID binaries, or systemd-logind for permission management.

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What's inside brightnessctl

  1. Configure brightness for external monitors

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    By default, brightnessctl controls internal backlight and LEDs. To control the brightness of an external monitor, you must use the ddcci-driver-linux kernel module to expose those controls to the system. This module is available in the repositories for AUR, Debian, Nix, Ubuntu, and Void.

  2. Install brightnessctl

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    The brightnessctl program can be installed via package managers on various Linux distributions:

    • Alpine Linux: Available in edge.
    • Arch Linux: Available in extra/x86_64.
    • Void Linux: Available via void-packages.
    • Debian: Available starting with Buster (and derivatives).
    • Ubuntu: Available starting with 18.04 (and derivatives).
    • openSUSE: Available in Tumbleweed; use OBS utilities/brightnessctl for Leap < 15.1.
    • Fedora: Available in Fedora 31+.
    • NixOS/nix: Available starting with 17.09.

    Alternatively, you can build from source using:

    ./configure && make install

    Consult ./configure --help for build-time options.

  3. Use brightnessctl to control device brightness

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    The brightnessctl CLI follows this syntax: brightnessctl [options] [operation] [value]

    Operations

    • i, info: Get device information.
    • g, get: Get current brightness.
    • m, max: Get maximum brightness.
    • s, set VALUE: Set brightness to a specific value.

    Valid Values

    You can specify brightness using several formats:

    • Specific value: e.g., 500
    • Percentage value: e.g., 50%
    • Specific delta: e.g., 50- or +10
    • Percentage delta: e.g., 50%- or +10%

    Common Options

    • -l, --list: List devices with available brightness controls.
    • -d, --device=DEVICE: Specify a device name (supports wildcards).
    • -c, --class=CLASS: Specify a device class.
    • -s, --save: Save the current brightness state to a temporary file (useful for restoring later).
    • -r, --restore: Restore the previously saved state.
    • -q, --quiet: Suppress output.
    • -p, --pretend: Perform a dry run (do not write changes).

  4. Configure permissions for modifying brightness

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    Modifying brightness requires write permissions for device files or systemd support. brightnessctl supports three methods to achieve this without requiring sudo or su for every command:

    1. udev rules (Default): Installs rules that grant permissions to the video class for users in the video group, and the leds class for users in the input group. Ensure your user is a member of these groups.
    2. SUID binary: Installing brightnessctl as a suid binary.
    3. systemd-logind: Using the systemd-logind API.

  5. Reference: brightnessctl CLI options

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    Full list of command-line options for brightnessctl.

    Options:
  -l, --list           list devices with available brightness controls.
  -q, --quiet          suppress output.
  -p, --pretend        do not perform write operations.
  -m, --machine-readable produce machine-readable output.
  -n, --min-value      set minimum brightness, defaults to 1.
  -e, --exponent[=K]   changes percentage curve to exponential.
  -s, --save           save previous state in a temporary file.
  -r, --restore        restore previous saved state.
  -h, --help           print this help.
  -d, --device=DEVICE  specify device name (can be a wildcard).
  -c, --class=CLASS    specify device class.
  -V, --version        print version and exit.

  6. Reference: brightnessctl CLI operations

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    Full list of available operations for brightnessctl.

    Operations:
  i, info             get device info.
  g, get              get current brightness of the device.
  m, max              get maximum brightness of the device.
  s, set VALUE        set brightness of the device.