backlight_control

Increase/decrease the backlight by a specific percent count

$ backlight_control [+|-][5]

$ backlight_control [90]

$ backlight_control

backlight_control [OPTION]... [VALUE]

-s, --set VALUE
    Sets the display brightness to a specified VALUE. The VALUE typically represents a percentage (e.g., 50 for 50%) or an absolute brightness level, depending on implementation.

-g, --get
    Retrieves and displays the current brightness level of the display.

-u, --up [INCREMENT]
    Increases the display brightness. An optional INCREMENT value (e.g., 5 or 10) specifies by how much to increase it; if omitted, a default increment is often used.

-d, --down [DECREMENT]
    Decreases the display brightness. An optional DECREMENT value specifies by how much to decrease it; if omitted, a default decrement is often used.

--max
    Sets the display brightness to its maximum possible level.

--min
    Sets the display brightness to its minimum possible level.

-h, --help
    Displays a help message with usage information and available options.

The command backlight_control is not a standard Linux command. It is typically a custom user-defined script, an alias, or a function provided by a specific distribution, desktop environment, or personal configuration to simplify the process of adjusting screen brightness.

Its primary purpose would be to act as a convenient wrapper around lower-level backlight control mechanisms available in Linux. These underlying mechanisms commonly include:
- The /sys/class/backlight/ kernel interface, which exposes brightness control directly to userspace.
- Utilities like xbacklight or brightnessctl, which are more common command-line tools for backlight management.
- The xrandr utility for Xorg, which can control brightness on certain display outputs.

The specific functionality and options of backlight_control would entirely depend on how it is implemented on a given system.

As backlight_control is not a standard Linux command, its presence and functionality depend entirely on custom scripting or specific system configurations.

Users should be aware of the following:
- Non-Standard: It is not universally available across all Linux distributions or setups.
- Implementation Dependent: Its behavior, options, and underlying method of brightness control (e.g., /sys/class/backlight, xrandr, brightnessctl) are determined by its creator.
- Permissions: Controlling backlight often requires appropriate permissions, typically involving root access or membership in specific groups (e.g., video, input) to interact with kernel interfaces.
- Hardware and Driver Specifics: Backlight control can vary significantly between different hardware (e.g., Intel, AMD, NVIDIA GPUs) and their respective drivers.

The primary and most robust method for controlling display backlight on Linux at a low level is through the /sys/class/backlight/ pseudo-filesystem. This interface is exposed by the kernel and provides a standardized way to interact with backlight devices.

Inside this directory, you'll typically find subdirectories corresponding to detected backlight devices (e.g., intel_backlight, acpi_video0, amdgpu_bl0). Within each device directory, important files include:
- brightness: A file whose integer value represents the current brightness level.
- max_brightness: An integer value indicating the maximum possible brightness level for the device.
- actual_brightness: The actual current brightness as reported by the hardware.

To change brightness, a user (with appropriate permissions) would write a new integer value to the brightness file, typically after scaling it based on max_brightness.

There is no official history for a generic backlight_control command, as it is not a part of standard Linux utilities. Such commands typically emerge from individual users or community projects aiming to provide a simpler, more intuitive interface for a common system task (like brightness control) that otherwise might require more complex or less user-friendly commands (e.g., writing directly to /sys/class/backlight files). These scripts often become part of personal dotfiles, smaller utility packages, or distribution-specific enhancements.

brightnessctl(1), xbacklight(1), xrandr(1), acpi(4)