Cameron Nemo OCTOBER 2018
brillo - control the brightness of backlight and keyboard LED devices
brillo [operation [value]] [-k] [-q|-r] [-m|-c] [-e|-s ctrl] [-u usecs] [-v loglevel]
brillo is a tool for controlling the brightness of backlight and LED devices on Linux. Notable features include:
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Automatic best controller detection | ||
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Smooth transitions and exponential (natural) adjustments | ||
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Ability to save and restore brightness across boots | ||
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Directly using sysfs to set brightness without relying on X | ||
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Unprivileged access with no new setuid binaries | ||
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Containment with AppArmor |
Operations
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-G: Get brightness value (default) |
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-S VALUE: Set brightness to value |
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-A VALUE: Increment brightness by given value |
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-U VALUE: Decrement brightness by given value |
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-O: Store the current brightness |
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-I: Restore cached brightness |
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-L: List available devices |
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-H: Show a short help output |
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-V: Report the version |
Controllers
The default controller is automatically selected to maximize precision. To select every controller available, use the -e option. To select a specific controller, use the -s option.
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-a: Automatic controller selection (default) |
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-e: Operate on every controller available |
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-s CONTROLLER: Manual controller selection |
The list operation (-L) can be used to discover available controllers.
Targets
By default, brillo acts on the display devices, but the -k option can be used to adjust keyboard backlights instead. In either case, it may be necessary to specify an alternative controller.
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-l: Act on display backlight (default) |
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-k: Act on keyboard backlight and LEDs |
Fields
By default, brillo acts on the brightness property. With these options, the maximum brightness of a controller can be retrieved. In addition, it is possible to set (or retrieve) a minimum cap, which is used to prevent lowering the brightness beyond a certain threshold. This is especially useful for devices that become pitch black when the brightness is set to 0.
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-b: Current brightness (default) |
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-m: Maximum brightness |
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-c: Minimum brightness |
Value modes
Values may be given, or presented, in percent or raw mode.
The default value mode is linear percentages, however the -q option can be used for exponential percentages. Exponential mode offers a more natural and gradual brightness scale.
Raw mode will use the same format and range given by the device driver; this mode is most useful when a high degree of precision is required, such as for keyboard controllers.
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-p: Linear percentages (default) |
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-q: Exponential percentages |
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-r: Raw values |
Smooth adjustment
brillo is capable of gradually adjusting the brightness over a specified time period. Use the -u microseconds option to specify how long the operation should take. This flag is silently ignored when not setting the brightness.
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-u microseconds: time used to space the operation out |
Verbosity
By default, brillo outputs only warnings or more severe messages. To enable more verbose logs on stderr, use the verbosity argument: -v loglevel. The loglevel is a value between 0 and 8 (corresponding to syslog severities).
Get the current brightness in percent:
brillo [-G]
Increase brightness by 5 percent:
brillo -A 5
Specify the controller to use:
brillo -s intel_backlight -A 5
Set the brightness to 50% for every controller:
brillo -e -S 50
Retrieve or increase the brightness using an exponential scale:
brillo -q
brillo -q -A 5
Decrease the brightness and smooth the operation over 1500 microseconds:
brillo -u 150000 -U 5
Get the raw maximum brightness value:
brillo -rm
Set the minimum cap for the acpi_video0 controller to a raw value of 2:
brillo -rc -s acpi_video0 -S 2
Note: subsequent attempts to set the controller’s brightness to a raw value less than 2 will then be raised to this minimum threshold.
List keyboard controllers:
brillo -Lk
Activate a specific controller LED:
brillo -k -s "input15::scrolllock" -S 100
Note: LEDs often only take 0 or 1 in raw value (i.e. for off/on). In these cases, you can use any non-zero value instead of 100.
Copyright (C) 2018-2019 Cameron Nemo, 2014 Fredrik Haikarainen
This is free software, see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE