brightnessctl讀取和控制設備亮度的程序

Usage: brightnessctl [options] [operation] [value]

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.

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.

Valid values:
  specific value		Example: 500
  percentage value		Example: 50%
  specific delta		Example: 50- or +10
  percentage delta		Example: 50%- or +10%