バックライト制御コマンドのybacklight

$ xbacklight -get
No outputs have backlight property
$ xbacklight = 100
No outputs have backlight property
$ xbacklight + 10
No outputs have backlight property
$ xbacklight - 10
No outputs have backlight property

$ sudo sh -c "echo 1000 > /sys/class/backlight/intel_backlight/brightness"

$ ybacklight -h
Usage: /home/mk/bin/ybacklight [options]
  Options:
  -d <driver> or -driver <driver>: Use driver <driver> (NB: -display is
                                   also supported for compatibility)
  -help: Print this help
  -set <percentage> or = <percentage>: Set backlight to <percentage>
  -inc <percentage> or + <percentage>: Increase backlight by <percentage>
  -dec <percentage> or - <percentage>: Decrease backlight by <percentage>
  -get: Get backlight percentage
  -time <ignored> or -steps <ignored>: Unsupported, ignored
  -v: Verbose output

$ ybacklight -get
30
$ ybacklight +10
Permissions conflict.  Can't write to: ( /sys/class/backlight/intel_backlight/brightness )

$ ls -l /sys/class/backlight/intel_backlight/brightness
-rw-r--r-- 1 root root 4096  4月  5 06:48 /sys/class/backlight/intel_backlight/brightness
$ sudo chmod o+w /sys/class/backlight/intel_backlight/brightness
$ ls -l /sys/class/backlight/intel_backlight/brightness
-rw-r--rw- 1 root root 4096  4月  5 06:48 /sys/class/backlight/intel_backlight/brightness
$ ybacklight +10
40
$ ybacklight -10
30