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[My name <plmalternate@xxxxxxxxx>]

Everything I wrote above is still true for me in 14.04, Trusty, 64 bit
version,  with pretty much the same setup, plain Openbox (no LXDE, no
Lubuntu, no other DE) and lxterminal.

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https://bugs.launchpad.net/bugs/1054298

Title:
  xbacklight doesn't work, but xrandr does and so does
  /sys/class/backlight

Status in “linux” package in Ubuntu:
  Expired

Bug description:
  Sony Vaio P
  Ubuntu Precise and Quantal
  kernel 3.5.0
  gma500_gfx kernel driver
  modesetting xorg driver
  Assume the current quantal & quantal-proposed versions of everything.

  xbacklight doesn't work. No backlight change, and no output from the program.
  "xbacklight" and "xbacklight -get" show nothing, no output from the program at all.
  "xbacklight -set50" and "xbacklight-d :0 -set 50" does nothing nor prints any output.

  However both sysfs and xrandr work fine.

  Specifically:
  xrandr --verbose lists outputs and shows the main screen has backlight property,
  and "xrandr --output LVDS-0 --set backlight 50" changes the backlight brightness.

  And

  "cat /sys/class/backlight/psb-bl/actual_brightness" shows the current brightness, and
  "echo 50 >/sys/class/backlight/psb-bl/brightness" changes the brightness.

  I have written the following script to use in place of xbacklight:
  http://forums.bodhilinux.com/index.php?/topic/5985-brightness-scripts/page__view__findpost__p__56911

  This script, both the sysfs and xrandr methods of it, works fine for me on the same machine.
  (for sysfs, I had to make a udev rule to allow users to write to the sysfs files, as noted on that page and in the --help output of the script)
  It requires zenity for the user interactive options. Not needed for the non-interactive options.

  -- 
  bkw

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