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[Bug 1270579] Re: Ubuntu should have an upstart job for saving/restoring backlight level on laptops

 

Cody, the current version of my script works only with one graphical adapter (its brightness file is named /sys/class/backlight/acpi_video0/brightness).
You can customize this value in my script at row 16
     BRIGHTNESS_CONTROL=/sys/class/backlight/acpi_video0/brightness 
to path which is *correct* for your hardware.

Correct path may be determined by the following steps:
1. List all paths with brightness file in /sys/class/backlight dir with the command
     ls /sys/class/backlight/*/brightness

example: 
     /sys/class/backlight/acpi_video0/brightness
     /sys/class/backlight/acpi_video1/brightness

2a. Read values of brightness from files with the command:
     cat /sys/class/backlight/*/brightness

example:
     3
     8

2b. Change backlight level with hardware keys (Fn+...) and read again:
     cat /sys/class/backlight/*/brightness

example:
     4
     8
2c. The *correct* path to brightness control file corresponds to the changed value.

example: 
     /sys/class/backlight/acpi_video0/brightness # first value changed, so first file
3. Try to write brightness level manually to *correct* brightness file:
     sudo su
     echo 3 > /sys/class/backlight/acpi_video0/brightness # example on my hardware
4. Change BRIGHTNESS_CONTROL variable to the *correct* path in /etc/init.d/brightness with the command
     sudo gedit /etc/init.d/brightness

I'll update my script soon to do all steps automatically.

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https://bugs.launchpad.net/bugs/1270579

Title:
  Ubuntu should have an upstart job for saving/restoring backlight level
  on laptops

Status in elementary OS:
  New
Status in One Hundred Papercuts:
  Confirmed
Status in Ubuntu MATE:
  Opinion
Status in systemd package in Ubuntu:
  Triaged
Status in sysvinit package in Ubuntu:
  Invalid
Status in sysvinit package in Debian:
  New

Bug description:
  I have tested many distros - Arch, OpenSuSe 13.1, Fedora 20, ALT Linux p7, Sabayon, Mageia 4.
  Many of them are based on systemd.
  It does not matter what init system they use, but all of them have very usefull script (or binary program, I don't know) for saving and restoring backlight level on laptop.

  In these distros there is a script for save and restore backlight levels for two video-cards (acpi_video0 and acpi_video1). During system boot it is indicated as follows:
  "
  [  OK  ] Started Load/Save Screen Backlight Brightness of acpi_video1.
  [  OK  ] Started Load/Save Screen Backlight Brightness of acpi_video0.
  ".

  I have a draft version, which works normally on my VAIO F13Z1R laptop with Ubuntu 12.04.4. It is in attachment.
  You can use it unmodified or modify it for compatibility or something. I made symlinks for it:
  ln -s /etc/init.d/brightness /etc/rc0.d/S25backlight
  ln -s /etc/init.d/brightness /etc/rcS.d/S25backlight
  ln -s /etc/init.d/brightness /etc/rc6.d/S25backlight

  For details you can read my comment on askubuntu
  (http://askubuntu.com/a/227553/66509).

  I think that having a script for saving and restoring backlight level is very useful for laptop Ubuntu users.
  So, please, add such init script to default Ubuntu installation.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: initscripts 2.88dsf-41ubuntu5
  ProcVersionSignature: Ubuntu 3.13.0-4.19-generic 3.13.0-rc8
  Uname: Linux 3.13.0-4-generic i686
  ApportVersion: 2.13.1-0ubuntu1
  Architecture: i386
  CurrentDesktop: GNOME
  Date: Sun Jan 19 17:20:26 2014
  InstallationDate: Installed on 2013-10-20 (91 days ago)
  InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release i386 (20131016.1)
  SourcePackage: sysvinit
  UpgradeStatus: Upgraded to trusty on 2013-11-19 (61 days ago)

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