16.04 Brightness Battery – Update Brightness Level Depending on Power Source

16.04bashbatterybrightnessscripts

I recently migrated to 64 Bit 16.04 LTS from 32 Bit 14.04 LTS on my Toshiba L645 laptop. In 14.04 LTS system, I had a script that automatically updated the brightness level depending on the power source. Unfortunately I didn't save that script before overwriting the system. Currently, I am using the following script

#!/usr/bin/env bash
#
###########################################################
# Author: Serg Kolo , contact: 1047481448@qq.com 
# Date: February 26 2016 
# Purpose: Brightness control that polls for
#          ac adapter presence. Uses
# Dependencies: on_ac_power script, dbus, Unity/Gnome 
# Written for: http://askubuntu.com/q/739617/295286
# Tested on: Ubuntu 14.04 LTS
###########################################################
# Copyright: Serg Kolo , 2016
#    
#     Permission to use, copy, modify, and distribute this software is hereby granted
#     without fee, provided that  the copyright notice above and this permission statement
#     appear in all copies.
#
#     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
#     THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#     DEALINGS IN THE SOFTWARE.

# uncomment the line bellow for debugging
#set -x

ARGV0="$0"
ARGC=$#


main()
{

  # defaults
  local DISPLAY=:0
  local DECREASE=30
  local INCREASE=75
  local RCFILE="$HOME/.auto-backlightrc"
  #---

  # Check the settings
  if [ -f $RCFILE ]
  then 
       source $RCFILE 
  else
       create_rcfile $DECREASE $INCREASE
  fi
  #---

  # now actually test if we're using ac adapter
  if ! on_ac_power 
  then 
        change_brightness $DECREASE
  # The two lines bellow are optional for 
  # setting brightness if on AC. remove # 
  # if you want to use these two

  # else 
       # change_brightness $INCREASE
  fi

}

change_brightness()
{
  dbus-send --session --print-reply\
    --dest=org.gnome.SettingsDaemon.Power\
    /org/gnome/SettingsDaemon/Power \
    org.gnome.SettingsDaemon.Power.Screen.SetPercentage uint32:"$1"
}

create_rcfile()
{
  echo "DECREASE="$1 >  "$RCFILE"
  echo "INCREASE="$2 >> "$RCFILE"
}


while true
do
   main
   sleep 0.25
done

However, this script only works when power is switched from AC to Battery and does not restore the brightness level once the AC is back on. Also, once on Battery, this script consistently tries to set the brightness at the predefined level and even if I try to change that manually it resets that. I would like to be able to change the brightness level manually if I desire even in battery mode.

Best Answer

Intro

The script below allows remembering brightness levels depending on the power source used by a laptop. It defaults to 50% on battery, 90% on AC.

Overview of options and usage

source_monitor.sh [-a INT] [-b INT] [-v] [-h]

-a set initial brightness on AC adapter
-b set initial brightness on batter
-v enable verbose output
-h prints this help text

Installation

Installation using git through terminal:

Run sudo apt-get install git to install git
Run mkdir $HOME/bin. Skip this step if $HOME/bin exists already
cd $HOME/bin
Run git clone https://github.com/SergKolo/sergrep.git
The script will be in $HOME/bin/sergrep/source_monitor.sh. Make sure the script is executable with chmod +x $HOME/bin/sergrep/source_monitor.sh
Add the script as a startup application. Look for Startup Applications menu in Unity Dash or Gnome search. Alternatively, run gnome-session-properties command in terminal to launch the menu. Add the full path to script as startup application so that it launches every time you log into GUI.

Alternatively, you can copy and save script source by oneself, chmod +x file, and go through the step #6 described above.

To make the script automatically start every time you log in to Gnome or Unity, use Startup Applications utility.

Script source

#!/usr/bin/env bash
#
###########################################################
# Author: Serg Kolo , contact: 1047481448@qq.com 
# Date: June 18th 2016
# Purpose: Script that remembers and sets brightness
#      depending on power sources
# 
# Written for: https://askubuntu.com/q/788383/295286
# Tested on: Ubuntu 16.04 LTS , Ubuntu Kylin 16.04 LTS
###########################################################
# Copyright: Serg Kolo , 2016
#    
#     Permission to use, copy, modify, and distribute this software is hereby granted
#     without fee, provided that  the copyright notice above and this permission statement
#     appear in all copies.
#
#     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
#     THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#     DEALINGS IN THE SOFTWARE.

ARGV0="$0"
ARGC=$#
wait_ac_connect()
{
  while ! on_ac_power ; do : ; sleep 0.25 ; done
  $VERBOSE && echo "<<< adapter plugged in"
}

wait_ac_disconnect()
{
  while on_ac_power ; do : ; sleep 1.25 ; done 
  $VERBOSE && echo "<<< adapter unplugged"
}

change_brightness()
{
  qdbus org.gnome.SettingsDaemon \
       /org/gnome/SettingsDaemon/Power \
      org.gnome.SettingsDaemon.Power.Screen.SetPercentage "$1"
}

get_brightness()
{
  qdbus org.gnome.SettingsDaemon \
        /org/gnome/SettingsDaemon/Power \
        org.gnome.SettingsDaemon.Power.Screen.GetPercentage
}

print_usage()
{
cat <<EOF

source_monitor.sh [-a INT] [-b INT] [-v] [-h]

-a set initial brightness on AC adapter
-b set initial brightness on batter
-v enable verbose output
-h prints this help text

Copyright Serg Kolo , 2016
EOF
}

parse_args()
{
 # boiler-pate code for reusing, options may change
 local OPTIND opt  # OPTIND must be there, 
                   # opt can be renamed to anything
 # no leading : means errors reported(which is what i want)
 # : after letter means options takes args, no :  - no args
 while getopts "a:b:vh" opt
 do
   case ${opt} in
      a)  AC_PERCENTAGE="${OPTARG}"
        ;;
      b) BAT_PERCENTAGE="${OPTARG}"
        ;;
      v) VERBOSE=true
        ;;
      h) print_usage && exit 0
        ;;
     \?)
      echo "Invalid option: -$OPTARG" >&2
      ;;
    esac
  done
  shift $((OPTIND-1))
}

main()
{

    # default values, if -a,-b, or -v options given
    # they will be changed
    local BAT_PERCENTAGE=50
    local AC_PERCENTAGE=90
    local VERBOSE=false # for debugging

    parse_args "$@"

    while true
    do

      if on_ac_power ; then
         wait_ac_disconnect
          AC_PERCENTAGE=$(($(get_brightness)+1)) # too long to explain why +1
                         # just try it for yourself
          sleep 0.25
          change_brightness "$BAT_PERCENTAGE" > /dev/null
      else
          wait_ac_connect
          BAT_PERCENTAGE=$(($(get_brightness)+1))
          sleep 0.25
          change_brightness "$AC_PERCENTAGE" > /dev/null
      fi

      sleep 0.25

    done

}

main "$@"

Related Solutions

Ubuntu – Is there an App that can make the desktop dimmer

Follow these steps exactly:

Open terminal via Ctrl-Alt-T
Create a folder for the script
```
mkdir -p ~/bin
```
Open the file ~/bin/setup.sh in gedit.
```
gedit ~/bin/setup.sh 
```

Copy over the code below save the file, close the editor.

#!/bin/sh
# Author: Serg Kolo
# Date: Mon Aug 24 , 2015
# Description: setup script for creating
# launcher and setting up the Dimmer script

DESKFILE="$HOME/bin/Dimmer.desktop"
SCHEMA="com.canonical.Unity.Launcher"
KEY="favorites"
SCRIPTFILE="$HOME/bin/Dimmer.sh"

createBinFolder() {
 if [ ! -e "$HOME/bin" ]; then
   mkdir "$HOME/bin"
 fi
 echo "created bin folder"
}

createLauncher() {
 OUTPUT="$(gsettings get $SCHEMA $KEY | awk -v file="$DESKFILE" -v sq="'"  '{ sub(/\]/,""); print  $0","sq"application://"file sq "]"  }')" ;
 gsettings set $SCHEMA $KEY "$OUTPUT" ;
 echo "Launcher for Dimmer created"
}

createScriptFile() {
 touch "$SCRIPTFILE"
 chmod 755 "$SCRIPTFILE"
 echo "Created script file. Please copy over the code to \"$SCRIPTFILE\""
}

createDeskFile() {
 printf "[Desktop Entry]\nName=Dimmer\nExec=%s\nType=Application\nTerminal=false" "$SCRIPTFILE" > "$DESKFILE"
}

createBinFolder
createScriptFile
createDeskFile
createLauncher

Make the file executable and start the setup script
```
chmod 755 ~/bin/setup.sh && ~/bin/setup.sh
```
That script will create bin folder and blank Dimmer.sh file.
Edit the file Dimmer.sh
```
gedit ~/bin/Dimmer.sh
```

Copy the code below, save and close the editor

#!/bin/sh
# Name: backlightscript
# Author: Serg Kolo
# Date: March 2 , 2015
# Description: Simple script to change screen brightness using xrandr

# uncomment this for debugging as needed
# set -x

NEWVAL=$( zenity --scale --min-value=0 --max-value=7 --text="Enter number between 0 and 7" ) && brightness=$(($NEWVAL+2))

if [ "$NEWVAL" != "" ]; then
    xrandr --output "$( xrandr | awk '$2=="connected" {print $1}')" --brightness 0.$brightness
fi

Now you should be able to double click on the launcher and get that dimmer app working.

Make Ubuntu Remember Screen Brightness Level Without xbacklight

Actually, I would like to make my Ubuntu remember the level of brightness that was used last. How exactly can I do that? Here's some information:

Introduction

The script below addresses OP's need to store and restore screen brightness that was used last. It works in conjunction with the lightdm greeter and is activated by lightdm. There's no requirement to use lightdm, so if you prefer to use a cron job, you can do so.

Basic idea:

Have the script stored somewhere (either by getting it here or through github)
Create /etc/lightdm/lightdm.conf using the sudo privilege.
Make sure that file has 3 lines: [SeatDefaults] , display-setup-script, and display-stopped script. Look below for details. Script header also gives overview.

Script Source

#!/usr/bin/env bash
#
###########################################################
# Author: Serg Kolo , contact: 1047481448@qq.com 
# Date: March 7th, 2016
# Purpose: Script that will remember screen brightness
#          Must be used in conjunction with lightdm
#          Place the following 5 lines into /etc/lightdm/lightdm.conf
#
#           [SeatDefaults]
#           #display-setup-script = Script to run when starting a greeter session (runs as root)
#           display-setup-script = /home/USER/bin/sergrep/brightness.sh restore
#           #display-stopped-script = Script to run after stopping the display server (runs as root)
#           display-stopped-script = /home/USER/bin/sergrep/brightness.sh store
#
#           Basic idea is that you must give full path and either store or restore as an option 
# Written for: http://askubuntu.com/q/739654/295286
# Tested on:  Ubuntu 14.04 LTS
# Version: 1.2 , added brightness limit, file creation
###########################################################
# Copyright: Serg Kolo , 2016
#    
#     Permission to use, copy, modify, and distribute this software is hereby granted
#     without fee, provided that  the copyright notice above and this permission statement
#     appear in all copies.
#
#     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
#     THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#     DEALINGS IN THE SOFTWARE.
ARGV0=$0
ARGC=$#



store()
{
   cat "$SYSDIR"/*/actual_brightness > "$1"
}
#----------

# This function restores brightness. We avoid 
# setting brightness to complete 0, hence
# minimum is 10% that can be restored.

restore()
{
  MAX=$(cat "$SYSDIR"/*/max_brightness  )
  LIMIT=$((MAX/10)) # get approx 10 percent value
  VAL=$(cat "$1" )
  if [ "$VAL" -lt "$LIMIT"  ] ;
  then
       # avoid going bellow 10% of brightness
       # we don't want user's screen to be completely dark
       echo "$LIMIT" > "$SYSDIR"/*/brightness
  else
       echo "$VAL" > "$SYSDIR"/*/brightness
  fi
}
#------------

# This function works for initial run of the script; the script cannot set
# brightness unless datafile exists first, so here we create the file
# Initial value there will be whatever the current brightness on first
# reboot was

create_datafile()
{
  cat "$SYSDIR"/*/actual_brightness > "$1" 
}

puke(){
    printf "%s\n" "$@" > /dev/stderr
    exit 1
}

main()
{
  local DATAFILE="/opt/.last_brightness"
  local SYSDIR="/sys/class/backlight" # sysfs location of all the data

  # Check pre-conditions for running the script
  if [ "$ARGC" -ne 1  ];then
     puke "Script requires 1 argument"
  fi

  if [ $(id -u) -ne 0 ]   ; then
     puke "Script has to run as root"
  fi

  # ensure datafile exists
  [ -f "$DATAFILE"  ] || create_datafile "$DATAFILE"

  # perform storing or restoring function
  case "$1" in
     'restore') restore  $DATAFILE ;;
     'store') store $DATAFILE ;;
     *) puke "Unknown argument";;
  esac

}

main "$@"

Getting and Setting up the Script

You can either copy the script directly or follow these steps from the command line ( to open command line , press CtrlAltT )

sudo apt-get install git
cd /opt
sudo git clone https://github.com/SergKolo/sergrep.git

The script will be located in /opt/sergrep/brightness.sh, so we do a:

sudo chmod +x /opt/sergrep/brightness.sh

to make it executable. Next, we need to set it up to work with lightdm. Create the /etc/lightdm/lightdm.conf file , either by opening it with command line nano text editor (the command is sudo nano /etc/lightdm/lightdm.conf ) or graphical gedit ( pkexec gedit /etc/lightdm/lightdm.conf )

Write to that file the following lines:

[SeatDefaults]
#display-setup-script = Script to run when starting a greeter session (runs as root)
display-setup-script = /opt/sergrep/brightness.sh restore
#display-stopped-script = Script to run after stopping the display server (runs as root)
display-stopped-script = /opt/sergrep/brightness.sh store

Save and exit

Indepth Overview

You've already discovered that you can write to /sys/class/backlight/*/brightness file directly , and you can also read in those values as well. Problem is that /sys is a virtual filesystem, so once you reboot, all the files in that filesystem disappear.

So you could store value in /sys/class/backlight/*/actual_brightness into a permanent file on every reboot. The question is how - via cron job, via lightdm, or via other means. Personally, I chose the lightdm route.

Basically we take advantage of lightdm's feature - being able to run a script before the greeter starts and after the session exits. The brightness is recorded to /opt/.last_brightness file and read from each time the script starts. We're essentially performing two actions with the same script, just by passing different arguments.

Best Answer

Related Solutions

Ubuntu – Is there an App that can make the desktop dimmer

Make Ubuntu Remember Screen Brightness Level Without xbacklight

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