Ubuntu – Control monitor brightness with keyboard shortcut

brightnessdellgnomekeyboardshortcut-keys

I can control the brightness of my DELL S2216H connected with HDMI via the command:

ddccontrol -p -r 0x10 -w 53

where in this example the number 53 represents the brightness level (range 0 to 100). But I don't know how to link the command to my brightness keys on my keyboard or add laptop like slider next to volume control in Gnome-panel

while searching on the topic, i read this question
Control external monitor brightness via software
but the accepted answer to that question doesn't solve my issue

my output of ddccontrol -p is is posted here at pastebin

UPDATE
tried the first solution.

python3 /home/sumeet/set_brightness.py up

No monitor supporting DDC/CI available.
If your graphics card need it, please check all the required kernel modules are loaded (i2c-dev, and your framebuffer driver).
Traceback (most recent call last):
  File "/home/sumeet/set_brightness.py", line 22, in <module>
    currval = int(next(obj for obj in section if obj.startswith("value")).split("=")[-1].strip(","))
StopIteration

UPDATE 2

output of This Script from what I understand it's not even detecting my monitor. but first (original) command still works

python3 /home/sumeet/brightness.py
No monitor supporting DDC/CI available.
If your graphics card need it, please check all the required kernel modules are loaded (i2c-dev, and your framebuffer driver).
ddccontrol version 0.4.2
Copyright 2004-2005 Oleg I. Vdovikin (oleg@cs.msu.su)
Copyright 2004-2006 Nicolas Boichat (nicolas@boichat.ch)
This program comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of this program under the terms of the GNU General Public License.

Probing for available monitors.......
Detected monitors :

UPDATE 3
even the first command isn't working now, how can i get that working?

Best Answer

Bind a keyboard shortcut

Gnome allows you to bind any key to run a command of your choice. If xbacklight worked, I'd suggest you use that. Since you said it does not, you can use the brightness script I'll include below.

Go to Settings → Keyboard → Shortcuts and scroll to the bottom of the list.
You'll find a + button. Click it to open the Add Custom Shortcut dialog:
1. For the Name put "Brightness Up", for the Command, type brightness +10
2. Click the "Set Shortcut" button and hit the key you want to turn the screen brighter.
Now do the same for "Brightness Down", using brightness -10.

b9's brightness script

Many external monitors cannot control the backlight lamp with xbacklight. But you can still control the brightness using software. Here's a script I wrote which does that.

#!/bin/bash
# brightness: Change all monitors brightness in software.
# by hackerb9, 2019

# Examples:  brightness 75;  brightness -5; brightness +10
# Usage:
#       brightess [n] [+n] [-n]
#       n       An integer from 0 to 100 specifies a brightness level.
#       +n      Increase brightness by n.
#       -n      Decrease brightness by n.
#               No argument shows current brightness level.

b=$(xrandr --current --verbose | grep Brightness)
b=${b#*: }                      # Remove "Brightness: "
b=${b#0.}                       # 0.30 --> 30
[[ $b == "1.0" ]] && b="100"
case $1 in
    +*|-*)
        b=$((b $1))             # b=b+10,  b=b-10
        ;;
    [0-9]*)
        b=$1                    # b=75
        ;;
    *)
        echo $b; exit
        ;;
esac

[[ $b -lt 0 ]] && b=0
[[ $b -gt 100 ]] && b=100

if [[ $b -eq 100 ]]; then
    b=1.0
else
    b=0.$b
fi

outputs=$(xrandr --current | awk '$2 == "connected" {print $1}')
for o in $outputs; do
    xrandr --output $o --brightness $b
done

To install the script, paste it into a file called brightness, set it executable, and put it in your path. Or, you can cut-and-paste these commands:

wget https://github.com/hackerb9/brightness/raw/master/brightness
chmod 755 brightness
sudo mv brightness /usr/local/bin/

xbacklight

If xbacklight did work for you, you could use it as a drop-in replacement for brightness in the above instructions. (xbacklight +10 for Brightness Up, xbacklight -10 for Down.)

Related Solutions

Ubuntu – Control external monitor brightness via software

I don't think your desired solution of getting your external monitor in /sys/class/backlight will work, but the good news is that you can have the nice brightness animation!

Try

notify-send " " -i notification-display-brightness-low -h int:value:50 -h string:x-canonical-private-synchronous:brightness &

Now we can make a script that simulates Ubuntu's brightness changer:

#!/bin/bash
#get current brightness
presbright=$(ddccontrol -p | grep -A1 0x10 | tr -d '\n\t' | sed 's/.*value=\([^a-zA-Z]*\),.*/\1/')
#stepsize for the brightness change
stepsize=10

case "$1" in
        up)
          newbright=$(( ${presbright}+${stepsize} ))
          newbright=$(echo $newbright | awk '{if($1 < 100){if($1 > 0) print $1; else print 0;} else print 100;}')

          notify-send " " -i notification-display-brightness-low -h int:value:$newbright -h string:x-canonical-private-synchronous:brightness &
          ddccontrol -p -r 0x10 -w $newbright
        ;;
        down)
          newbright=$(( ${presbright}-${stepsize} ))
          newbright=$(echo $newbright | awk '{if($1 < 100){if($1 > 0) print $1; else print 0;} else print 100;}')

          notify-send " " -i notification-display-brightness-low -h int:value:$newbright -h string:x-canonical-private-synchronous:brightness &
          ddccontrol -p -r 0x10 -w $newbright            
        ;;
        status)
          echo $presbright
        ;;
        *)
          echo "Accepted arguments are: up, down, status."
        ;;
esac

exit 0

As you can see it clamps the values between 0 and 100. Now you can bind the up and down calls to the script to some keyboard shortcuts of your choice with System Settings > Keyboard > Shortcuts, like fotomonster suggested.

Notes:
I don't know how much time ddccontrol -p takes, if it is too long you can also add a sync option to the script which saves the brightness value of the monitor to a file. Then instead of getting the current brightness from ddccontrol you can simply get it from your file, which should be much faster. Of course you would need to update the up and down calls to write the new brightness to the file...

script inspired by this post on archlinux.

Ubuntu – Typing “↑” (upwards arrow) with a keyboard shortcut

If you look at the file /usr/share/X11/xkb/symbols/latin, you will find the following lines:

key <AD06>  { [         y,          Y,    leftarrow,          yen ] };
key <AD07>  { [         u,          U,    downarrow,      uparrow ] };
key <AD08>  { [         i,          I,   rightarrow,     idotless ] };
key <AD06>  { [         z,          Z,    leftarrow,          yen ] };

So apparently an up arrow (↑) is already defined -- for ALT GR+SHIFT+U. If not, you can copy the file to a directory, edit it at will, name the profile somehow (say "foo" instead of "latin") and simply run

setxkbmap -I. -layout foo

(the -I. makes setxkbmap look for layout files also in the current directory).

The four strings assign to each key give the four characters that are produced by pressing the key, key with shift, key with altgr and key with algr+shift. The names of the entities (keysyms) that xkb can recognize can be found here.