How to change the Monitor brightness on Linux?

Question

How do I programmatically change the monitor brightness on Linux?

I'm using SLES 11.

Quesnay

possible duplicate of Possible to change screen brightness with c? – Quesnay

Answer 1

You can always use

xrandr --output LVDS1 --brightness 0.9

Eosinophil

"LVDS1" is the name of the display you want to change. Run xrandr and check the name of the display you have. The line will look something like "LVDS1 connected 1920x1080+0+0". – Preestablish

Quote from man xrandr regarding --brightness: "this is a software only modification, if your hardware has support to actually change the brightness, you will probably prefer to use xbacklight" – Zincography

change LVDS1 to eDP if you have a laptop, if you have a DP monitor and have it connected with DP, use DP instad, same with DVI1,DVI2 etc – Watercolor

Amr is right. This can turn all white to black, or all black to white; but not make the white brigher – Hammy

As this answer do not really changes the brightness of the monitor you better try the possibilities from this answer: askubuntu.com/a/1181157/1046889 – Whirligig

Answer 2

You can try using xbacklight.

xbacklight -set 100

Herr

Answer 3

On my machine I run the following as root:

echo -n 10 > /sys/devices/virtual/backlight/acpi_video0/brightness

Downrange

This is what I use, but typing this command each time is a pain, so you might want to add a shell function to your .bashrc file, something like function brightness() { echo $1 > /sys/class/backlight/acpi_video0/brightness } – Jujube

I got echo: write error: Invalid argument when I tried this. You may need to check /sys/class/backlight/acpi_video0/max_brightness first. I turned out that for me max_brightness was 7. – Prescriptive

It works, but brightness 0 only results in a darker screen, not in blank dark screen (like turn off) !!! Any idea why ? – Hypogastrium

Answer 4

For me it works perfectly with xbacklight. If you for example wish to set up a key binding, you can use

bindsym $SUPER+Shift+plus   exec  xbacklight -inc 10
bindsym $SUPER+Shift+minus  exec  xbacklight -dec 10

in your window managers config (I use i3) to regulate your screen's brightness level.

I wouldn't recommend xrandr for this since it doesn't stop at 100% brightness automatically.

Tactical

Answer 5

The ddcutil application can change an external monitor's actual backlight brightness via the VESA DDC/MCCS standard (xrandr can only move the X11 output within a monitor's currently set limits, it can't change the actual backlight brightness). This should work for any monitors that support that capability via Display Data Channel (DDC has been around for some time, it is be widely supported, but for external monitors only). I use ddcutil to automatically adjust my monitor based on the ambient light level sampled from a webcam. Ddcutil uses the i2c-dev kernel module (modprobe i2c-dev or set it to load at boot).

ddcutil detect                    # Get list of DDC displays
ddcutil --display 2 capabilities  # List VCP feature key numbers
ddcutil --display 2 getvcp 10     # Get brightness by key number
ddcutil --display 2 setvcp 10 50  # Set brightness to 50                                                                            

Kelleekelleher

Subsequent to answering this question, I have written my own desktop tray GUI front end to ddcutil specifically for quick access to backlight adjustments. If you need such a tool, see vdu_controls at github.com/digitaltrails/vdu_controls or the brief write up at forums.opensuse.org/showthread.php/… – Kelleekelleher

Answer 6

You might look into using xgamma. Although it's not pure code, at least it's just a command line utility.

Adaminah

xgamma is not a monitor brightness, it is image filtering before output it into VGA card. – Flock

Answer 7

edit /etc/default/grub file and add

“pcie_aspm=force acpi_backlight=vendor” after

GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash”

after the changes, the whole line will look like this

GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash pcie_aspm=force acpi_backlight=vendor”

Chirag Singh

Oscar

Answer 8

If you have multiple displays and php installed, put this in

/usr/bin/brightness

#!/usr/bin/php
<?
$br=(double)$argv[1];
if(!$br||$br>1) die("enter brightness lvl 0.1 - 1");
preg_match_all('!^(\S+)!m',`xrandr --current | grep ' connected'`,$m);
foreach($m[1] as $display){
        echo `xrandr --output $display --brightness $br`."\n";
}

than call brightness .7

Punkah

Answer 9

Here is the simple step to control brightness in Linux based system

First, you have to know the monitoring screen connected you.

To know this run this command

xrandr -q

It will give useful information about the screen

( Here my screen connected to eDP, It might be different for your system )

After knowing that run the below command

xrandr --output eDP --brightness [0-10]

Replace eDP by your connected screen from the above output.

you can choose normal brightness values from 0.1 to 1.0

Potts

Answer 10

command for this:

xgamma -gamma 0.7

Denotation

Answer 11

Works only for intel, but you can use xbacklight. Create a /etc/X11/xorg.conf.d/20-intel.conf and then add

Section "Device"
    Identifier  "Intel Graphics"
    Driver      "intel"
    Option      "Backlight"  "intel_backlight"
EndSection

Reboot, and then you can use xbacklight -set somevalue

Mcmullan