My external screen is too bright, even on the lowest brightness setting. Too dampen the brightness, I am trying to use xrandr --output HDMI2 --brightness 0.5 as detailed in this post How do dim screen, even if artifically, below the minimum?.

However, while this command does lower the brightness, the screen switches back to the brighter level in an instant. Basically, the screen blinks once in a darker brightness. I tried with my primary laptop screen, xrandr --output eDP1 --brightness 0.5, with the same outcome. I also tried changing the gamma, xrandr --output eDP1 --gamma 1.0:1.0:0.5, again with the same transient result, this time a one second flash in a yellow tint.

How can I make xrandr modifications persist until I specifically change it? If it persists through reboot or not isn't a big deal.

My xrandr is version 1.5.0 and I am on Antergos Linux (an Arch derivative) with Gnome 3.20.2 and kernel 4.6.2-1.

  • It might be your desktop environment imposing its own configuration. What desktop environment are you using? Do you have the same problem with a different account using a different desktop environment? Jun 27, 2016 at 21:22
  • I am using Gnome 3.20.2, updated the question. I don't have any other desktop manager installed, but I tried in a Gnome Wayland session. In Wayland, the same xrandr command produces no visible output, not even a flicker of the screen as previously. Jun 28, 2016 at 2:28
  • 1
    ´xrandr´ shouldnt affect a Wayland desktop because its not an x server. Well, it might if the Wayland session is run atop an x server, which i guess might explain the flash you mentioned in a comment on the other question.
    – mikeserv
    Jun 29, 2016 at 3:42
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    @mikeserv Thanks for explaining why xrandr is not affecting the Wayland desktop session. The flash I am seeing is only happening in the Gnome and Gnome Classic session, which I guess both run the xserver. I still don't understand what is causing the flash and preventing the xrandr changes from persisting. Jun 29, 2016 at 13:41

1 Answer 1


What you want, is to set the backlight to your desired value. Since you are on Gnome 3, you might want to change it in Gnome.

gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.freedesktop.DBus.Properties.Set org.gnome.SettingsDaemon.Power.Screen Brightness "50"

If that does not work, the ArchWiki has many alternatives, including ACPI and kernel parameters ...

Select your monitors in the following:

# ls /sys/class/backlight/

inspect the maximum brightness:

# cat /sys/class/backlight/<device>/max_brightness

Then you set it to your desired value:

# echo 5 > /sys/class/backlight/acpi_video0/brightness

Source (ArchWiki): https://wiki.archlinux.org/index.php/backlight

DISCLAIMER: I do not run Gnome 3, so cannot test this.

  • Thanks for your answer! I have since stopped using an external screen, so this haven't been an issue for me lately. I have also moved to i3, so I am not able to validate whether this works with the setup I originally described in my question, sorry about that. Oct 28, 2017 at 16:41

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