How to make xrandr modifications persist for more than 1 second

brightnessmulti-monitorxrandr

Updates:

This question describes similar symptoms Ubuntu – Xrandr doesn't change my resolution, but it seems like the underlying cause is different as there are no changes to my Xorg-log files in the last 6 months.
Another similar question without answer xrandr –pos doesn't do anything

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.

Best Answer

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.

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How to resolve “xrandr: cannot find crtc for output”

This occurs becaues you have another screen already active, in this case DP2. DP2 here is a monitor running off of a DisplayPort. The laptop is a Lenovo x230 and it was booted with an Ultrabase 3 docking station.

You can resolve this issue by simply turning off the screen using,

xrandr --output DP2 --off

Now, in XFCE or similar workstation you should see your desktop area shrink. Then you can continue running your xrandr commands as you normally would,

xrandr --auto
xrandr ...

linux-mint – How to get external monitor resolution set by xrandr to persist

I'm sure there's a better way, I think this is all handled by udev now but if you know that those commands will solve it, you could always just make them into a script:

#!/usr/bin/env bash
cvt 1600 1200
xrandr --newmode "1600x1200_60.00"  161.00  1600 1712 1880 2160  1200 1203 1207 1245 -hsync +vsync
xrandr --addmode VGA-1 1600x1200_60.00

Make it executable and then add it to your Desktop Environment's startup applications. This is probably the best choice if your DE provides you with the option.

If you can't do the above, as a dirty hack you could add them to your ~/.profile:

if [ ! -t 0 ] 
then
    cvt 1600 1200
    xrandr --newmode "1600x1200_60.00"  161.00  1600 1712 1880 2160  1200 1203 1207 1245 -hsync +vsync
    xrandr --addmode VGA-1 1600x1200_60.00
fi

The if [ ! -t 0 ] should ensure this is only run in the GUI and .profile is sourced by mint's login manager as I recall.

Now, you should also be able to use ~/.xsession but I've had issues with that being ignored. A lot of the older approaches are being replaced and I'm not sure what the state of the art way is.

Best Answer

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linux-mint – How to get external monitor resolution set by xrandr to persist

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