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zx485
Asked: 2024-10-19 03:14:34 +0800 CST

How to turn OFF (and ON) a single monitor in a multiple-monitor-system on Kubuntu 24.10 (with Wayland)?

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This could be achieved with X easily, but although looking extensively on AskUbuntu and other sites, I did not find a solution for Wayland :-(

The closest I came to was the command kscreen-doctor --dpms off. Unfortunately this turns off all monitors at once. But I'm looking for a more granular command that can turn on/off a single monitor alone.

Some posts suggest that this depends on the compositor. So I checked which compositor Kubuntu 24.10 uses with inxi -Gxx | grep compositor and the output is:

compositor: kwin_wayland driver: X: loaded: modesetting unloaded: fbdev,vesa

But what command or command-line-tool can I use to achieve the given task?

multiple-monitors

1 Answers

  1. Best Answer

    As suggested in the comments, this can be achieved with the command line utility ddcutil. Install it with

    sudo apt install ddcutil

    and then enumerate your monitors with

    ddcutil detect

    The output contains a sequential monitor number like Display 1, a bus address like /dev/i2c-2 and a serial number like 1138753042236 besides other information like the name of the manufacturer and so on.

    Display 1
   I2C bus:  /dev/i2c-2
   DRM connector:           card1-HDMI-A-1
   EDID synopsis:
      Mfg id:               IVM - Iiyama North America
      Model:                PLE2483H-DP
      Product code:         24862  (0x611e)
      Serial number:        1138753042236
      Binary serial number: 2236 (0x000008bc)
      Manufacture year:     2017,  Week: 30
   VCP version:         2.1

    Each of these values can be used to address the monitor whose state you like to change. To turn a monitor on, pass the value 1 to the VCP 0xD6, and to turn it off, pass the value 2 respectively. So specify the monitor and then the value for ON/OFF.

    For example, to turn off display/monitor 1 by sequential number, use

    ddcutil setvcp -d 1 0xd6 2

    And to turn it off by serial number to make it independent of enumeration, use

    ddcutil setvcp --sn 1138753042236 0xd6 2

    and to turn it on again

    ddcutil setvcp --sn 1138753042236 0xd6 1

    There are a lot of other options that can be configured this way, but turning a monitor on and off is the most basic option.

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