I installed Ubuntu server 20.04 on old, damaged laptop. The problem is, that I can not close the cover - this is the "damaged" part of the problem.

Is there any way to turn off the screen via command line?

I found such solution: sudo vbetool dpms off, but it does not work and returns error:

mmap /dev/zero: Operation not permitted
Failed to initialise LRMI (Linux Real-Mode Interface)

How can I turn off the screen? Is it even possible with command line only?

  • I believe there is now no s/w solution to this but on a laptop, isn't there a fn key which deselects the screen and ports to an external monitor? If none is attached, does that perform what you seek to achieve?
    – 24601
    Sep 24, 2020 at 16:58
  • There is an fn key that should turn off the screen, but it does not work with command line only. It did work with windows, and I belive that it probably would work with x-ubuntu, but I have command line only. I belive that it should be possible to somehow "install" and use this function, since it is there... byt how to reach it - I have no idea.
    – Zorann
    Sep 24, 2020 at 17:06
  • 1
    There's no accepted solution in this reference but it may help askubuntu.com/questions/62858/…
    – 24601
    Sep 24, 2020 at 17:45
  • @Zorann When you say you "have command line only", are you referring to the tty device terminals? (You're not using graphical terminal emulators in X11/Wayland? And you're not logging in remotely?)
    – xiota
    Sep 24, 2020 at 18:03
  • @xiota I'm new with linux so I'm not familiar with those terms, but Yes - I have no graphical interface, only command line. I'm logging in via putty from windows computer.
    – Zorann
    Sep 24, 2020 at 18:30

1 Answer 1


I had the same issue on Ubuntu 20.04 LTS server.

$ sudo vbetool dpms off

mmap /dev/zero: Operation not permitted
Failed to initialise LRMI (Linux Real-Mode Interface)

Finally I found the solution here.

You have to use 2 extra command.

In order:

sudo mount -o remount,exec /dev
sudo vbetool dpms off
sudo mount -o remount,noexec /dev

To turn on again the display:

sudo mount -o remount,exec /dev
sudo vbetool dpms on
sudo mount -o remount,noexec /dev
  • I actually can`t belive it! I was sure that it was a lost case. I know that I should add an comment about the topic rather than just thank You, but for me it is just amazing! You just make me happy today :)
    – Zorann
    Jul 12, 2021 at 19:01
  • That's the power of community. We help each other when we can :)
    – Belushi
    Jul 13, 2021 at 13:54

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