xset: unable to open display

Question

For the longest time after about 5 minutes my screen would blank out. Now the screen will go blank after 5 minutes but then 2 seconds after that it will light up white and keep the laptop backlighting on. I didn't change any settings to my knowledge it just happened randomly after powering it on one day and has occurred since then.

I wish to resort back to blanking the screen out completely since I leave this computer on all the time and it's hard to sleep with a huge white light all the time.

xset dpms force off just yields me:

xset:  unable to open display ""

Solution 1

You need to tell xset which display to use:

export DISPLAY=:0
xset q

Solution 2

Try vbetool instead xset:

sudo vbetool dpms off

It's works fine for me.

Comments

[KeyTrap]

> export DISPLAY=:0 > xset q after that I have ' unable to open display ":0" '

[Nikolay Ruban]

Had same problem when was trying to access monitor remotely with user other than logged in.

[yode]

Then I get xset: unable to open display ":0"

[KRoy]

export DISPLAY=0 instead. It should work

[bitdancer]

Sorry I got the error "Real mode call failed"

[Seff]

Neither of the methods works in systemd foked process.

[TimNode]

For me a combination of sudo & running the normal command worked. Combination of export DISPLAY=:0 and sudo xset q. Pretty weird.

[Admin]

I got "Failed to initialise LRMI (Linux Real-Mode Interface)."