I have a 4.3inch DSI LCD fro Waveshare. If you want to see the home page
it is here

https://www.waveshare.com/wiki/4.3inch_DSI_LCD?Amazon

I am trying to blank the screen remotely via SSH and the instructions
say use

xset dpms force off

However this results in the error xset: unable to open display ""

Any ideas??

Dr Stephen Strange wrote:

> xset dpms force off

Any difference if you use an explicit display number? e.g

xset -display :0.0 dpms force off
xset -display :1 dpms force off

Andy Burns wrote:
> Dr Stephen Strange wrote:
>
>> xset dpms force off
>
> Any difference if you use an explicit display number? e.g
>
> xset -display :0.0 dpms force off
> xset -display :1 dpms force off

using the first one I get - server does not have extension for dpms option
xset: unknown option force

And using the second I get - xset: unable to open display ":1"

On 08/08/2023 13:39, Dr Stephen Strange wrote:
> I have a 4.3inch DSI LCD fro Waveshare. If you want to see the home page
> it is here
>
> https://www.waveshare.com/wiki/4.3inch_DSI_LCD?Amazon
>
> I am trying to blank the screen remotely via SSH and the instructions
> say use
>
> xset dpms force off
>
> However this results in the error xset:  unable to open display ""
>
> Any ideas??
wild guess:

sudo xset dpms force off

--
"Nature does not give up the winter because people dislike the cold."

― Confucius

The Natural Philosopher wrote:
> sudo  xset dpms force off

I tried sudo in fron of all the above commands with the same results

sudo xset dpms force off gives xset: unable to open display ""

My skill in these things is limited as you have probaly guessed!!!

On Tue, 08 Aug 2023 16:00:22 +0100, Dr Stephen Strange wrote:

> The Natural Philosopher wrote:
>> sudo  xset dpms force off
>
> I tried sudo in fron of all the above commands with the same results
>
> sudo xset dpms force off gives xset: unable to open display ""
>
> My skill in these things is limited as you have probaly guessed!!!

xset(1) is a utility supplied with and for X11, and requires
a) running X server,
b) a known display on that X server, and
c) permissions to access and modify that display.

If you try to use xset(1) to blank a screen, you have to specify
the display that the screen is attached to, and give permission
(either implicitly, by "owning" that display, or explicitly
through xauth(1) or another recognized authorization method)
for the xset(1) client application to access that display.

All to say that xset(1) is /not/ the best tool to use to blank a
screen remotely.

What you likely need is to use vbetool(1) or some other video
hardware state altering tool (perhaps setterm(1) would do) to
set the low-level video blanking values.

HTH
--
Lew Pitcher
"In Skills We Trust"

On a sunny day (Tue, 8 Aug 2023 14:07:32 +0100) it happened Dr Stephen Strange
<no.spam@me.com> wrote in <lFudnbNQIb-Jo0_5nZ2dnZfqnPqdnZ2d@brightview.co.uk>:

>Andy Burns wrote:
>> Dr Stephen Strange wrote:
>>
>>> xset dpms force off
>>
>> Any difference if you use an explicit display number? e.g
>>
>> xset -display :0.0 dpms force off
>> xset -display :1 dpms force off
>
>using the first one I get - server does not have extension for dpms option
>xset: unknown option force
>
>And using the second I get - xset: unable to open display ":1"

Seem dpms is not supported

How about
To stat screen saver on one second
xset -display :0.0 s 1

To set timout screen saver to 1000 seconds and disable it
xset -display :0.0 s 1000 s reset

See man xset

I am not sure that if some thing like mplayer is running it will blank
Also dpms may switch the backlight of the LCD off?
Does xset s do that ?
But just to blank against burnin this may work.