Error run gui prigram at debian (QXcbConnection Could not connect to display)

[VLeshka]

Hi!

I have compile the gui program by QT5.9 (sudo apt install qt5-default).

The compiling complete finely at lxqt and debian9:

sudo apt install qt5-default

cd program_directory

make clean

make

At lxqt, the binary program runs finely. But lxqt take up too much space, so I need in debian9.

But at debian9, running the binary file returns an error:

QXcbConnection: Could not connect to display

I have made:

export DISPLAY=:0.0

sudo apt install libffi-dev phantomjs gksu

But the error is still present.

Also I can run the gui program at debian9 from another PC by:

ssh -X 192.168.X.X -l debian

but this doesn't solve the problem.

Please help.

[Dennis Lee Bieber]

On Tue, 31 Mar 2020 12:04:54 -0700 (PDT), in
gmane.comp.hardware.beagleboard.user "'VLeshka' via BeagleBoard"

<beagleboard-/JYPxA39Uh5...@public.gmane.org> wrote:

>Hi!
>I have compile the gui program by QT5.9 (sudo apt install qt5-default).
>The compiling complete finely at lxqt and debian9:

LXQT is a Desktop Environment running ON some OS; Debian is an OS.

The LXQT image http://beagleboard.org/latest-images IS Debian 9 (AKA:
Stretch), with the additional packages needed to run an X server (display).
The IoT image there does not have a desktop environment or X server.

>
>At lxqt, the binary program runs finely. But lxqt take up too much space,
>so I need in debian9.
>But at debian9, running the binary file returns an error:
>QXcbConnection: Could not connect to display
>

You are going to have to add enough stuff to provide, at minimum, an X
server implementation -- and most likely you'll need a window/desktop
manager.

Many years ago, BBB used LXDE, which is supposed to be a lighter-weight
system https://en.wikipedia.org/wiki/LXDE

You might be able to build the components you need (at the least,
session manager and display manager, along with X-Window server). Note
however that LXQT was derived from LXDE replacing GTK+ with Qt; so may not
gain all that much reverting to just LXDE.

>Also I can run the gui program at debian9 from another PC by:
>ssh -X 192.168.X.X -l debian
>but this doesn't solve the problem.
>

Because that "another PC" is providing the X server (the display
system). Your program is only a client sending X-window commands to the
system that has the display/server capability.


--
Dennis L Bieber