cannot connect to x server

[cec]

Hello,

When I do a ssh on my machine and I try to run an application, it gives me the following error :

cannot connect to x server.

What can I do?

Thank you for your help

[Dapper Dan]

You are logging into this machine from another via ssh? The address of the server has to be preceded with either -Y or -X. Log into the server with:
*Example*

ssh -Y bob@bobsnetwork

Then, run the command for the app or utility you wish to run. If -Y doesn't work, try -X. If you still cannot get X forwarded you will likely have to edit /etc/ssh/sshd_config. Open sshd_config on the server with your favourite editor and look for:

#X11Forwarding no

...and change to:

X11Forwarding yes

Restart sshd on the server or reboot and X forwarding should then be enabled.

[cec]

I've connected with -X but I always have the same error.

My sshd_config already had X11Forwarding to yes.

[Dapper Dan]

Did you try -Y ? Are you by chance trying to run the application as root or su?

[cec]

I tried -Y but it does the same.

No I am not running the application as root.

[Dapper Dan]

Perhaps a few more dumb questions... Is the X server actually running on the server machine? Are you trying to run an application remotely or are you trying to run a desktop environment from the server to a client machine? Please give more detail about what you are attempting to do and the commands you are using to do it.

[cec]

The X server isn't actually running on the server machine.

I'm doing a ssh -X mymachine and then I'm trying to run my application remotly.

[Dapper Dan]

Then there's your problem. You cannot forward X from a server machine to a client if X isn't running on the server.

[cec]

but when I run X server on my server, it doesn't change anything. I always have my error.

[Dapper Dan]

Is this a headless server or does it have a monitor? If a monitor, are you able to bring up xwindows from it and it works satisfactorily?