cannot connect to x server error

Question

I have a camera application which I am trying to run under sudo: but I am receiving this error

cannot connect to x server

the issue is when I dont use sudo, the program opens fine. However, there are certain parts of this application which still need admin privileges.

Since it is a GUI application, I tried to use gksudo then it opens a window asking about the password, but after entering the password the application returns and GUI does not open!

I have tried also

sudo xhost local:root

and got:

xhost: unable to open display""   

I am using lubuntu 14.04

Answer 1

This answer is a cannon to kill a rabbit, but if all you're interested in sudoing X applications that is what you'll need.

The solution:

Add to your ~/.bashrc

# Fabby: 2014-11-14: http://askubuntu.com/questions/571116/
# to allow forwarding of xauth keys between users when calling su
# needs to be the last line
export $(dbus-launch)

The explanation:

• Do you know what the X server is? OK!
• Do you know that it has a client/server technology? OK!
• Do you know what D-Bus is? OK!
• Well, now the dbus-launch variable gets exported so that x messages from one user session can use other user's session! Plain and simple!

Answer 2

I am using SecureCRT as ssh tool, however it cannot display some plots on local host with Windows OS. I have the same problem when using Canopy.

Solutions:

1. Install Xmanager, running Xmanager Passive.
2. Add "export DISPLAY=your ip:0.0" in ~/.bashrc, source ~/.bashrc (ip is your host IP, where you wanna display plots or things like that. If you are using Windows, cmd-ipconfig, find your IP).
3. Test (i.e. $xclock, you can see a clock in your windows screen) or directly test your own GUI applications.

Done!