When I am running some software using sudo command it showing error like

cannot connect to X server

For example if I run the following command:

$ sudo gedit /etc/profile

I am getting following command

(gedit:6758): WARNING **: Command line `dbus-launch --autolaunch=84b871d735f31ffe014dc9ba00000009 --binary-syntax --close-stderr' 

exited with non-zero exit status 1: 

Autolaunch error: X11 initialization failed. 

Cannot open display:

Run 'gedit --help' to see a full list of available command line options.

Or if I am running super-boot-manager I am getting following error

buc: cannot connect to X server

Please help.