Cannot connect to X Server when running app with sudo

Question

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.

Solution 1

You need to allow the root user access to the X server:

xhost local:root

And point the command to the right DISPLAY:

sudo DISPLAY=$DISPLAY gedit /etc/profile

Solution 2

Finally the problem is solved. I have just added the line:

Defaults env_keep="DISPLAY XAUTHORITY"

at the end of visudo.

To do that you have to run

sudo visudo

it will open the file then add the above line at the end.

Thanks to all, specially @Thor for kind help

Solution 3

Supplementing @Thor's answer:

Run xhost local:root before sudo gedit. To make this permanent, add the line

xhost local:root

to the file ~/.xinitrc ¹. Create the file if it doesn't exist.

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[1] https://askubuntu.com/a/720120/452398

Comments

[noobcoder]

That solved the problem with opening gedit as sudo, but still can't lunch super-boot-manager. It is showing same error

[sugab]

Defaults env_keep="DISPLAY" works for me.

[Ev-]

I have been searching high and low for this answer forever. I wish I could upvote both of you multiple times for your answers. Thank you so very much! :)

[user1927105]

Thank you for providing an answer that provides a non-permanent solution.

[jpaugh]

I've just learned that sudo -H should be used when starting graphical applications, to avoid file corruption of X-related files.

[Joerg S]

setting the DISPLAY in sudo was not even required for me - Debian Buster.

[user508402]

How can I make this permanent?

[Thor]

@user508402: that depends on many things. You should probably post this as a new question, where you detail your current setup, i.e. shell, window manager etc.