error: XDG_RUNTIME_DIR not set in the environment. Gtk-WARNING **: cannot open display:

Question

I used to open text files with sublime, and for Read-only files, I used to do : sudo sublime. But now just suddenly the sudo sublime command gives the following error :

(sublime:3931): Gtk-WARNING **: cannot open display:

while sublime command is working fine. I tried the same with gedit, and the same thing happened, with the error with gedit being shown :

error: XDG_RUNTIME_DIR not set in the environment.
(gedit:3933): Gtk-WARNING **: cannot open display: 

I installed gtk, and tried gksudo, still got the same error!

I searched the web and found these ways :

1. xhost +localhost : https://askubuntu.com/questions/614387/gksu-gtk-warning-cannot-open-display-0
2. export DISPLAY=:0.0 :
3. ssh username@hostname -X
4. ssh username@hostname -Y
5. How do I fix a "cannot open display" error when opening an X program after ssh'ing with X11 forwarding enabled?

None of the above worked.

What worked out for me was :

pkexec env DISPLAY=$DISPLAY XAUTHORITY=$XAUTHORITY sublime

From here : https://askubuntu.com/questions/456689/error-xdg-runtime-dir-not-set-in-the-environment-when-attempting-to-run-naut

I want to know why exactly am I getting this error, that too suddenly! Also, I want to get back to the sudo sublime version, since it is easy to remember. How can I fix that?

Also, the recent changes I did to the system were :

1. Installed Mac theme for Ubuntu : http://www.noobslab.com/2014/04/macbuntu-1404-pack-is-released.html

2. Installed gksu(for gksudo)

Help would be highly appreciated!

Answer 1

Any system updates lately... This sounds related. Maybe this

If you have something that works, you can always just put it in a shell script and keep that script in your path.
In Debian you can create a 'bin' directory in your home folder and that will automatically be included in your path; I'm not certain if it works on Ubuntu, but chances are good.

So in ~/bin create 'sublime-root.sh' and put your pkexec stuff in there?