When running sudo commands such as sudo dolphin I'm getting this strange error:
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
What does it mean and how can I fix it?
I think I got this error since install and I did not change any standard paths or something alike: I'm still new to GNU/Linux.
I'm running Debian 9.1 with KDE.
Edit: you should never run Dolphin with sudo! This allows vulnerabilities in the file-explorer to be exploited. You shouldn't run most other GUIs as root either (these should only prompt you for your sudo password).