Okular - Issues with User Root

 

When you log into Linux as a regular user, the system creates a graphical environment (windows, desktop, etc.) that belongs to your user account. This is called your "display" or "X session."

Each user account has its own separate display for security reasons - this way one user can't see what another user is doing on their screen. Even though user root has admin privileges, root is treated as a separate user and is blocked from accessing your display by default.

If you try to run Okular as root from within your user session using sudo or su, you will receive an error message.  The error message is generated because root doesn't have permission to draw windows on your screen. The application needs to connect to your display to show its window, but that connection is blocked.

Also many GUI applications like Okular are programmed to refuse running with root privileges altogether, regardless of whether root has its own graphical session. This is a safety feature built into the application itself. Running GUI applications as root is considered dangerous because a bug or vulnerability in the application could give an attacker complete control over the entire system. By refusing to run as root, the application protects the system from potential security risks.