KDE Kate editor - sort, shut up - turn off audio or sound, run as root

To sort lines:

1. Select the lines

2. Go to Settings -> Customize Kate -> Plugins and enable Textfilter, click OK until you're back at the text

3. Go to Tools -> Filter text

4. Enter "sort" in the text area and click OK.

Make it shut up - turn off audio or sound

If you in the Debian 11 MATE Desktop version of the Kate editor have an unsaved file and press Ctrl+W you will get an annoying chime sound that is hard to get rid of.

It does not obey the system sound effect settings in MATE.

To get rid of it you need to lower the sound effect setting in Plasma since Kate belongs to that desktop environment. And to do that you need to install Plasma desktop and the Plasma Pulseaudio settings.

sudo apt install plasma-desktop plasma-pa

Then run the settings dialog - note the lack of a plasma- prefix on the name of the program making it even harder to find:
systemsettings5

In the left tab go to Hardware, Audio/Sound.
Then the tab Program.
Then there is a slider under Playback streams named Event sounds or something, drag it down to 0%.

Then close the window. Note that the settings program crashes, pops up the KDE bug reporting program that as usual is completely useless since it as usual decides on its own that it has not gathered enough information to allow you to send the bug report to the developers even if the information it has gathered seems to be more than enough. Shameful.

Run Kate as root

If you run sudo bash and then kate you will get this junk:
Executing Kate with sudo is not possible due to unfixable security vulnerabilities.

You could run this instead of sudo bash:
su -

Starting kate then works without the error, but instead you get this:
	
qt.qpa.xcb: could not connect to display 
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.

Aborted (SIGABRT)

To fix this you will have to get the cookie set for the current user and the the DISPLAY environment variable, procedure to do this:

Note the output of the following:
xauth list $DISPLAY
echo $DSIPLAY

su -

xauth add <output from xauth list $DISPLAY>

export DISPLAY=<output from echo $DISPLAY>

kate

You now have kate started as root.

To start the shell in one line:

su - -c "xauth add $(xauth list $DISPLAY); DISPLAY=$DISPLAY /bin/bash"

Or if you only do it in a local shell without SSH you can ignore the xauth part:

su - -c "DISPLAY=$DISPLAY /bin/bash"

Then start kate:

kate

Source:
https://www.thegeekdiary.com/how-to-set-x11-forwarding-export-remote-display-for-users-who-switch-accounts-using-sudo/