Creating a custom keyboard layout with umlauts on alt + ctrl

Question

I'm trying to create a custom keyboard layout to fit my needs, based on the US layout.

What I want

• Alt + Ctrl + u = ü
• Alt + Ctrl + Shift + u = Ü

(same way for ö, ä, and ß)

Why?

1. Because getting used to the German keyboard is not how I want to waste my time
2. The hotkeys for the international one aren't convenient for me
3. Installing 3rd party software like autokey is not a good idea either: it's another daemon running somewhere instead of the kb being native (but layout editor is an ok solution)

System

Xubuntu (Ubuntu + Xfce) 22.04

What I've tried

There quite a lot of answers on this forum for this question. Many just go with the available layots.

• There's a guide, but it doesn't answer how to bind it on alt+ctrl (or I didn't get)
• There's KeyboardLayoutEditor, but unfortunately it requires python 2
• There's even @cuppajoeman's keyboard layout generator, but it creates a new layout

And there are more I tried, that are either too complex, or me too stupid/lazy. If there's a good guide on what I want to actually do, I'd be very thankful.

Answer 1

It turned out that even with regular US layout you can do

• Compose + " + u = ü
• Compose + " + U = Ü
• Compose + " + a = ä
• Compose + " + A = Ä
• Compose + " + o = ö
• Compose + " + O = Ö
• Compose + s + s = ß
• Compose + S + S = ẞ

and I guess I'm satisfied with that. To set the compose key, go to keyboard -> layout, there's a dropbox for changing the compose key

Answer 2

cat /usr/share/X11/xkb/symbols/us

 key <AD07> { [ u, U, NoSymbol, NoSymbol, udiaeresis, Udiaeresis ] }; 

Set your CTL+ALT as a level5 shift and CTL+ALT+SHIFT would be a level6 shift.