If you speak German but prefer using an English keyboard layout for programming (dvorak in my case), then you will frequently face the issue of how to conveniently enter Umlaute.
Luckily, there's an easy solution with xmodmap, just add the below to your
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clear mod1 keycode 108 = Mode_switch add mod1 = Alt_L keysym a = a A adiaeresis Adiaeresis keysym o = o O odiaeresis Odiaeresis keysym u = u U udiaeresis Udiaeresis keysym s = s S ssharp
Where 108 is the keycode returned by
xev for your Alt key.