Umlauts in Ubuntu

This is a recurring and extremely annoying problem. If you want to (reliably) type Umlauts via PuTTy on a Ubuntu machine, you need to do two things:

On your Windows-machine, make sure that the PuTTy setting "Window"->"Translation" -> "Remote Character Set" is set to "UTF-8".

On your Ubuntu machine that you want to connect to, make sure that the "locale" is set to something UTF-8 compatible.

locale

Gives you the current settings. For me, it used to say a bunch of POSIX stuff. To change that, first do

locale -a

to see the installed locales. If your preferred locale is not there, do

sudo locale-gen en_US.UTF-8
update-locale LANG=en_US.UTF-8

The last command creates a file /etc/default/locale that contains the line LANG=en_US.UTF-8. This environment variable is what sets the locale of your system.