I am currently having problems with util-linux's look in combination with German umlauts (ä, ö, ü). For testing purposes I set LC_ALL=de_DE.UTF-8.
Consider german.dic:
Aachen
Rindfleisch
in UTF-8 encoding:
$ file german.dic
german.dic: UTF-8 Unicode text
If I try to find the second word with /usr/bin/look, it works perfectly fine:
$ look Rindf german.dic
Rindfleisch
Even if I add a word with a German umlaut (ä) inside the word look still works as expected:
$ cat german.dic
Altäster
Rindfleisch
$ look Rindf german.dic
Rindfleisch
However, if there is a word with a umlaut at the beginning:
$ cat german.dic
Ältester
Rindfleisch
$ look Rindf german.dic
It does not matter whether it's an uppercase or lowercase umlaut.
I've tried setting LC_ALL=de_DE.UTF-8 (which is definitely installed on my system) too, which did not work.