$ grep "logged in" server.log | awk '{print $4}' | sed 's/\[.*\]$//' | sort -u
_Akino_
barbelTV
Batch10s
Calvin21356
Chriseeej
ConiKost
crazycusti
crouvean
DosAmp
freakedenough
gandro
geiger2006
grundflitzerin
Hobbybaster
kthrss
Oetzi666
Sharky00
Su15
thosch97
tk1908
tlercher
Unlix
xCtrl