If I'd like to kill all instances of that file manager, I'd do
killall thunar
which gives me
thunar: no process found
But this FM is definitely running!
Similarly ps aux | grep thunar
doesn't find anything and yields:
cadoiz 27791 0.0 0.0 9588 2656 pts/0 S+ 11:33 0:00 grep --color=auto thunar
killall
seems to be case sensitive and for some reason, Thunar
with capital T
works:
killall Thunar
You can consider this debian forum discussing the topic.