<oerjan> le/rn Hungry//Hungry is a country in Europe, formerly part of the Ostrich empire. It split after a famine that got so severe that they had to start editing disgusting things like bell peppers. Absurdly, this became a tradition that continues until the present day.

sep="//"
[[ "$1" == ?*"$sep"* ]] || exit 1
topic="$(echo "${1%%$sep*}" | lowercase)"
stuff="${1#*$sep}"
perl -i -p -e 's/\n/ /' "wisdom/$topic"
echo "$stuff" >>"wisdom/$topic"
echo -n "Learned '$topic': "
cat "wisdom/$topic"