Попробуйте что-то вроде этого:

# Put each code in one line, and sort them
sed -e 's/\ /\n/g' new | sort > neweans
sed -e '/s\ /\n/g' master | sort > mastereans

# Diff them by columns, and delete from the list
# the new's that are not in master. Then, print them

diff -y neweans mastereans | grep -v "<" | awk '{print $1}'