~/project/connection을 ~/project/source_file을 가리키는 symbolic link로 만드는 명령은 무엇인가요?
~/project/connection
~/project/source_file
ln -s ~/project/source_file ~/project/connection
ln -s ~/project/connection ~/project/source_file
readlink ~/project/source_file ~/project/connection
ln ~/project/source_file ~/project/connection