/usr/ is in ruby-dataobjects-mysql 0.10.16-2ubuntu3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/do_mysql/
/usr/lib/ruby/vendor_ruby/do_mysql/encoding.rb
/usr/lib/ruby/vendor_ruby/do_mysql/transaction.rb
/usr/lib/ruby/vendor_ruby/do_mysql/version.rb
/usr/lib/ruby/vendor_ruby/do_mysql.rb
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/ruby/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.5.0/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.5.0/do_mysql/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.5.0/do_mysql/do_mysql.so
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-dataobjects-mysql/
/usr/share/doc/ruby-dataobjects-mysql/README.markdown
/usr/share/doc/ruby-dataobjects-mysql/changelog.Debian.gz
/usr/share/doc/ruby-dataobjects-mysql/copyright
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/2.5.0/
/usr/share/rubygems-integration/2.5.0/specifications/
/usr/share/rubygems-integration/2.5.0/specifications/do_mysql-0.10.16.gemspec