/usr/ is in ruby-extlib 0.9.16-1.
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/extlib.rb
/usr/lib/ruby/vendor_ruby/extlib/
/usr/lib/ruby/vendor_ruby/extlib/try_dup.rb
/usr/lib/ruby/vendor_ruby/extlib/class.rb
/usr/lib/ruby/vendor_ruby/extlib/assertions.rb
/usr/lib/ruby/vendor_ruby/extlib/hash.rb
/usr/lib/ruby/vendor_ruby/extlib/symbol.rb
/usr/lib/ruby/vendor_ruby/extlib/string.rb
/usr/lib/ruby/vendor_ruby/extlib/lazy_module.rb
/usr/lib/ruby/vendor_ruby/extlib/time.rb
/usr/lib/ruby/vendor_ruby/extlib/datetime.rb
/usr/lib/ruby/vendor_ruby/extlib/object.rb
/usr/lib/ruby/vendor_ruby/extlib/array.rb
/usr/lib/ruby/vendor_ruby/extlib/mash.rb
/usr/lib/ruby/vendor_ruby/extlib/byte_array.rb
/usr/lib/ruby/vendor_ruby/extlib/inflection.rb
/usr/lib/ruby/vendor_ruby/extlib/lazy_array.rb
/usr/lib/ruby/vendor_ruby/extlib/pooling.rb
/usr/lib/ruby/vendor_ruby/extlib/boolean.rb
/usr/lib/ruby/vendor_ruby/extlib/simple_set.rb
/usr/lib/ruby/vendor_ruby/extlib/hook.rb
/usr/lib/ruby/vendor_ruby/extlib/object_space.rb
/usr/lib/ruby/vendor_ruby/extlib/numeric.rb
/usr/lib/ruby/vendor_ruby/extlib/blank.rb
/usr/lib/ruby/vendor_ruby/extlib/dictionary.rb
/usr/lib/ruby/vendor_ruby/extlib/struct.rb
/usr/lib/ruby/vendor_ruby/extlib/pathname.rb
/usr/lib/ruby/vendor_ruby/extlib/nil.rb
/usr/lib/ruby/vendor_ruby/extlib/virtual_file.rb
/usr/lib/ruby/vendor_ruby/extlib/logger.rb
/usr/lib/ruby/vendor_ruby/extlib/module.rb
/usr/lib/ruby/vendor_ruby/extlib/local_object_space.rb
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-extlib/
/usr/share/doc/ruby-extlib/copyright
/usr/share/doc/ruby-extlib/changelog.Debian.gz
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/all/
/usr/share/rubygems-integration/all/specifications/
/usr/share/rubygems-integration/all/specifications/extlib-0.9.16.gemspec