/usr/lib/ruby/1.9.1/rake/ is in libruby1.9.1 1.9.3.0-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/1.9.1/rake/alt_system.rb
/usr/lib/ruby/1.9.1/rake/application.rb
/usr/lib/ruby/1.9.1/rake/classic_namespace.rb
/usr/lib/ruby/1.9.1/rake/clean.rb
/usr/lib/ruby/1.9.1/rake/cloneable.rb
/usr/lib/ruby/1.9.1/rake/contrib/
/usr/lib/ruby/1.9.1/rake/contrib/compositepublisher.rb
/usr/lib/ruby/1.9.1/rake/contrib/ftptools.rb
/usr/lib/ruby/1.9.1/rake/contrib/publisher.rb
/usr/lib/ruby/1.9.1/rake/contrib/rubyforgepublisher.rb
/usr/lib/ruby/1.9.1/rake/contrib/sshpublisher.rb
/usr/lib/ruby/1.9.1/rake/contrib/sys.rb
/usr/lib/ruby/1.9.1/rake/default_loader.rb
/usr/lib/ruby/1.9.1/rake/dsl_definition.rb
/usr/lib/ruby/1.9.1/rake/early_time.rb
/usr/lib/ruby/1.9.1/rake/ext/
/usr/lib/ruby/1.9.1/rake/ext/core.rb
/usr/lib/ruby/1.9.1/rake/ext/module.rb
/usr/lib/ruby/1.9.1/rake/ext/string.rb
/usr/lib/ruby/1.9.1/rake/ext/time.rb
/usr/lib/ruby/1.9.1/rake/file_creation_task.rb
/usr/lib/ruby/1.9.1/rake/file_list.rb
/usr/lib/ruby/1.9.1/rake/file_task.rb
/usr/lib/ruby/1.9.1/rake/file_utils.rb
/usr/lib/ruby/1.9.1/rake/file_utils_ext.rb
/usr/lib/ruby/1.9.1/rake/gempackagetask.rb
/usr/lib/ruby/1.9.1/rake/invocation_chain.rb
/usr/lib/ruby/1.9.1/rake/invocation_exception_mixin.rb
/usr/lib/ruby/1.9.1/rake/lib/
/usr/lib/ruby/1.9.1/rake/lib/project.rake
/usr/lib/ruby/1.9.1/rake/loaders/
/usr/lib/ruby/1.9.1/rake/loaders/makefile.rb
/usr/lib/ruby/1.9.1/rake/multi_task.rb
/usr/lib/ruby/1.9.1/rake/name_space.rb
/usr/lib/ruby/1.9.1/rake/packagetask.rb
/usr/lib/ruby/1.9.1/rake/pathmap.rb
/usr/lib/ruby/1.9.1/rake/pseudo_status.rb
/usr/lib/ruby/1.9.1/rake/rake_module.rb
/usr/lib/ruby/1.9.1/rake/rake_test_loader.rb
/usr/lib/ruby/1.9.1/rake/rdoctask.rb
/usr/lib/ruby/1.9.1/rake/ruby182_test_unit_fix.rb
/usr/lib/ruby/1.9.1/rake/rule_recursion_overflow_error.rb
/usr/lib/ruby/1.9.1/rake/runtest.rb
/usr/lib/ruby/1.9.1/rake/task.rb
/usr/lib/ruby/1.9.1/rake/task_argument_error.rb
/usr/lib/ruby/1.9.1/rake/task_arguments.rb
/usr/lib/ruby/1.9.1/rake/task_manager.rb
/usr/lib/ruby/1.9.1/rake/tasklib.rb
/usr/lib/ruby/1.9.1/rake/testtask.rb
/usr/lib/ruby/1.9.1/rake/version.rb
/usr/lib/ruby/1.9.1/rake/win32.rb