/usr/lib/ is in subtle 0.11.3224-xi-2.1.
This file is owned by root:root, with mode 0o755.
..
/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/2.1.0/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/subtlext.so
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/subtler/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/subtler/runner.rb
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/sur/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/sur/test.rb
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/sur/version.rb
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/sur/specification.rb
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/sur/client.rb
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/sur/server.rb
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.1.0/subtle/sur/runner.rb