/usr/ is in ruby-shadow 2.2.0-1.
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/1.9.1/
/usr/lib/ruby/vendor_ruby/1.9.1/x86_64-linux/
/usr/lib/ruby/vendor_ruby/1.9.1/x86_64-linux/shadow.so
/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/2.0.0/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.0.0/shadow.so
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-shadow/
/usr/share/doc/ruby-shadow/README
/usr/share/doc/ruby-shadow/README.euc
/usr/share/doc/ruby-shadow/copyright
/usr/share/doc/ruby-shadow/changelog.Debian.gz
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/1.9.1/
/usr/share/rubygems-integration/1.9.1/specifications/
/usr/share/rubygems-integration/1.9.1/specifications/ruby-shadow-2.2.0.gemspec
/usr/share/rubygems-integration/2.0/
/usr/share/rubygems-integration/2.0/specifications/
/usr/share/rubygems-integration/2.0/specifications/ruby-shadow-2.2.0.gemspec