/usr/ is in ruby-unf-ext 0.0.7.4-1build2.
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/unf_ext/
/usr/lib/ruby/vendor_ruby/unf_ext/version.rb
/usr/lib/ruby/vendor_ruby/unf_ext.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/unf_ext.so
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-unf-ext/
/usr/share/doc/ruby-unf-ext/README.md
/usr/share/doc/ruby-unf-ext/changelog.Debian.gz
/usr/share/doc/ruby-unf-ext/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/unf_ext-0.0.7.4.gemspec
/usr/share/doc/ruby-unf-ext/CHANGELOG.md.gz