/usr/lib/ruby/ is in ruby-librdf 1.0.17.1+dfsg-1.3build4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/2.5.0/
/usr/lib/ruby/2.5.0/rdf/
/usr/lib/ruby/2.5.0/rdf/redland/
/usr/lib/ruby/2.5.0/rdf/redland/constants.rb
/usr/lib/ruby/2.5.0/rdf/redland/convert_owl.rb
/usr/lib/ruby/2.5.0/rdf/redland/convertfoaf.rb
/usr/lib/ruby/2.5.0/rdf/redland/dc.rb
/usr/lib/ruby/2.5.0/rdf/redland/model.rb
/usr/lib/ruby/2.5.0/rdf/redland/node.rb
/usr/lib/ruby/2.5.0/rdf/redland/parser.rb
/usr/lib/ruby/2.5.0/rdf/redland/query.rb
/usr/lib/ruby/2.5.0/rdf/redland/queryresults.rb
/usr/lib/ruby/2.5.0/rdf/redland/resource.rb
/usr/lib/ruby/2.5.0/rdf/redland/schemas/
/usr/lib/ruby/2.5.0/rdf/redland/schemas/foaf.rb
/usr/lib/ruby/2.5.0/rdf/redland/schemas/owl.rb
/usr/lib/ruby/2.5.0/rdf/redland/schemas/rdfs.rb
/usr/lib/ruby/2.5.0/rdf/redland/serializer.rb
/usr/lib/ruby/2.5.0/rdf/redland/statement.rb
/usr/lib/ruby/2.5.0/rdf/redland/store.rb
/usr/lib/ruby/2.5.0/rdf/redland/stream.rb
/usr/lib/ruby/2.5.0/rdf/redland/uri.rb
/usr/lib/ruby/2.5.0/rdf/redland/util.rb
/usr/lib/ruby/2.5.0/rdf/redland.rb