/usr/include/dune/grid/io/ is in libdune-grid-dev 2.5.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/dune/grid/io/file/
/usr/include/dune/grid/io/file/amiramesh/
/usr/include/dune/grid/io/file/amiramesh/amirameshreader.cc
/usr/include/dune/grid/io/file/amiramesh/amirameshwriter.cc
/usr/include/dune/grid/io/file/amiramesh/psurfaceboundary.hh
/usr/include/dune/grid/io/file/amirameshreader.hh
/usr/include/dune/grid/io/file/amirameshwriter.hh
/usr/include/dune/grid/io/file/dgfparser/
/usr/include/dune/grid/io/file/dgfparser.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/
/usr/include/dune/grid/io/file/dgfparser/blocks/basic.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/boundarydom.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/boundaryseg.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/cube.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/dim.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/general.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/gridparameter.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/interval.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/periodicfacetrans.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/projection.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/simplex.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/simplexgeneration.hh
/usr/include/dune/grid/io/file/dgfparser/blocks/vertex.hh
/usr/include/dune/grid/io/file/dgfparser/dgfexception.hh
/usr/include/dune/grid/io/file/dgfparser/dgfgeogrid.hh
/usr/include/dune/grid/io/file/dgfparser/dgfgridfactory.hh
/usr/include/dune/grid/io/file/dgfparser/dgfidentitygrid.hh
/usr/include/dune/grid/io/file/dgfparser/dgfoned.hh
/usr/include/dune/grid/io/file/dgfparser/dgfparser.hh
/usr/include/dune/grid/io/file/dgfparser/dgfug.hh
/usr/include/dune/grid/io/file/dgfparser/dgfwriter.hh
/usr/include/dune/grid/io/file/dgfparser/dgfyasp.hh
/usr/include/dune/grid/io/file/dgfparser/entitykey.hh
/usr/include/dune/grid/io/file/dgfparser/entitykey_inline.hh
/usr/include/dune/grid/io/file/dgfparser/gridptr.hh
/usr/include/dune/grid/io/file/dgfparser/macrogrid.hh
/usr/include/dune/grid/io/file/dgfparser/parser.hh
/usr/include/dune/grid/io/file/gmshreader.hh
/usr/include/dune/grid/io/file/gmshwriter.hh
/usr/include/dune/grid/io/file/gnuplot/
/usr/include/dune/grid/io/file/gnuplot.hh
/usr/include/dune/grid/io/file/gnuplot/gnuplot.cc
/usr/include/dune/grid/io/file/printgrid.hh
/usr/include/dune/grid/io/file/starcdreader.hh
/usr/include/dune/grid/io/file/vtk/
/usr/include/dune/grid/io/file/vtk.hh
/usr/include/dune/grid/io/file/vtk/b64enc.hh
/usr/include/dune/grid/io/file/vtk/basicwriter.hh
/usr/include/dune/grid/io/file/vtk/boundaryiterators.hh
/usr/include/dune/grid/io/file/vtk/boundarywriter.hh
/usr/include/dune/grid/io/file/vtk/common.hh
/usr/include/dune/grid/io/file/vtk/corner.hh
/usr/include/dune/grid/io/file/vtk/corneriterator.hh
/usr/include/dune/grid/io/file/vtk/dataarraywriter.hh
/usr/include/dune/grid/io/file/vtk/function.hh
/usr/include/dune/grid/io/file/vtk/functionwriter.hh
/usr/include/dune/grid/io/file/vtk/pointiterator.hh
/usr/include/dune/grid/io/file/vtk/pvtuwriter.hh
/usr/include/dune/grid/io/file/vtk/skeletonfunction.hh
/usr/include/dune/grid/io/file/vtk/streams.hh
/usr/include/dune/grid/io/file/vtk/subsamplingvtkwriter.hh
/usr/include/dune/grid/io/file/vtk/volumeiterators.hh
/usr/include/dune/grid/io/file/vtk/volumewriter.hh
/usr/include/dune/grid/io/file/vtk/vtksequencewriter.hh
/usr/include/dune/grid/io/file/vtk/vtksequencewriterbase.hh
/usr/include/dune/grid/io/file/vtk/vtkwriter.hh
/usr/include/dune/grid/io/file/vtk/vtuwriter.hh