/usr/ is in libhealpix-cxx-dev 3.30.0-8ubuntu1.
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..
/usr/include/
/usr/include/healpix_cxx/
/usr/include/healpix_cxx/alloc_utils.h
/usr/include/healpix_cxx/alm.h
/usr/include/healpix_cxx/alm_fitsio.h
/usr/include/healpix_cxx/alm_healpix_tools.h
/usr/include/healpix_cxx/alm_powspec_tools.h
/usr/include/healpix_cxx/arr.h
/usr/include/healpix_cxx/datatypes.h
/usr/include/healpix_cxx/error_handling.h
/usr/include/healpix_cxx/fitshandle.h
/usr/include/healpix_cxx/healpix_base.h
/usr/include/healpix_cxx/healpix_data_io.h
/usr/include/healpix_cxx/healpix_map.h
/usr/include/healpix_cxx/healpix_map_fitsio.h
/usr/include/healpix_cxx/healpix_tables.h
/usr/include/healpix_cxx/lsconstants.h
/usr/include/healpix_cxx/math_utils.h
/usr/include/healpix_cxx/moc.h
/usr/include/healpix_cxx/moc_fitsio.h
/usr/include/healpix_cxx/moc_query.h
/usr/include/healpix_cxx/pointing.h
/usr/include/healpix_cxx/powspec.h
/usr/include/healpix_cxx/powspec_fitsio.h
/usr/include/healpix_cxx/rangeset.h
/usr/include/healpix_cxx/rotmatrix.h
/usr/include/healpix_cxx/safe_cast.h
/usr/include/healpix_cxx/sharp.h
/usr/include/healpix_cxx/sharp_geomhelpers.c
/usr/include/healpix_cxx/sharp_geomhelpers.h
/usr/include/healpix_cxx/sharp_lowlevel.h
/usr/include/healpix_cxx/sse_utils_cxx.h
/usr/include/healpix_cxx/string_utils.h
/usr/include/healpix_cxx/vec3.h
/usr/include/healpix_cxx/wigner.h
/usr/include/healpix_cxx/xcomplex.h
/usr/lib/
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/libhealpix_cxx.a
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/healpix_cxx.pc
/usr/share/
/usr/share/doc/
/usr/share/doc/libhealpix-cxx-dev/
/usr/share/doc/libhealpix-cxx-dev/README.Debian
/usr/share/doc/libhealpix-cxx-dev/copyright
/usr/lib/x86_64-linux-gnu/libhealpix_cxx.so
/usr/share/doc/libhealpix-cxx-dev/changelog.Debian.gz