Export /Expdp without data

expdp:

expdp username/password DIRECTORY=directory_object_name \
                        DUMPFILE=dumpfile_name \
                        TABLES=table_names|TABLESPACES=tablespace_names|FULL=y \
                        CONTENT=metadata_only

exp:

exp username/password GRANTS=y \
                      CONSTRAINTS=y \
                      ROWS=n