The database file must be a text file, one line per database record, with the key the first field on the line.
Any previous index is silently overwritten.
The input is in the form of database lines, although only the keys are significant. With -c , dbz checks the database for internal consistency. Normally, dbz checks whether a key is already in the database before adding it. The -u option suppresses this check, speeding things up at the expense of safety. A new index is normally created with default size, case mapping, and tagging.