``--config=FILE``
Specify the configuration file to use. This overrides any
- configuration file specified by ${NOTMUCH\_CONFIG}.
+ configuration file specified by ${NOTMUCH\_CONFIG}. The empty
+ string is a permitted and sometimes useful value of *FILE*, which
+ tells ``notmuch`` to use only configuration metadata from the database.
``--uuid=HEX``
Enforce that the database UUID (a unique identifier which persists