When an error occurs in the Berkeley DB library, a Berkeley DB error or an error
return value is returned by the function. In some cases, however,
the errno value may be insufficient to completely describe
the cause of the error especially during initial application debugging.
The DB->set_errfile function is used to enhance the mechanism for reporting error
messages to the application by setting a C library FILE * to be used for
displaying additional Berkeley DB error messages. In some cases, when an error
occurs, Berkeley DB will output an additional error message to the specified
The error message will consist of the prefix string and a colon
(":") (if a prefix string was previously specified using
DB->set_errpfx or DBENV->set_errpfx), an error string, and
a trailing <newline> character.
This error logging enhancement does not slow performance or significantly
increase application size, and may be run during normal operation as well
as during application debugging.
For DB handles opened inside of Berkeley DB environments, calling the
DB->set_errfile function affects the entire environment and is equivalent to calling
the DBENV->set_errfile function.
The DB->set_errfile interface may be used to configure Berkeley DB at any time
during the life of the application.