#include <db.h>

void
DB->set_msgcall(DB *, void (*db_msgcall_fcn)(const DB_ENV *dbenv,
                                             const char *msgpfx,
                                             const char *msg));  

There are interfaces in the Berkeley DB library which either directly output informational messages or statistical information, or configure the library to output such messages when performing other operations, for example, DB_ENV->set_verbose() and DB_ENV->stat_print() .

The DB_ENV->set_msgcall() and DB->set_msgcall() methods are used to pass these messages to the application, and Berkeley DB will call db_msgcall_fcn with each message. It is up to the db_msgcall_fcn function to display the message in an appropriate manner.

Setting db_msgcall_fcn to NULL unconfigures the callback interface.

Alternatively, you can use the DB->set_msgfile() or DB->set_msgfile() methods to display the messages via a C library FILE *.

For DB handles opened inside of Berkeley DB environments, calling the DB->set_msgcall() method affects the entire environment and is equivalent to calling the DB_ENV->set_msgcall() method.

The DB->set_msgcall() method configures operations performed using the specified DB handle, not all operations performed on the underlying database.

The DB->set_msgcall() method may be called at any time during the life of the application.