#include <db_cxx.h>
 
int
Db::fd(int *fdp);

The Db::fd() method provides access to a file descriptor representative of the underlying database. A file descriptor referring to the same file will be returned to all processes that call Db::open() with the same file parameter.

This file descriptor may be safely used as a parameter to the fcntl(2) and flock(2) locking functions.

The Db::fd() method only supports a coarse-grained form of locking. Applications should instead use the Berkeley DB lock manager where possible.

The Db::fd() method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.