#include <db_cxx.h> int DbEnv::get_shm_key(long *shm_keyp);
            The DbEnv::get_shm_key() method returns the base segment ID. This is used for Berkeley DB environment
            shared memory regions created in system memory on VxWorks or systems supporting X/Open-style shared memory
            interfaces. It may be specified using the DbEnv::set_shm_key()
            method.
    
         The DbEnv::get_shm_key() method may be called at any time during the
         life of the application.
    
         The DbEnv::get_shm_key() 
            
            
                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.