Initialize gdbm system. If the file has a size of zero bytes, a file initialization procedure is performed, setting up the initial structure in the file. It is the size of a single transfer from disk to memory. This parameter is ignored if the file has been previously initialized. The minimum size is 512.
Many readers can access the database at the same time.
This option causes gdbm to write the database without any disk file synchronization. This allows faster writes, but may produce an inconsistent database in the event of abnormal termination of the writer. If no errors occur, a pointer to the gdbm file descriptor will be returned. The only parameter of this function is a string. If the value of NULL is provided, gdbm will use a default function.