Compatibility with standard dbm and ndbm . GNU dbm files are not sparse . You can copy them with the UNIX cp command and they will not expand in the copying process. There is a compatibility mode for use with programs that already use UNIX dbm and UNIX ndbm .
GNU dbm has compatibility functions for dbm .
For dbm compatibility functions, you need the include file dbm.h . In this compatibility mode, no gdbm file pointer is required by the user, and Only one file may be opened at a time. All users in compatibility mode are assumed to be writers. If the gdbm file is a read only, it will fail as a writer, but will also try to open it as a reader. All returned pointers in datum structures point to data that gdbm WILL free.