New Database Manager

The New Database Manager (NDBM) subroutines maintain key and content pairs in a database. The NDBM subroutines handle large databases and access keyed items in one or two file system accesses.

Keyed items are consecutive characters, taken from a data record, that identify the record and establish its order with respect to other records.

NDBM databases are stored in two files. One file is a directory containing a bit map and it has the extension .dir. The second file contains only data and has the extension .pag.

For example, Network Information Service (NIS) maps maintain database information in NDBM format. NIS maps are created using the makedbm command. The makedbm command converts input into NDBM format files. An NIS map consists of two files: map.key.pag and map.key.dir. The file with the .dir extension serves as an index for the .pag files. The file with the .pag extension contains the key and value pairs.