The DBM functions use a common interface to the range of DBM functions. Most systems come with some sort of DBM support; the support provided on your system can be found in phpinfo() or by using the dblist() function. In most cases, you'll have GDBM, although other implementations include NDBM, Berkeley DB, and so on. You can explicitly tell PHP which version to use when compiling PHP. There is no error reporting if these functions return an error, so some care should be taken when using these functions. Additionally, values in DBM databases are strictly zero-terminated strings and cannot contain octet values of zero. These functions are deprecated in favor of the DBA (database abstraction) functions.
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing (Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). The authors of this book have elected not to choose any options under the OPL. This online book was obtained from http://www.fooassociates.com/phpfer/ and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4 for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All persons and entities shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from the information contained in this book.