11.8. dbm — Simple “database” interface

注解

The dbm module has been renamed to dbm.ndbm in Python 3. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.

The dbm module provides an interface to the Unix “(n)dbm” library. Dbm objects behave like mappings (dictionaries), except that keys and values are always strings. Printing a dbm object doesn’t print the keys and values, and the items() and values() methods are not supported.

This module can be used with the “classic” ndbm interface, the BSD DB compatibility interface, or the GNU GDBM compatibility interface. On Unix, the configure script will attempt to locate the appropriate header file to simplify building this module.

该模块定义以下内容：

exception dbm.error

Raised on dbm-specific errors, such as I/O errors. KeyError is raised for general mapping errors like specifying an incorrect key.

dbm.library

所使用的 ndbm 实现库的名称。

dbm.open(filename[, flag[, mode]])

Open a dbm database and return a dbm object. The filename argument is the name of the database file (without the .dir or .pag extensions; note that the BSD DB implementation of the interface will append the extension .db and only create one file).

可选的 flag 参数必须是下列值之一：

值	含义
'r'	以只读方式打开现有数据库（默认）
'w'	以读写方式打开现有数据库
'c'	以读写方式打开数据库，如果不存在则创建它
'n'	始终创建一个新的空数据库，以读写方式打开

The optional mode argument is the Unix mode of the file, used only when the database has to be created. It defaults to octal 0666 (and will be modified by the prevailing umask).

In addition to the dictionary-like methods, dbm objects provide the following method:

dbm.close()

Close the dbm database.

参见

Module anydbm

Generic interface to dbm-style databases.

Module gdbm

Similar interface to the GNU GDBM library.

Module whichdb

Utility module used to determine the type of an existing database.