Edit File: dbm.txt
:mod:`dbm` --- Simple "database" interface ========================================== .. module:: dbm :platform: Unix :synopsis: The standard "database" interface, based on ndbm. .. note:: The :mod:`dbm` module has been renamed to :mod:`dbm.ndbm` in Python 3.0. The :term:`2to3` tool will automatically adapt imports when converting your sources to 3.0. The :mod:`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 :meth:`items` and :meth:`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 :program:`configure` script will attempt to locate the appropriate header file to simplify building this module. The module defines the following: .. exception:: error Raised on dbm-specific errors, such as I/O errors. :exc:`KeyError` is raised for general mapping errors like specifying an incorrect key. .. data:: library Name of the ``ndbm`` implementation library used. .. function:: 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 :file:`.dir` or :file:`.pag` extensions; note that the BSD DB implementation of the interface will append the extension :file:`.db` and only create one file). The optional *flag* argument must be one of these values: +---------+-------------------------------------------+ | Value | Meaning | +=========+===========================================+ | ``'r'`` | Open existing database for reading only | | | (default) | +---------+-------------------------------------------+ | ``'w'`` | Open existing database for reading and | | | writing | +---------+-------------------------------------------+ | ``'c'`` | Open database for reading and writing, | | | creating it if it doesn't exist | +---------+-------------------------------------------+ | ``'n'`` | Always create a new, empty database, open | | | for reading and writing | +---------+-------------------------------------------+ 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). .. seealso:: Module :mod:`anydbm` Generic interface to ``dbm``\ -style databases. Module :mod:`gdbm` Similar interface to the GNU GDBM library. Module :mod:`whichdb` Utility module used to determine the type of an existing database.
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