mirror of https://github.com/python/cpython
75 lines
2.7 KiB
ReStructuredText
75 lines
2.7 KiB
ReStructuredText
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:mod:`dbm` --- Simple "database" interface
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==========================================
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.. module:: dbm
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:platform: Unix
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:synopsis: The standard "database" interface, based on ndbm.
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The :mod:`dbm` module provides an interface to the Unix "(n)dbm" library. Dbm
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objects behave like mappings (dictionaries), except that keys and values are
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always strings. Printing a dbm object doesn't print the keys and values, and the
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:meth:`items` and :meth:`values` methods are not supported.
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This module can be used with the "classic" ndbm interface, the BSD DB
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compatibility interface, or the GNU GDBM compatibility interface. On Unix, the
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:program:`configure` script will attempt to locate the appropriate header file
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to simplify building this module.
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The module defines the following:
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.. exception:: error
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Raised on dbm-specific errors, such as I/O errors. :exc:`KeyError` is raised for
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general mapping errors like specifying an incorrect key.
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.. data:: library
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Name of the ``ndbm`` implementation library used.
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.. function:: open(filename[, flag[, mode]])
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Open a dbm database and return a dbm object. The *filename* argument is the
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name of the database file (without the :file:`.dir` or :file:`.pag` extensions;
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note that the BSD DB implementation of the interface will append the extension
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:file:`.db` and only create one file).
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The optional *flag* argument must be one of these values:
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+---------+-------------------------------------------+
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| Value | Meaning |
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+=========+===========================================+
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| ``'r'`` | Open existing database for reading only |
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| | (default) |
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+---------+-------------------------------------------+
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| ``'w'`` | Open existing database for reading and |
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| | writing |
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+---------+-------------------------------------------+
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| ``'c'`` | Open database for reading and writing, |
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| | creating it if it doesn't exist |
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+---------+-------------------------------------------+
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| ``'n'`` | Always create a new, empty database, open |
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| | for reading and writing |
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+---------+-------------------------------------------+
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The optional *mode* argument is the Unix mode of the file, used only when the
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database has to be created. It defaults to octal ``0666`` (and will be
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modified by the prevailing umask).
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.. seealso::
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Module :mod:`anydbm`
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Generic interface to ``dbm``\ -style databases.
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Module :mod:`gdbm`
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Similar interface to the GNU GDBM library.
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Module :mod:`whichdb`
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Utility module used to determine the type of an existing database.
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