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\section{\module{dbm} ---
Simple ``database'' interface}
\declaremodule{builtin}{dbm}
\platform{Unix}
\modulesynopsis{The standard ``database'' interface, based on ndbm.}
The \module{dbm} module provides an interface to the \UNIX{}
\code{(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
\method{items()} and \method{values()} methods are not supported.
See also the \refmodule{gdbm}\refbimodindex{gdbm} module, which
provides a similar interface using the GNU GDBM library.
The module defines the following constant and functions:
\begin{excdesc}{error}
Raised on dbm-specific errors, such as I/O errors.
\exception{KeyError} is raised for general mapping errors like
specifying an incorrect key.
\end{excdesc}
\begin{funcdesc}{open}{filename, \optional{flag, \optional{mode}}}
Open a dbm database and return a dbm object. The \var{filename}
argument is the name of the database file (without the \file{.dir} or
\file{.pag} extensions).
The optional \var{flag} argument can be
\code{'r'} (to open an existing database for reading only --- default),
\code{'w'} (to open an existing database for reading and writing),
\code{'c'} (which creates the database if it doesn't exist), or
\code{'n'} (which always creates a new empty database).
The optional \var{mode} argument is the \UNIX{} mode of the file, used
only when the database has to be created. It defaults to octal
\code{0666}.
\end{funcdesc}
\begin{seealso}
\seemodule{anydbm}{Generic interface to \code{dbm}-style databases.}
\seemodule{whichdb}{Utility module used to determine the type of an
existing database.}
\end{seealso}