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Simple ``database'' interface</TITLE>
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<H1><A NAME="SECTION0010500000000000000000">
8.5 <tt class=module>dbm</tt> --
         Simple ``database'' interface</A>
</H1>

<P>
  
<p class=availability>Availability: <span
 class=platform>Unix</span>.</p>

<P>
The <tt class=module>dbm</tt> module provides an interface to the Unix
<tt>(n)dbm</tt> 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
<tt class=method>items()</tt> and <tt class=method>values()</tt> methods are not supported.

<P>
See also the <tt class=module><a href="module-gdbm.html">gdbm</a></tt><a name="l2h-1459"></a> module, which
provides a similar interface using the GNU GDBM library.

<P>
The module defines the following constant and functions:

<P>
<dl><dt><b><a name="l2h-1457"><tt class=exception>error</tt></a></b>
<dd>
Raised on dbm-specific errors, such as I/O errors.
<tt class=exception>KeyError</tt> is raised for general mapping errors like
specifying an incorrect key.
</dl>

<P>
<dl><dt><b><a name="l2h-1458"><tt class=function>open</tt></a></b> (<var>filename, </var><big>[</big><var>flag, </var><big>[</big><var>mode</var><big>]</big><big>]</big>)
<dd>
Open a dbm database and return a dbm object.  The <var>filename</var>
argument is the name of the database file (without the <tt class=file>.dir</tt> or
<tt class=file>.pag</tt> extensions).

<P>
The optional <var>flag</var> argument can be
<tt>'r'</tt> (to open an existing database for reading only -- default),
<tt>'w'</tt> (to open an existing database for reading and writing),
<tt>'c'</tt> (which creates the database if it doesn't exist), or
<tt>'n'</tt> (which always creates a new empty database).

<P>
The optional <var>mode</var> argument is the Unix mode of the file, used
only when the database has to be created.  It defaults to octal
<tt>0666</tt>.
</dl>

<P>
<div class=seealso>
  <p class=heading><b>See Also:</b></p>

  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-anydbm.html">anydbm</a></tt></b>&nbsp;&nbsp;&nbsp;(Generic interface to <tt>dbm</tt>-style databases.)</p>
</div>
  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-whichdb.html">whichdb</a></tt></b>&nbsp;&nbsp;&nbsp;(Utility module used to determine the type of an
                      existing database.)</p>
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