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<H1><A NAME="SECTION0051000000000000000000">
3.10 <tt class="module">linecache</tt> --
Random access to text lines</A>
</H1>
<P>
<P>
The <tt class="module">linecache</tt> module allows one to get any line from any file,
while attempting to optimize internally, using a cache, the common case
where many lines are read from a single file. This is used by the
<tt class='module'><a href="module-traceback.html" tppabs="http://www.python.org/doc/current/lib/module-traceback.html">traceback</a></tt> module to retrieve source lines for inclusion in
the formatted traceback.
<P>
The <tt class="module">linecache</tt> module defines the following functions:
<P>
<dl><dt><b><a name='l2h-400'><tt class='function'>getline</tt></a></b> (<var>filename, lineno</var>)
<dd>
Get line <var>lineno</var> from file named <var>filename</var>. This function
will never throw an exception -- it will return <code>''</code> on errors
(the terminating newline character will be included for lines that are
found).
<P>
If a file named <var>filename</var> is not found, the function will look
for it in the module search path,
<code>sys.path</code>.
</dl>
<P>
<dl><dt><b><a name='l2h-401'><tt class='function'>clearcache</tt></a></b> ()
<dd>
Clear the cache. Use this function if you no longer need lines from
files previously read using <tt class="function">getline()</tt>.
</dl>
<P>
<dl><dt><b><a name='l2h-402'><tt class='function'>checkcache</tt></a></b> ()
<dd>
Check the cache for validity. Use this function if files in the cache
may have changed on disk, and you require the updated version.
</dl>
<P>
Example:
<P>
<dl><dd><pre class="verbatim">
>>> import linecache
>>> linecache.getline('/etc/passwd', 4)
'sys:x:3:3:sys:/dev:/bin/sh\012'
</pre></dl>
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