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<ul>
<li><a class="reference internal" href="#">tempfile – Create temporary filesystem resources.</a><ul>
<li><a class="reference internal" href="#temporaryfile">TemporaryFile</a></li>
<li><a class="reference internal" href="#namedtemporaryfile">NamedTemporaryFile</a></li>
<li><a class="reference internal" href="#mkdtemp">mkdtemp</a></li>
<li><a class="reference internal" href="#predicting-names">Predicting Names</a></li>
<li><a class="reference internal" href="#temporary-file-location">Temporary File Location</a></li>
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<div class="section" id="module-tempfile">
<span id="tempfile-create-temporary-filesystem-resources"></span><h1>tempfile – Create temporary filesystem resources.<a class="headerlink" href="#module-tempfile" title="Permalink to this headline">¶</a></h1>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Purpose:</th><td class="field-body">Create temporary filesystem resources.</td>
</tr>
<tr class="field"><th class="field-name">Python Version:</th><td class="field-body">Since 1.4 with major security revisions in 2.3</td>
</tr>
</tbody>
</table>
<p>Many programs need to create files to write intermediate
data. Creating files with unique names securely, so they cannot be
guessed by someone wanting to break the application, is
challenging. The <a class="reference internal" href="#module-tempfile" title="tempfile: Create temporary filesystem resources."><tt class="xref py py-mod docutils literal"><span class="pre">tempfile</span></tt></a> module provides several functions for
creating filesystem resources securely. <tt class="xref py py-func docutils literal"><span class="pre">TemporaryFile()</span></tt> opens
and returns an un-named file, <tt class="xref py py-func docutils literal"><span class="pre">NamedTemporaryFile()</span></tt> opens and
returns a named file, and <tt class="xref py py-func docutils literal"><span class="pre">mkdtemp()</span></tt> creates a temporary
directory and returns its name.</p>
<div class="section" id="temporaryfile">
<h2>TemporaryFile<a class="headerlink" href="#temporaryfile" title="Permalink to this headline">¶</a></h2>
<p>If your application needs a temporary file to store data, but does not
need to share that file with other programs, the best option for
creating the file is the <tt class="xref py py-func docutils literal"><span class="pre">TemporaryFile()</span></tt> function. It creates
a file, and on platforms where it is possible, unlinks it
immediately. This makes it impossible for another program to find or
open the file, since there is no reference to it in the filesystem
table. The file created by <tt class="xref py py-func docutils literal"><span class="pre">TemporaryFile()</span></tt> is removed
automatically when it is closed.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">tempfile</span>
<span class="k">print</span> <span class="s">'Building a file name yourself:'</span>
<span class="n">filename</span> <span class="o">=</span> <span class="s">'/tmp/guess_my_name.</span><span class="si">%s</span><span class="s">.txt'</span> <span class="o">%</span> <span class="n">os</span><span class="o">.</span><span class="n">getpid</span><span class="p">()</span>
<span class="n">temp</span> <span class="o">=</span> <span class="nb">open</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="s">'w+b'</span><span class="p">)</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">print</span> <span class="s">'temp:'</span><span class="p">,</span> <span class="n">temp</span>
<span class="k">print</span> <span class="s">'temp.name:'</span><span class="p">,</span> <span class="n">temp</span><span class="o">.</span><span class="n">name</span>
<span class="k">finally</span><span class="p">:</span>
<span class="n">temp</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
<span class="c"># Clean up the temporary file yourself</span>
<span class="n">os</span><span class="o">.</span><span class="n">remove</span><span class="p">(</span><span class="n">filename</span><span class="p">)</span>
<span class="k">print</span>
<span class="k">print</span> <span class="s">'TemporaryFile:'</span>
<span class="n">temp</span> <span class="o">=</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">TemporaryFile</span><span class="p">()</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">print</span> <span class="s">'temp:'</span><span class="p">,</span> <span class="n">temp</span>
<span class="k">print</span> <span class="s">'temp.name:'</span><span class="p">,</span> <span class="n">temp</span><span class="o">.</span><span class="n">name</span>
<span class="k">finally</span><span class="p">:</span>
<span class="c"># Automatically cleans up the file</span>
<span class="n">temp</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
</pre></div>
</div>
<p>This example illustrates the difference in creating a temporary file
using a common pattern for making up a name, versus using the
<tt class="xref py py-func docutils literal"><span class="pre">TemporaryFile()</span></tt> function. Notice that the file returned by
<tt class="xref py py-func docutils literal"><span class="pre">TemporaryFile()</span></tt> has no name.</p>
<div class="highlight-python"><pre>$ python tempfile_TemporaryFile.py
Building a file name yourself:
temp: <open file '/tmp/guess_my_name.14932.txt', mode 'w+b' at 0x1004481e0>
temp.name: /tmp/guess_my_name.14932.txt
TemporaryFile:
temp: <open file '<fdopen>', mode 'w+b' at 0x1004486f0>
temp.name: <fdopen></pre>
</div>
<p>By default, the file handle is created with mode <tt class="docutils literal"><span class="pre">'w+b'</span></tt> so it
behaves consistently on all platforms and your program can write to it
and read from it.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">tempfile</span>
<span class="n">temp</span> <span class="o">=</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">TemporaryFile</span><span class="p">()</span>
<span class="k">try</span><span class="p">:</span>
<span class="n">temp</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="s">'Some data'</span><span class="p">)</span>
<span class="n">temp</span><span class="o">.</span><span class="n">seek</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span>
<span class="k">print</span> <span class="n">temp</span><span class="o">.</span><span class="n">read</span><span class="p">()</span>
<span class="k">finally</span><span class="p">:</span>
<span class="n">temp</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
</pre></div>
</div>
<p>After writing, you have to rewind the file handle using <tt class="xref py py-func docutils literal"><span class="pre">seek()</span></tt>
in order to read the data back from it.</p>
<div class="highlight-python"><pre>$ python tempfile_TemporaryFile_binary.py
Some data</pre>
</div>
<p>If you want the file to work in text mode, set <em>mode</em> to <tt class="docutils literal"><span class="pre">'w+t'</span></tt>
when you create it:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">tempfile</span>
<span class="n">f</span> <span class="o">=</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">TemporaryFile</span><span class="p">(</span><span class="n">mode</span><span class="o">=</span><span class="s">'w+t'</span><span class="p">)</span>
<span class="k">try</span><span class="p">:</span>
<span class="n">f</span><span class="o">.</span><span class="n">writelines</span><span class="p">([</span><span class="s">'first</span><span class="se">\n</span><span class="s">'</span><span class="p">,</span> <span class="s">'second</span><span class="se">\n</span><span class="s">'</span><span class="p">])</span>
<span class="n">f</span><span class="o">.</span><span class="n">seek</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span>
<span class="k">for</span> <span class="n">line</span> <span class="ow">in</span> <span class="n">f</span><span class="p">:</span>
<span class="k">print</span> <span class="n">line</span><span class="o">.</span><span class="n">rstrip</span><span class="p">()</span>
<span class="k">finally</span><span class="p">:</span>
<span class="n">f</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
</pre></div>
</div>
<p>The file handle treats the data as text:</p>
<div class="highlight-python"><pre>$ python tempfile_TemporaryFile_text.py
first
second</pre>
</div>
</div>
<div class="section" id="namedtemporaryfile">
<h2>NamedTemporaryFile<a class="headerlink" href="#namedtemporaryfile" title="Permalink to this headline">¶</a></h2>
<p>There are situations, however, where having a named temporary file is
important. If your application spans multiple processes, or even
hosts, naming the file is the simplest way to pass it between parts of
the application. The <tt class="xref py py-func docutils literal"><span class="pre">NamedTemporaryFile()</span></tt> function creates a
file with a name, accessed from the name attribute.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">tempfile</span>
<span class="n">temp</span> <span class="o">=</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">NamedTemporaryFile</span><span class="p">()</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">print</span> <span class="s">'temp:'</span><span class="p">,</span> <span class="n">temp</span>
<span class="k">print</span> <span class="s">'temp.name:'</span><span class="p">,</span> <span class="n">temp</span><span class="o">.</span><span class="n">name</span>
<span class="k">finally</span><span class="p">:</span>
<span class="c"># Automatically cleans up the file</span>
<span class="n">temp</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
<span class="k">print</span> <span class="s">'Exists after close:'</span><span class="p">,</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">exists</span><span class="p">(</span><span class="n">temp</span><span class="o">.</span><span class="n">name</span><span class="p">)</span>
</pre></div>
</div>
<p>Even though the file is named, it is still removed after the handle is
closed.</p>
<div class="highlight-python"><pre>$ python tempfile_NamedTemporaryFile.py
temp: <open file '<fdopen>', mode 'w+b' at 0x1004481e0>
temp.name: /var/folders/9R/9R1t+tR02Raxzk+F71Q50U+++Uw/-Tmp-/tmp0zHZvX
Exists after close: False</pre>
</div>
</div>
<div class="section" id="mkdtemp">
<h2>mkdtemp<a class="headerlink" href="#mkdtemp" title="Permalink to this headline">¶</a></h2>
<p>If you need several temporary files, it may be more convenient to
create a single temporary directory and then open all of the files in
that directory. To create a temporary directory, use
<tt class="xref py py-func docutils literal"><span class="pre">mkdtemp()</span></tt>.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">tempfile</span>
<span class="n">directory_name</span> <span class="o">=</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">mkdtemp</span><span class="p">()</span>
<span class="k">print</span> <span class="n">directory_name</span>
<span class="c"># Clean up the directory yourself</span>
<span class="n">os</span><span class="o">.</span><span class="n">removedirs</span><span class="p">(</span><span class="n">directory_name</span><span class="p">)</span>
</pre></div>
</div>
<p>Since the directory is not “opened” per se, you have to remove it
yourself when you are done with it.</p>
<div class="highlight-python"><pre>$ python tempfile_mkdtemp.py
/var/folders/9R/9R1t+tR02Raxzk+F71Q50U+++Uw/-Tmp-/tmpB1CR8M</pre>
</div>
</div>
<div class="section" id="predicting-names">
<h2>Predicting Names<a class="headerlink" href="#predicting-names" title="Permalink to this headline">¶</a></h2>
<p>For debugging purposes, it is useful to be able to include some
indication of the origin of the temporary files. While obviously less
secure than strictly anonymous temporary files, including a
predictable portion in the name lets you find the file to examine it
while your program is using it. All of the functions described so far
take three arguments to allow you to control the filenames to some
degree. Names are generated using the formula:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="nb">dir</span> <span class="o">+</span> <span class="n">prefix</span> <span class="o">+</span> <span class="n">random</span> <span class="o">+</span> <span class="n">suffix</span>
</pre></div>
</div>
<p>where all of the values except random can be passed as arguments to
<tt class="xref py py-func docutils literal"><span class="pre">TemporaryFile()</span></tt>, <tt class="xref py py-func docutils literal"><span class="pre">NamedTemporaryFile()</span></tt>, and
<tt class="xref py py-func docutils literal"><span class="pre">mkdtemp()</span></tt>. For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">tempfile</span>
<span class="n">temp</span> <span class="o">=</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">NamedTemporaryFile</span><span class="p">(</span><span class="n">suffix</span><span class="o">=</span><span class="s">'_suffix'</span><span class="p">,</span>
<span class="n">prefix</span><span class="o">=</span><span class="s">'prefix_'</span><span class="p">,</span>
<span class="nb">dir</span><span class="o">=</span><span class="s">'/tmp'</span><span class="p">,</span>
<span class="p">)</span>
<span class="k">try</span><span class="p">:</span>
<span class="k">print</span> <span class="s">'temp:'</span><span class="p">,</span> <span class="n">temp</span>
<span class="k">print</span> <span class="s">'temp.name:'</span><span class="p">,</span> <span class="n">temp</span><span class="o">.</span><span class="n">name</span>
<span class="k">finally</span><span class="p">:</span>
<span class="n">temp</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
</pre></div>
</div>
<p>The <em>prefix</em> and <em>suffix</em> arguments are combined with a random string
of characters to build the file name, and the <em>dir</em> argument is taken
as-is and used as the location of the new file.</p>
<div class="highlight-python"><pre>$ python tempfile_NamedTemporaryFile_args.py
temp: <open file '<fdopen>', mode 'w+b' at 0x1004481e0>
temp.name: /tmp/prefix_UyCzjc_suffix</pre>
</div>
</div>
<div class="section" id="temporary-file-location">
<h2>Temporary File Location<a class="headerlink" href="#temporary-file-location" title="Permalink to this headline">¶</a></h2>
<p>If you don’t specify an explicit destination using the <em>dir</em> argument,
the actual path used for the temporary files will vary based on your
platform and settings. The tempfile module includes two functions for
querying the settings being used at runtime:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">tempfile</span>
<span class="k">print</span> <span class="s">'gettempdir():'</span><span class="p">,</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">gettempdir</span><span class="p">()</span>
<span class="k">print</span> <span class="s">'gettempprefix():'</span><span class="p">,</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">gettempprefix</span><span class="p">()</span>
</pre></div>
</div>
<p><tt class="xref py py-func docutils literal"><span class="pre">gettempdir()</span></tt> returns the default directory that will hold all
of the temporary files and <tt class="xref py py-func docutils literal"><span class="pre">gettempprefix()</span></tt> returns the string
prefix for new file and directory names.</p>
<div class="highlight-python"><pre>$ python tempfile_settings.py
gettempdir(): /var/folders/9R/9R1t+tR02Raxzk+F71Q50U+++Uw/-Tmp-
gettempprefix(): tmp</pre>
</div>
<p>The value returned by <tt class="xref py py-func docutils literal"><span class="pre">gettempdir()</span></tt> is set based on a
straightforward algorithm of looking through a list of locations for
the first place the current process can create a file. From the
library documentation:</p>
<p>Python searches a standard list of directories and sets tempdir to the
first one which the calling user can create files in. The list is:</p>
<ol class="arabic simple">
<li>The directory named by the <tt class="docutils literal"><span class="pre">TMPDIR</span></tt> environment variable.</li>
<li>The directory named by the <tt class="docutils literal"><span class="pre">TEMP</span></tt> environment variable.</li>
<li>The directory named by the <tt class="docutils literal"><span class="pre">TMP</span></tt> environment variable.</li>
<li>A platform-specific location:<ul>
<li>On RiscOS, the directory named by the <tt class="docutils literal"><span class="pre">Wimp$ScrapDir</span></tt> environment
variable.</li>
<li>On Windows, the directories <tt class="docutils literal"><span class="pre">C:\TEMP</span></tt>, <tt class="docutils literal"><span class="pre">C:\TMP</span></tt>, <tt class="docutils literal"><span class="pre">\TEMP</span></tt>,
and <tt class="docutils literal"><span class="pre">\TMP</span></tt>, in that order.</li>
<li>On all other platforms, the directories <tt class="docutils literal"><span class="pre">/tmp</span></tt>, <tt class="docutils literal"><span class="pre">/var/tmp</span></tt>,
and <tt class="docutils literal"><span class="pre">/usr/tmp</span></tt>, in that order.</li>
</ul>
</li>
<li>As a last resort, the current working directory.</li>
</ol>
<p>If your program needs to use a global location for all temporary files
that you need to set explicitly but do not want to set through one of
these environment variables, you can set <tt class="docutils literal"><span class="pre">tempfile.tempdir</span></tt>
directly.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">tempfile</span>
<span class="n">tempfile</span><span class="o">.</span><span class="n">tempdir</span> <span class="o">=</span> <span class="s">'/I/changed/this/path'</span>
<span class="k">print</span> <span class="s">'gettempdir():'</span><span class="p">,</span> <span class="n">tempfile</span><span class="o">.</span><span class="n">gettempdir</span><span class="p">()</span>
</pre></div>
</div>
<div class="highlight-python"><pre>$ python tempfile_tempdir.py
gettempdir(): /I/changed/this/path</pre>
</div>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<dl class="last docutils">
<dt><a class="reference external" href="http://docs.python.org/lib/module-tempfile.html">tempfile</a></dt>
<dd>Standard library documentation for this module.</dd>
<dt><a class="reference internal" href="../articles/file_access.html#article-file-access"><em>File Access</em></a></dt>
<dd>More modules for working with files.</dd>
</dl>
</div>
</div>
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