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<H1><A NAME="SECTION0052400000000000000000">
3.24 <tt class="module">user</tt> --
User-specific configuration hook</A>
</H1>
<P>
<P>
<P>
As a policy, Python doesn't run user-specified code on startup of
Python programs. (Only interactive sessions execute the script
specified in the <a class="envvar" name='l2h-536'>$PYTHONSTARTUP</a> environment variable if it
exists).
<P>
However, some programs or sites may find it convenient to allow users
to have a standard customization file, which gets run when a program
requests it. This module implements such a mechanism. A program
that wishes to use the mechanism must execute the statement
<P>
<dl><dd><pre class="verbatim">
import user
</pre></dl>
<P>
The <tt class="module">user</tt> module looks for a file <span class="file">.pythonrc.py</span> in the user's
home directory and if it can be opened, executes it (using
<tt class="function">execfile()</tt>) in its own (i.e. the
module <tt class="module">user</tt>'s) global namespace. Errors during this phase
are not caught; that's up to the program that imports the
<tt class="module">user</tt> module, if it wishes. The home directory is assumed to
be named by the <a class="envvar" name='l2h-538'>$HOME</a> environment variable; if this is not set,
the current directory is used.
<P>
The user's <span class="file">.pythonrc.py</span> could conceivably test for
<code>sys.version</code> if it wishes to do different things depending on
the Python version.
<P>
A warning to users: be very conservative in what you place in your
<span class="file">.pythonrc.py</span> file. Since you don't know which programs will
use it, changing the behavior of standard modules or functions is
generally not a good idea.
<P>
A suggestion for programmers who wish to use this mechanism: a simple
way to let users specify options for your package is to have them
define variables in their <span class="file">.pythonrc.py</span> file that you test in
your module. For example, a module <tt class="module">spam</tt> that has a verbosity
level can look for a variable <code>user.spam_verbose</code>, as follows:
<P>
<dl><dd><pre class="verbatim">
import user
try:
verbose = user.spam_verbose # user's verbosity preference
except AttributeError:
verbose = 0 # default verbosity
</pre></dl>
<P>
Programs with extensive customization needs are better off reading a
program-specific customization file.
<P>
Programs with security or privacy concerns should <i>not</i> import
this module; a user can easily break into a program by placing
arbitrary code in the <span class="file">.pythonrc.py</span> file.
<P>
Modules for general use should <i>not</i> import this module; it may
interfere with the operation of the importing program.
<P>
<div class='seealso'>
<p class='heading'><b>See Also:</b></p>
<dl compact class="seemodule">
<dt>Module <b><tt class='module'><a href="module-site.html" tppabs="http://www.python.org/doc/current/lib/module-site.html">site</a></tt>:</b>
<dd>site-wide customization mechanism.
</dl>
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