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<title>6.8.1 Popen3 and Popen4 Objects </title>
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<H2>
<BR>
6.8.1 Popen3 and Popen4 Objects 
</H2>

<P>
Instances of the <tt class="class">Popen3</tt> and <tt class="class">Popen4</tt> classes have the
following methods:

<P>
<dl><dt><b><a name='l2h-1123'><tt class='method'>poll</tt></a></b> ()
<dd>
Returns <code>-1</code> if child process hasn't completed yet, or its return 
code otherwise.
</dl>

<P>
<dl><dt><b><a name='l2h-1124'><tt class='method'>wait</tt></a></b> ()
<dd>
Waits for and returns the return code of the child process.
</dl>

<P>
The following attributes are also available: 

<P>
<dl><dt><b><a name='l2h-1125'><tt class='member'>fromchild</tt></a></b>
<dd>
A file object that provides output from the child process.  For
<tt class="class">Popen4</tt> instances, this will provide both the standard output
and standard error streams.
</dl>

<P>
<dl><dt><b><a name='l2h-1126'><tt class='member'>tochild</tt></a></b>
<dd>
A file object that provides input to the child process.
</dl>

<P>
<dl><dt><b><a name='l2h-1127'><tt class='member'>childerr</tt></a></b>
<dd>
Where the standard error from the child process goes is
<var>capturestderr</var> was true for the constructor, or <code>None</code>.
This will always be <code>None</code> for <tt class="class">Popen4</tt> instances.
</dl>

<P>
<dl><dt><b><a name='l2h-1128'><tt class='member'>pid</tt></a></b>
<dd>
The process ID of the child process.
</dl>

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