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<H3><A NAME="SECTION008836000000000000000">
6.8.3.6 Replacing popen2.*</A>
</H3>

<P>
<span class="note"><b class="label">Note:</b>
If the cmd argument to popen2 functions is a string, the command
is executed through /bin/sh.  If it is a list, the command is directly
executed.</span>

<P>
<div class="verbatim"><pre>
(child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode)
==&gt;
p = Popen(["somestring"], shell=True, bufsize=bufsize,
          stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdout, child_stdin) = (p.stdout, p.stdin)
</pre></div>

<P>
<div class="verbatim"><pre>
(child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode)
==&gt;
p = Popen(["mycmd", "myarg"], bufsize=bufsize,
          stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdout, child_stdin) = (p.stdout, p.stdin)
</pre></div>

<P>
The popen2.Popen3 and popen3.Popen4 basically works as subprocess.Popen,
except that:

<P>

<UL>
<LI>subprocess.Popen raises an exception if the execution fails

<P>
</LI>
<LI>the <var>capturestderr</var> argument is replaced with the <var>stderr</var>
      argument.

<P>
</LI>
<LI>stdin=PIPE and stdout=PIPE must be specified.

<P>
</LI>
<LI>popen2 closes all file descriptors by default, but you have to
      specify close_fds=True with subprocess.Popen.
</LI>
</UL>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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