mirror of https://github.com/python/cpython
72 lines
2.4 KiB
TeX
72 lines
2.4 KiB
TeX
% This section was contributed by Drew Csillag
|
|
% <drew_csillag@geocities.com>, with some re-organization by Fred L.
|
|
% Drake, Jr. <fdrake@acm.org>.
|
|
|
|
\section{Standard Module \module{popen2}}
|
|
\label{module-popen2}
|
|
\stmodindex{popen2}
|
|
|
|
This module allows you to spawn processes and connect their
|
|
input/output/error pipes and obtain their return codes.
|
|
|
|
The primary interface offered by this module is a pair of factory
|
|
functions:
|
|
|
|
\begin{funcdesc}{popen2}{cmd\optional{, bufsize}}
|
|
Executes \var{cmd} as a sub-process. If \var{bufsize} is specified,
|
|
it specifies the buffer size for the I/O pipes. Returns
|
|
\code{(\var{child_stdout}, \var{child_stdin})}.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{popen2}{cmd\optional{, bufsize}}
|
|
Executes \var{cmd} as a sub-process. If \var{bufsize} is specified,
|
|
it specifies the buffer size for the I/O pipes. Returns
|
|
\code{(\var{child_stdout}, \var{child_stdin}, \var{child_stderr})}.
|
|
\end{funcdesc}
|
|
|
|
The class defining the objects returned by the factory functions is
|
|
also available:
|
|
|
|
\begin{classdesc}{Popen3}{cmd\optional{, capturestderr\optional{, bufsize}}}
|
|
This class represents a child process. Normally, \class{Popen3}
|
|
instances are created using the factory functions described above.
|
|
|
|
If not using one off the helper functions to create \class{Popen3}
|
|
objects, the parameter \var{cmd} is the shell command to execute in a
|
|
sub-process. The \var{capturestderr} flag, if true, specifies that
|
|
the object should capture standard error output of the child process.
|
|
The default is false. If the \var{bufsize} parameter is specified, it
|
|
specifies the size of the I/O buffers to/from the child process.
|
|
\end{classdesc}
|
|
|
|
|
|
\subsection{Popen3 Objects}
|
|
\label{popen3-objects}
|
|
|
|
Instances of the \class{Popen3} class have the following methods:
|
|
|
|
\begin{methoddesc}{poll}{}
|
|
Returns \code{-1} if child process hasn't completed yet, or its return
|
|
code otherwise.
|
|
\end{methoddesc}
|
|
|
|
\begin{methoddesc}{wait}{}
|
|
Waits for and returns the return code of the child process.
|
|
\end{methoddesc}
|
|
|
|
|
|
The following attributes of \class{Popen3} objects are also available:
|
|
|
|
\begin{datadesc}{fromchild}
|
|
A file object that provides output from the child process.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{tochild}
|
|
A file object that provides input to the child process.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{childerr}
|
|
Where the standard error from the child process goes is
|
|
\var{capturestderr} was true for the constructor, or \code{None}.
|
|
\end{datadesc}
|