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