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| 1 | +% This section was contributed by Drew Csillag |
| 2 | +% <[email protected]>, with some re-organization by Fred L. |
| 3 | + |
| 4 | + |
| 5 | +\section{Standard Module \module{popen2}} |
| 6 | +\label{module-popen2} |
| 7 | +\stmodindex{popen2} |
| 8 | + |
| 9 | +This module allows you to spawn processes and connect their |
| 10 | +input/output/error pipes and obtain their return codes. |
| 11 | + |
| 12 | +The primary interface offered by this module is a pair of factory |
| 13 | +functions: |
| 14 | + |
| 15 | +\begin{funcdesc}{popen2}{cmd\optional{, bufsize}} |
| 16 | +Executes \var{cmd} as a sub-process. If \var{bufsize} is specified, |
| 17 | +it specifies the buffer size for the I/O pipes. Returns |
| 18 | +\code{(\var{child_stdout}, \var{child_stdin})}. |
| 19 | +\end{funcdesc} |
| 20 | + |
| 21 | +\begin{funcdesc}{popen2}{cmd\optional{, bufsize}} |
| 22 | +Executes \var{cmd} as a sub-process. If \var{bufsize} is specified, |
| 23 | +it specifies the buffer size for the I/O pipes. Returns |
| 24 | +\code{(\var{child_stdout}, \var{child_stdin}, \var{child_stderr})}. |
| 25 | +\end{funcdesc} |
| 26 | + |
| 27 | +The class defining the objects returned by the factory functions is |
| 28 | +also available: |
| 29 | + |
| 30 | +\begin{classdesc}{Popen3}{cmd\optional{, capturestderr\optional{, bufsize}}} |
| 31 | +This class represents a child process. Normally, \class{Popen3} |
| 32 | +instances are created using the factory functions described above. |
| 33 | + |
| 34 | +If not using one off the helper functions to create \class{Popen3} |
| 35 | +objects, the parameter \var{cmd} is the shell command to execute in a |
| 36 | +sub-process. The \var{capturestderr} flag, if true, specifies that |
| 37 | +the object should capture standard error output of the child process. |
| 38 | +The default is false. If the \var{bufsize} parameter is specified, it |
| 39 | +specifies the size of the I/O buffers to/from the child process. |
| 40 | +\end{classdesc} |
| 41 | + |
| 42 | + |
| 43 | +\subsection{Popen3 Objects} |
| 44 | +\label{popen3-objects} |
| 45 | + |
| 46 | +Instances of the \class{Popen3} class have the following methods: |
| 47 | + |
| 48 | +\begin{methoddesc}{poll}{} |
| 49 | +Returns \code{-1} if child process hasn't completed yet, or its return |
| 50 | +code otherwise. |
| 51 | +\end{methoddesc} |
| 52 | + |
| 53 | +\begin{methoddesc}{wait}{} |
| 54 | +Waits for and returns the return code of the child process. |
| 55 | +\end{methoddesc} |
| 56 | + |
| 57 | + |
| 58 | +The following attributes of \class{Popen3} objects are also available: |
| 59 | + |
| 60 | +\begin{datadesc}{fromchild} |
| 61 | +A file object that provides output from the child process. |
| 62 | +\end{datadesc} |
| 63 | + |
| 64 | +\begin{datadesc}{tochild} |
| 65 | +A file object that provides input to the child process. |
| 66 | +\end{datadesc} |
| 67 | + |
| 68 | +\begin{datadesc}{childerr} |
| 69 | +Where the standard error from the child process goes is |
| 70 | +\var{capturestderr} was true for the constructor, or \code{None}. |
| 71 | +\end{datadesc} |
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