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85 lines
2.6 KiB
TeX
85 lines
2.6 KiB
TeX
\section{\module{pipes} ---
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Interface to shell pipelines}
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\declaremodule{standard}{pipes}
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\platform{Unix}
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\sectionauthor{Moshe Zadka}{moshez@zadka.site.co.il}
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\modulesynopsis{A Python interface to \UNIX\ shell pipelines.}
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The \module{pipes} module defines a class to abstract the concept of
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a \emph{pipeline} --- a sequence of convertors from one file to
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another.
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Because the module uses \program{/bin/sh} command lines, a \POSIX{} or
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compatible shell for \function{os.system()} and \function{os.popen()}
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is required.
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The \module{pipes} module defines the following class:
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\begin{classdesc}{Template}{}
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An abstraction of a pipeline.
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\end{classdesc}
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Example:
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\begin{verbatim}
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>>> import pipes
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>>> t=pipes.Template()
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>>> t.append('tr a-z A-Z', '--')
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>>> f=t.open('/tmp/1', 'w')
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>>> f.write('hello world')
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>>> f.close()
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>>> open('/tmp/1').read()
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'HELLO WORLD'
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\end{verbatim}
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\subsection{Template Objects \label{template-objects}}
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Template objects following methods:
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\begin{methoddesc}{reset}{}
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Restore a pipeline template to its initial state.
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\end{methoddesc}
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\begin{methoddesc}{clone}{}
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Return a new, equivalent, pipeline template.
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\end{methoddesc}
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\begin{methoddesc}{debug}{flag}
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If \var{flag} is true, turn debugging on. Otherwise, turn debugging
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off. When debugging is on, commands to be executed are printed, and
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the shell is given \code{set -x} command to be more verbose.
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\end{methoddesc}
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\begin{methoddesc}{append}{cmd, kind}
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Append a new action at the end. The \var{cmd} variable must be a valid
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bourne shell command. The \var{kind} variable consists of two letters.
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The first letter can be either of \code{'-'} (which means the command
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reads its standard input), \code{'f'} (which means the commands reads
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a given file on the command line) or \code{'.'} (which means the commands
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reads no input, and hence must be first.)
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Similarly, the second letter can be either of \code{'-'} (which means
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the command writes to standard output), \code{'f'} (which means the
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command writes a file on the command line) or \code{'.'} (which means
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the command does not write anything, and hence must be last.)
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\end{methoddesc}
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\begin{methoddesc}{prepend}{cmd, kind}
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Add a new action at the beginning. See \method{append()} for explanations
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of the arguments.
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\end{methoddesc}
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\begin{methoddesc}{open}{file, mode}
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Return a file-like object, open to \var{file}, but read from or
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written to by the pipeline. Note that only one of \code{'r'},
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\code{'w'} may be given.
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\end{methoddesc}
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\begin{methoddesc}{copy}{infile, outfile}
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Copy \var{infile} to \var{outfile} through the pipe.
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\end{methoddesc}
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