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