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v0.5.1
v0.5.1
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Tip revision: 74f4bd53e03ded8408bcc2de67cf0f5a4ac5b1a1 authored by Barry Warsaw on 23 February 2012, 15:59:38 UTC
Bump some more copyright years (as per PEP 101), since this is the first
Bump some more copyright years (as per PEP 101), since this is the first
Tip revision: 74f4bd5
pipes.rst
:mod:`pipes` --- Interface to shell pipelines
=============================================
.. module:: pipes
:platform: Unix
:synopsis: A Python interface to Unix shell pipelines.
.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
The :mod:`pipes` module defines a class to abstract the concept of a *pipeline*
--- a sequence of converters from one file to another.
Because the module uses :program:`/bin/sh` command lines, a POSIX or compatible
shell for :func:`os.system` and :func:`os.popen` is required.
The :mod:`pipes` module defines the following class:
.. class:: Template()
An abstraction of a pipeline.
Example::
>>> 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'
.. _template-objects:
Template Objects
----------------
Template objects following methods:
.. method:: Template.reset()
Restore a pipeline template to its initial state.
.. method:: Template.clone()
Return a new, equivalent, pipeline template.
.. method:: Template.debug(flag)
If *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
``set -x`` command to be more verbose.
.. method:: Template.append(cmd, kind)
Append a new action at the end. The *cmd* variable must be a valid bourne shell
command. The *kind* variable consists of two letters.
The first letter can be either of ``'-'`` (which means the command reads its
standard input), ``'f'`` (which means the commands reads a given file on the
command line) or ``'.'`` (which means the commands reads no input, and hence
must be first.)
Similarly, the second letter can be either of ``'-'`` (which means the command
writes to standard output), ``'f'`` (which means the command writes a file on
the command line) or ``'.'`` (which means the command does not write anything,
and hence must be last.)
.. method:: Template.prepend(cmd, kind)
Add a new action at the beginning. See :meth:`append` for explanations of the
arguments.
.. method:: Template.open(file, mode)
Return a file-like object, open to *file*, but read from or written to by the
pipeline. Note that only one of ``'r'``, ``'w'`` may be given.
.. method:: Template.copy(infile, outfile)
Copy *infile* to *outfile* through the pipe.