/Doc/library/pipes.rst
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- :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.