pipes — Interface to shell pipelines (original) (raw)
Source code: Lib/pipes.py
Deprecated since version 3.11, will be removed in version 3.13: The pipes module is deprecated (see PEP 594 for details). Please use the subprocess module instead.
The 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 /bin/sh command lines, a POSIX or compatible shell for os.system() and os.popen() is required.
The pipes module defines the following class:
class pipes.Template¶
An abstraction of a pipeline.
Example:
import pipes t = pipes.Template() t.append('tr a-z A-Z', '--') f = t.open('pipefile', 'w') f.write('hello world') f.close() open('pipefile').read() 'HELLO WORLD'
Template Objects¶
Template objects following methods:
Template.reset()¶
Restore a pipeline template to its initial state.
Template.clone()¶
Return a new, equivalent, pipeline template.
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 givenset -x
command to be more verbose.
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.)
Template.prepend(cmd, kind)¶
Add a new action at the beginning. See append() for explanations of the arguments.
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.
Template.copy(infile, outfile)¶
Copy infile to outfile through the pipe.