Source code: Lib/pipes.py
pipes module defines a class to abstract the concept of a pipeline
— a sequence of converters from one file to another.
Availability: Unix. Not available on VxWorks.
pipes module defines the following class:
- class pipes.Template¶
An abstraction of a pipeline.
>>> 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 following methods:
Restore a pipeline template to its initial state.
Return a new, equivalent, pipeline template.
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 -xcommand 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
'w'may be given.
- Template.copy(infile, outfile)¶
Copy infile to outfile through the pipe.