pipes — Interface to shell pipelines
Source code: Lib/pipes.py
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:
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.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 -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.
