pipes
— Shell 管道接口
¶
源代码： Lib/pipes.py
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.
pipes
模块定义了下列类：
pipes.
Template
¶
An abstraction of a pipeline.
范例：
>>> 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:
Template.
reset
(
)
¶
Restore a pipeline template to its initial state.
Template.
clone
(
)
¶
Return a new, equivalent, pipeline template.
Template.
debug
(
flag
)
¶
若
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.
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.