pipes
— Shell 管道接口
¶
源代码： 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()
被要求。
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'
pipes.
quote
(
s
)
¶
Deprecated since version 2.7:
Prior to Python 2.7, this function was not publicly documented. It is finally exposed publicly in Python 3.3 as the
quote
function in the
shlex
模块。
Return a shell-escaped version of the string s . The returned value is a string that can safely be used as one token in a shell command line, for cases where you cannot use a list.
This idiom would be unsafe:
>>> filename = 'somefile; rm -rf ~' >>> command = 'ls -l {}'.format(filename) >>> print command # executed by a shell: boom! ls -l somefile; rm -rf ~
quote()
lets you plug the security hole:
>>> command = 'ls -l {}'.format(quote(filename)) >>> print command ls -l 'somefile; rm -rf ~' >>> remote_command = 'ssh home {}'.format(quote(command)) >>> print remote_command ssh home 'ls -l '"'"'somefile; rm -rf ~'"'"''
The quoting is compatible with UNIX shells and with
shlex.split()
:
>>> remote_command = shlex.split(remote_command)
>>> remote_command
['ssh', 'home', "ls -l 'somefile; rm -rf ~'"]
>>> command = shlex.split(remote_command[-1])
>>> command
['ls', '-l', 'somefile; rm -rf ~']
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
)
¶
拷贝 infile to outfile through the pipe.