Python 3 运行 shell 命令

#python 3.5 ， win10

引入包

#os.chdir('path')

import os
import subprocess

#https://docs.python.org/3.5/library/subprocess.html?highlight=subprocess#module-subprocess

#http://ltp.readthedocs.io/zh_CN/latest/ltptest.html

Run 1 process

p1 = subprocess.Popen('cws_cmdline --input input_file.txt ',stdout=subprocess.PIPE,stderr=subprocess.PIPE [,universal_newlines=True])

#p1 = subprocess.Popen(['cws_cmdline','--input', 'input_file.txt '],stdout=subprocess.PIPE,stderr=subprocess.PIPE)

#universal_newlinews 为 True 时，输入为 str 流，(默认)为 False 时为 byte 流

output_10 = p1.communicate()[0]　　#stdin
output_11 = p1.communicate()[1]　　#stderr

Run pipe-line

p1 = subprocess.Popen('cws_cmdline --input input_file.txt ',stdout=subprocess.PIPE,stderr=subprocess.PIPE)

p2 = subprocess.Popen('pos_cmdline --input no_file.txt ',stdin=p1.stdout,stdout=subprocess.PIPE,stderr=subprocess.PIPE)

p3 = subprocess.Popen('ner_cmdline --input no_file.txt ',stdin=p2.stdout,stdout=subprocess.PIPE,stderr=subprocess.PIPE)

#if call p1|2.communicate()[0|1] before p3.communicate(), pipeline will break at p1|p2, because the before stdout|stderr pipe will be extract and not use anymore

#if call p1|2.communicate()[0|1] before p3 = constructor,  will get ValueError: I/O operation on closed file

output30 = p3.communicate()[0]　　#stdout
output31 = p3.communicate()[1]　　#stderr

#if call p1|2.communicate()[0|1] after p3.communicate(), will get close warning.

'''　　def communicate(self, input=None, timeout=None):

#...

if self.stdin:
                self._stdin_write(input)
            elif self.stdout:
                stdout = self.stdout.read()
                self.stdout.close()
            elif self.stderr:
                stderr = self.stderr.read()
                self.stderr.close()
            self.wait()

#...

'''

Run process one by one

#px.communicate()  actually run the pipe line until px, all the pipe content(p1&p2&p3.stdin&stdout&stderr pipe) will be extract and not usable any more .

#if you want to save each pipe line node's meadian content , you need to use a new pipe as   stdin=subprocess.PIPE , and use  communicate('input Popen's stdin content')

p1 = subprocess.Popen('cws_cmdline --input input_file.txt ',stdout=subprocess.PIPE,stderr=subprocess.PIPE)

output_10 = p1.communicate()[0]
output_11 = p1.communicate()[1]

str_10 = output_10.decode('utf-8')

str_11 = output_10.decode('utf-8')

p2 = subprocess.Popen('pos_cmdline --input no_file.txt ',stdin=subprocess.PIPE,stdout=subprocess.PIPE,stderr=subprocess.PIPE)

#communicate('input Popen's stdin content once if and only if stdin==subprocess.PIPE')

output_20 = p2.communicate( bytes(str_10, encoding = 'utf-8') )[0]
output_21 = p2.communicate()[1]

# for px.communicate(), only the first time call can you set the input

#or use  "universal_newlines=True" for Popen() to process str stream

p3 = subprocess.Popen('ner_cmdline --input no_file.txt ',stdin=subprocess.PIPE,stdout=subprocess.PIPE,stderr=subprocess.PIPE)

output_3 = p3.communicate( output20)
[output_30, output_31] = output_3