Python 3 Run shell command

#python 3.5, Win10

Introduction Package

#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)

When #universal_newlinews is True, the input is the STR stream, (default) is False when the byte stream

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'll break at P1|p2, because the before Stdout|stderr p Ipe would be extract and not use anymore

#if call P1|2.communicate () [0|1] Before P3 = constructor, would 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 (), 'll 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) would 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 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

Python 3 Run shell command