Python。 subprocess.Popen的第二步截斷的第一

Question

結果在我的python腳本的snipet之下，我認爲TEMP2不會等待溫度完成運行，輸出可以是大的，但僅僅是文本。這會從temp中截斷結果（'out'），它會停止中線。從溫度'出'工作正常，直到溫度2添加。我嘗試添加time.wait（）以及subprocess.Popen.wait（TEMP）。這些都允許臨時運行到完成，這樣「出」不被截斷，但讓沒有「OUT2」擾亂鏈接過程。有任何想法嗎？

temp = subprocess.Popen(call, stdout=subprocess.PIPE) 
#time.wait(1) 
#subprocess.Popen.wait(temp) 
temp2 = subprocess.Popen(call2, stdin=temp.stdout, stdout=subprocess.PIPE) 
out, err = temp.communicate() 
out2, err2 = temp2.communicate() 

Answer 1

根據Python Docs communications（）可以接受一個流作爲輸入發送。如果更改的temp2stdin到subprocess.PIPE，把out在溝通（），數據正確管道。

#!/usr/bin/env python 
import subprocess 
import time 

call = ["echo", "hello\nworld"] 
call2 = ["grep", "w"] 

temp = subprocess.Popen(call, stdout=subprocess.PIPE) 

temp2 = subprocess.Popen(call2, stdin=subprocess.PIPE, stdout=subprocess.PIPE) 
out, err = temp.communicate() 
out2, err2 = temp2.communicate(out) 

print("Out: {0!r}, Err: {1!r}".format(out, err)) 
# Out: b'hello\nworld\n', Err: None 
print("Out2: {0!r}, Err2: {1!r}".format(out2, err2)) 
# Out2: b'world\n', Err2: None 

Answer 2

繼"Replacing shell pipeline" section from the docs：

temp = subprocess.Popen(call, stdout=subprocess.PIPE) 
temp2 = subprocess.Popen(call2, stdin=temp.stdout, stdout=subprocess.PIPE) 
temp.stdout.close() 
out2 = temp2.communicate()[0]