读取/写入Popen()子进程 [英] Reading/writing to a Popen() subprocess

问题描述

我正在尝试使用python subprocess.Popen()调用与子进程进行通讯.在我的真实代码中，我正在实现一种IPC，因此我想写一些数据，读取响应，写一些其他数据，读取响应等等.因此，我不能使用Popen.communicate()，否则它在简单情况下效果很好.

I'm trying to talk to a child process using the python subprocess.Popen() call. In my real code, I'm implementing a type of IPC, so I want to write some data, read the response, write some more data, read the response, and so on. Because of this, I cannot use Popen.communicate(), which otherwise works well for the simple case.

此代码显示了我的问题.它甚至从未获得第一个响应，而挂在第一个读取结果"上.为什么?我该如何按预期进行这项工作?

This code shows my problem. It never even gets the first response, hangs at the first "Reading result". Why? How can I make this work as I expect?

import subprocess
p = subprocess.Popen(["sed", 's/a/x/g'],
                     stdout = subprocess.PIPE,
                     stdin = subprocess.PIPE)

p.stdin.write("abc\n")
print "Reading result:"
print p.stdout.readline()

p.stdin.write("cat\n")
print "Reading result:"
print p.stdout.readline()

推荐答案

如果可以，我会尝试使用Popen().communicate()，因为它可以为您带来很多好处，但是如果您完全需要使用Popen()如您所描述的，您需要使用-l选项将sed设置为在换行符之后刷新其缓冲区:

I would try to use Popen().communicate() if you can as it does a lot of nice things for you, but if you need to use Popen() exactly as you described, you'll need to set sed to flush its buffer after newlines with the -l option:

p = subprocess.Popen(['sed', '-l', 's/a/x/g'],
                     stdout=subprocess.PIPE,
                     stdin=subprocess.PIPE)

您的代码应该可以正常工作

and your code should work fine

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