python子进程通信()块 [英] python subprocess communicate() block

问题描述

我正在使用子进程模块调用外部程序(plink.exe)来登录服务器；但是当我调用通信来读取输出时，它是阻塞的.代码如下:

I am using the subprocess module to call an external program (plink.exe) to log-in to a server; but when I call communicate to read the output, it is blocking. The code is below:

 import subprocess
 process = subprocess.Popen('plink.exe hello@10.120.139.170 -pw 123456'.split(), shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
 print process.communicate() #block here

我知道这个块是因为 plink.exe 它还在运行；但我需要在子进程终止之前读取输出.有什么办法吗?

I know the block is because plink.exe it still running; but I need to read the output before the subprocess terminates. Is there anyway to do that?

推荐答案

communicate 方法的全部目的是等待进程完成并返回所有输出.如果您不想等待，请不要调用 communicate.而是从 stdout 或 stderr 属性读取输出.

The whole purpose of the communicate method is to wait for the process to finish and return all the output. If you don't want to wait, don't call communicate. Instead, read from the stdout or stderr attribute to read the output.

如果进程同时输出到 stdout 和 stderr (并且您想分别读取它)，则必须小心地从两者中实际读取而不会阻塞，或者你可以死锁.这在 Windows 上相当困难，您可能希望使用 pexpect 模块.

If the process outputs to both stdout and stderr (and you want to read it separately), you will have to be careful to actually read from both without blocking, or you can deadlock. This is fairly hard on Windows, and you may wish to use the pexpect module instead.

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