如何使用python中的子进程监视stdout? [英] how do I monitor stdout with subprocess in python?

问题描述

我有一个 linux 应用程序，它使用 stdin 从命令行交互运行以接受命令.我已经编写了一个包装器，使用子进程在应用程序处于后台时访问 stdin.我现在可以使用 p.stdin.write(command) 向它发送命令，但是我该如何监控它的响应呢?

I have a linux application that runs interactively from commandline using stdin to accept commands. I've written a wrapper using subprocess to access stdin while the application is backgrounded. I can now send commands to it using p.stdin.write(command) but how do I go about monitoring its responses?

推荐答案

从 p.stdout 读取以访问进程的输出.

Read from p.stdout to access the output of the process.

根据进程的作用，您可能必须小心确保不会阻塞 p.stdout 而 p 反过来阻塞其 p.stdout代码>标准输入.如果您确定每次写入时它都会输出一行，您可以简单地像这样循环交替:

Depending on what the process does, you may have to be careful to ensure that you do not block on p.stdout while p is in turn blocking on its stdin. If you know for certain that it will output a line every time you write to it, you can simply alternate in a loop like this:

while still_going:
    p.stdin.write('blah\n')
    print p.stdout.readline()

但是，如果输出更加零星，您可能需要查看 select 模块以更灵活的方式在读取和写入之间交替.

However, if the output is more sporadic, you might want to look into the select module to alternate between reading and writing in a more flexible fashion.

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