从控制台获取标准输出 [英] Getting stdout from console

问题描述

我正在尝试制作一个Python脚本，该脚本将使用dd if=/dev/sda of=/dev/sdb

I'm trying to make a python script that would clone(ISO image) one usb stick to another using dd if=/dev/sda of=/dev/sdb

这是我的问题: 我想创建进度条，显示已完成的操作.

Here's my problem: I want to create progress bar showing what is done.

我尝试过:

1. 在第二个USB记忆棒上查看存储空间，但这无法正常工作，因为ISO映像还会扫描未使用的空间
2. 通过将status=progress添加到dd命令中，我可以在终端中获得进度，但是我不知道如何从python访问stdout.我尝试了subprocess.Popen,run(stdout = PIPE)有无shell = True 用.read()，.read(1)，.readline()或communicate()读取process.stdout.对我没有任何帮助.( https://www.endpoint.com/blog/2015/01/28/getting-realtime-output-using-python )

1. Looking at storage space at second usb stick, but this doesn't work beacause ISO image scans also unused space
2. By adding status=progress to dd command I can get progress in terminal but I can't figure how to access stdout from python. I tried subprocess.Popen,run(stdout = PIPE) with and without shell = True reading process.stdout with .read(), .read(1), .readline() or communicate(). Nothing worked for me.(https://www.endpoint.com/blog/2015/01/28/getting-realtime-output-using-python)

我可以在python shell中看到进度，但是.read()函数总是卡住.

I can see progress going on in python shell but .read() function always get stuck.

我关注的部分代码:

comm = 'sudo dd if=/dev/sda of=/dev/sdb'
cloning = subprocess.Popen(shlex.split(comm),stdout = PIPE,text = True)
while True:
    print(cloning.stdout.read())

我想要可以工作的东西:

I want something that would work like:

while True:
    progress = cloning.stdout.read()
    update_bar(progress)

我在Raspberry上使用python 3.7

I'm using python 3.7 on Raspberry

感谢帮助

推荐答案

您使用status=progress处于正确的轨道，但是它输出到stderr，而不是stdout.如果您执行stderr = PIPE，然后从cloning.stderr而不是cloning.stdout读取，它将起作用.

You were on the right track with status=progress, but it outputs to stderr, not stdout. If you do stderr = PIPE and then read from cloning.stderr instead of cloning.stdout, it will work.

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