如何获得命令提示符输出？ 为什么我不能在这段代码中得到它

Question

I try to get string in command prompt by the way using "subprocess". The execution contents is to read "TOC" of CD-DA.I'm using "cdparanoia". In case of keyin on command prompt I can get "TOC".

import subprocess
class Aaa():
    def __init__(self):
        p = subprocess.Popen("cd-paranoia",stdout=subprocess.PIPE)
        out = p.communicate()[0]
        str = out.decode(encode="utf-8")
        print(str)
Aaa()

In the above code, it's displayed red string of "TOC" pressing reset button on interactive window in Visual Studio 2017. But it can't be stored in variable "str". What should I do?

Answer 1

Processes can choose to output to output or error streams. In your case you're not redirecting the error stream. You can for instance merge both output & error streams like this:

    p = subprocess.Popen("cd-paranoia",stdout=subprocess.PIPE,stderr=subprocess.STDOUT)

and the rest of your code does the job.