我想禁止运行可执行程序的函数产生的所有终端输出。

我试图通过使用上下文管理器来抑制Python函数的输出，该上下文管理器在每次调用函数时临时重新定义stdout和stderr。这样可以抑制print函数调用产生的终端输出，但是当函数调用产生终端输出的可执行文件时，它似乎不起作用。

那么，如何抑制Python函数调用的可执行文件的输出呢？

我的代码如下。我提供了一个示例函数，该函数调用ls以尝试说明我要抑制的终端输出的种类（尽管我要处理的函数是不同的）。

#!/usr/bin/env python

import os
import subprocess
import sys

def main():

    print("hello")

    with silence():
        print("there")

    print("world")

    with silence():
        engage_command(command = "ls")

class silence(object):

    def __init__(
        self,
        stdout = None,
        stderr = None
        ):
        if stdout == None and stderr == None:
            devnull = open(os.devnull, "w")
            stdout = devnull
            stderr = devnull
        self._stdout = stdout or sys.stdout
        self._stderr = stderr or sys.stderr

    def __enter__(
        self
        ):
        self.old_stdout = sys.stdout
        self.old_stderr = sys.stderr
        self.old_stdout.flush()
        self.old_stderr.flush()
        sys.stdout = self._stdout
        sys.stderr = self._stderr

    def __exit__(
        self,
        exc_type,
        exc_value,
        traceback
        ):
        self._stdout.flush()
        self._stderr.flush()
        sys.stdout = self.old_stdout
        sys.stderr = self.old_stderr

def engage_command(
    command = None
    ):
    process = subprocess.Popen(
        [command],
        shell      = True,
        executable = "/bin/bash")
    process.wait()
    output, errors = process.communicate()
    return output

if __name__ == "__main__":
    main()

在我的特殊情况下，我正在尝试运行以下功能（而不是ls上面的功能）：

with propyte.silence():
    stream = pyaudio.PyAudio().open(
        format   = pyaudio.PyAudio().get_format_from_width(1),
        channels = 1, 
        rate     = bitrate, 
        output   = True
    )

运行时，将产生如下输出：

ALSA lib pcm_dsnoop.c:606:(snd_pcm_dsnoop_open) unable to open slave
ALSA lib pcm_dmix.c:1029:(snd_pcm_dmix_open) unable to open slave
ALSA lib pcm.c:2266:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2266:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2266:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_dmix.c:1029:(snd_pcm_dmix_open) unable to open slave
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for 4294967295, skipping unlock

我想抑制该输出。

编辑：测试由@Matthias提供的解决方案

#!/usr/bin/env python

import contextlib
import os
import subprocess
import sys

def main():

    print("hello")

    with silence():
        print("there")

    print("world")

    with silence():
        engage_command(command = "ls")

@contextlib.contextmanager
def silence():
    devnull = os.open(os.devnull, os.O_WRONLY)
    old_stderr = os.dup(2)
    sys.stderr.flush()
    os.dup2(devnull, 2)
    os.close(devnull)
    try:
        yield
    finally:
        os.dup2(old_stderr, 2)
        os.close(old_stderr)

def engage_command(
    command = None
    ):
    process = subprocess.Popen(
        [command],
        shell      = True,
        executable = "/bin/bash")
    process.wait()
    output, errors = process.communicate()
    return output

if __name__ == "__main__":
    main()

我没有成功抑制来自print或的终端输出ls，我不确定为什么。