redirect the stdout of an third-party module to /dev/null

Question

Suppose such a minor program to play sound

#!/usr/bin/python3
from pydub import AudioSegment
from pydub.playback import play

bell_sound = AudioSegment.from_wav("/home/me/Music/audio/bell.wav")
play(bell_sound)

Upon running it, the terminal got multiple lines of propts

In [8]: run report_time_example.py  
Input #0, wav, from '/tmp/tmpsc7u87_e.wav':   0KB sq=    0B f=0/0
  Duration: 00:00:01.62, bitrate: 176 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 11025 Hz, 1 channels, s16, 176 kb/s
   1.43 M-A:  0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0

Manually redirect the output to /dev/null

   !python report_time_example.py  &> /dev/null

How could get the job done inside the python code body.

you could check in source code if it is even possible. Maybe functions in this module have some option for this. Or maybe you will have to modify source code.\ — furas, Jul 11 '19 at 00:47
you may try to assign own function/class to `sys.stderr` but it can blocks all error messages. — furas, Jul 11 '19 at 00:49

score 3 · Answer 1 · answered Jul 11 '19 at 00:56

The contextlib module offers context managers to redirect stdout and stderr for precisely this purpose:

import contextlib
import os

with open(os.devnull, 'w') as null, \
     contextlib.redirect_stdout(null), contextlib.redirect_stderr(null):
    bell_sound = AudioSegment.from_wav("/home/me/Music/audio/bell.wav")
    play(bell_sound)

While in the with block, stdout and stderr are redirected; when the block is exited, the original handles are restored.

Note: redirect_stdout was introduced in 3.4, and redirect_stderr in 3.5; if you're still on 2.7 or the like, your only option is reassigning sys.stdout/sys.stderr manually, or using os.dup2 to replace the underlying file descriptors, but I'd recommend using modern Python first.

redirect the stdout of an third-party module to /dev/null

1 Answers1