How to suppress console output in Python?

Question

I'm using Pygame/SDL's joystick module to get input from a gamepad. Every time I call its get_hat() method it prints to the console. This is problematic since I use the console to help me debug and now it gets flooded with SDL_JoystickGetHat value:0: 60 times every second. Is there a way I can disable this? Either through an option in Pygame/SDL or suppress console output while the function calls? I saw no mention of this in the Pygame documentation.

edit: This turns out to be due to debugging being turned on when the SDL library was compiled.

user_207384 · Answer

You can get around this by assigning the standard out/error (I don't know which one it's going to) to the null device. In Python, the standard out/error files are sys.stdout/sys.stderr, and the null device is os.devnull, so you do

sys.stdout = open(os.devnull, "w")
sys.stderr = open(os.devnull, "w")

This should disable these error messages completely. Unfortunately, this will also disable all console output. To get around this, disable output right before calling the get_hat() the method, and then restore it by doing

sys.stdout = sys.__stdout__
sys.stderr = sys.__stderr__

which restores standard out and error to their original value.

user_221818 · Answer

Here's the relevant block of code from joystick.c (via SVN at http://svn.seul.org/viewcvs/viewvc.cgi/trunk/src/joystick.c?view=markup&revision=2652&root=PyGame)

    value = SDL_JoystickGetHat (joy, _index);
#ifdef DEBUG
    printf("SDL_JoystickGetHat value:%d:
", value);
#endif
    if (value & SDL_HAT_UP) {

Looks like a problem with having debugging turned on.

user_1904943 · Answer

Building on @charleslparker's answer:

from contextlib import contextmanager
import sys, os

@contextmanager
def suppress_stdout():
    with open(os.devnull, "w") as devnull:
        old_stdout = sys.stdout
        sys.stdout = devnull
        try:  
            yield
        finally:
            sys.stdout = old_stdout

print("Now you see it")
with suppress_stdout():
    print("Now you don't")

Tests

>>> with suppress_stdout():
        os.system('play /mnt/Vancouver/programming/scripts/PHASER.WAV')

/mnt/Vancouver/programming/scripts/PHASER.WAV:

 File Size: 1.84k     Bit Rate: 90.4k
  Encoding: Unsigned PCM  
  Channels: 1 @ 8-bit    
Samplerate: 11025Hz      
Replaygain: off         
  Duration: 00:00:00.16  

In:100%  00:00:00.16 [00:00:00.00] Out:1.79k [!=====|=====!]        Clip:0    
Done.

Use this to completely suppress os.system() output:

>>> with suppress_stdout():
        os.system('play /mnt/Vancouver/programming/scripts/PHASER.WAV >/dev/null 2>&1')
>>> ## successfully executed

>>> import time
>>> with suppress_stdout():
        for i in range(3):
                os.system('play /mnt/Vancouver/programming/scripts/PHASER.WAV >/dev/null 2>&1')
                time.sleep(0.5) 
>>> ## successfully executed

Useful (e.g.) to signal completion of long-running scripts.

How to suppress console output in Python?

8 Answers