Programming Forums > Script Programming > Python

titaniumdecoy · Jun 30th, 2006, 2:17 PM

Is there a way to suppress output to stdout in Python? I am importing a module written by someone else that I do not want to modify which prints status messages while it is running. Is there an easy way to prevent these messages from being printed, then allowing my program to print its own messages? I assume the solution to this would be to redirect stdout, which I might look into, but is that the easiest/standard way to do this? Thanks.

Arevos · Jun 30th, 2006, 2:29 PM

I'm unfamiliar with OS X filesystems, but since they're Unix-based, presumably they have some manner of "black hole" file that swallows up all data piped to it. Under Linux, /dev/null fulfils this function.

(Toggle Plain Text)

import sys
output = sys.stdout
sys.stdout = open("/dev/null", "w")
print "Hello"
output.write("Hello\n")

There may also be a more crossplatform way of handling the problem. Perhaps by creating a pipe with os.pipe and redirecting sys.stdout to it. But then one may have problem of the pipe buffer growing too large.

Arevos · Jun 30th, 2006, 2:38 PM

I've also discovered this technique, which works on all variations of "print" I could think of, but I can't be sure if it's completely foolproof:

(Toggle Plain Text)

class Blackhole:
    def write(self, *args):
        pass

sys.stdout = Blackhole()

titaniumdecoy · Jun 30th, 2006, 2:43 PM

Thanks. However, this script is actaully running on a windows machine. I tried the following:

(Toggle Plain Text)

sys.stdout = open('C:\junk.txt', 'w')

But it doesn't seem to make any difference. I've tried sys.stdout = '' and a bunch of other things, but when I type sys.stdout, it always prints <wx.py.pseudo.PseudoFileOut instance at 0x01BC25A8>. For some reason I am unable to change the sys.stdout variable, or so it would seem.

EDIT: The Blackhole technique doesn't seem to work either. Thanks though.

Arevos · Jun 30th, 2006, 2:46 PM

Try doing the same thing with sys.stderr instead.

titaniumdecoy · Jun 30th, 2006, 2:48 PM

Oops, I put the Blackhole code too late in my code. It works now, thanks.

Jun 30th, 2006, 2:17 PM	#1
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 908 Rep Power: 3	Suppressing output Is there a way to suppress output to stdout in Python? I am importing a module written by someone else that I do not want to modify which prints status messages while it is running. Is there an easy way to prevent these messages from being printed, then allowing my program to print its own messages? I assume the solution to this would be to redirect stdout, which I might look into, but is that the easiest/standard way to do this? Thanks.

Jun 30th, 2006, 2:29 PM	#2
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	I'm unfamiliar with OS X filesystems, but since they're Unix-based, presumably they have some manner of "black hole" file that swallows up all data piped to it. Under Linux, /dev/null fulfils this function. (Toggle Plain Text) import sys output = sys.stdout sys.stdout = open("/dev/null", "w") print "Hello" output.write("Hello\n") import sys output = sys.stdout sys.stdout = open("/dev/null", "w") print "Hello" output.write("Hello\n") There may also be a more crossplatform way of handling the problem. Perhaps by creating a pipe with os.pipe and redirecting sys.stdout to it. But then one may have problem of the pipe buffer growing too large.

Jun 30th, 2006, 2:38 PM	#3
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	I've also discovered this technique, which works on all variations of "print" I could think of, but I can't be sure if it's completely foolproof: (Toggle Plain Text) class Blackhole: def write(self, args): pass sys.stdout = Blackhole() class Blackhole: def write(self, args): pass sys.stdout = Blackhole()

Jun 30th, 2006, 2:43 PM	#4
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 908 Rep Power: 3	Thanks. However, this script is actaully running on a windows machine. I tried the following: (Toggle Plain Text) sys.stdout = open('C:\junk.txt', 'w') sys.stdout = open('C:\junk.txt', 'w') But it doesn't seem to make any difference. I've tried sys.stdout = '' and a bunch of other things, but when I type sys.stdout, it always prints <wx.py.pseudo.PseudoFileOut instance at 0x01BC25A8>. For some reason I am unable to change the sys.stdout variable, or so it would seem. EDIT: The Blackhole technique doesn't seem to work either. Thanks though.

Jun 30th, 2006, 2:48 PM	#6
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 908 Rep Power: 3	Oops, I put the Blackhole code too late in my code. It works now, thanks. Last edited by titaniumdecoy; Jun 30th, 2006 at 3:05 PM.

Jun 30th, 2006, 2:46 PM	#5
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	Try doing the same thing with sys.stderr instead.

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Programming Forums > Script Programming > Python

Suppressing output