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Date: Sun, 31 May 2015 16:01:33 +0300
From: Solar Designer <>
Subject: Re: [john-core] Getting John's stdout unbuffered for Johnny

On Sat, May 30, 2015 at 08:44:46AM +0300, Solar Designer wrote:
> Shinnok, just let me know what the Johnny team decides on this.  If you
> ask me to, I think I'll add a call to:
> setvbuf(stdout, NULL, _IOLBF, 0);
> to john.c: john_init().
> It is important to keep stdout with its default buffering when john is
> invoked via one of the un* symlinks, since they're commonly used with
> stdout pointing at a disk file.

I've just committed the change documented as:

Set stdout to line buffered (rather than potentially fully buffered), except
for "--stdout", "--show", and auxiliary programs such as "unshadow".;r2=1.73

However, I am not sure this was such a good idea.  Even with these
exceptions, there may still be cases where the buffering was helpful.
For example, I sometimes run "./john ... > /dev/null" when I am testing
on huge numbers of easily crackable hashes.  Line buffering will make
this run considerably slower.  Maybe this means that we need a --quiet
or --silent option or/and a key or/and a john.conf setting to mute
printing of guesses to stdout.


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