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Date:      Wed, 04 Aug 2010 10:51:08 -0400
From:      "Alexandre \"Sunny\" Kovalenko" <gaijin.k@ovi.com>
To:        Gabor Kovesdan <gabor@FreeBSD.org>
Cc:        poyopoyo@puripuri.plala.or.jp, current@FreeBSD.org
Subject:   Re: bsdgrep does not work with tail -f | grep combination
Message-ID:  <1280933468.2752.2.camel@RabbitsDen>
In-Reply-To: <4C585E44.5030608@FreeBSD.org>
References:  <86eiefhalp.wl%poyopoyo@puripuri.plala.or.jp> <4C585E44.5030608@FreeBSD.org>

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On Tue, 2010-08-03 at 20:21 +0200, Gabor Kovesdan wrote:
> Em 2010.08.03. 19:25, poyopoyo@puripuri.plala.or.jp escreveu:
> > Hi,
> >
> > It seems bsdgrep does not work when piped from tail -f.
> > I'm running r210728.
> >
> > term0$ jot 10>  /tmp/1
> > term0$ tail -f /tmp/1 | grep 0
> > [no output]
> >
> > otherterm$ jot 10>>  /tmp/1
> > [no output to term0]
> >
> > =3D=3D=3D=3D=3D
> >
> > with GNU grep:
> >
> > term0$ tail -f /tmp/1 | gnugrep 0
> > 10
> > otherterm$ jot 10>>  /tmp/1
> > [on term0]
> > 10
> > 10
> >=20=20=20=20
> I've checked on 8.0 and GNU grep doesn't output anything either for me.=
=20
> If you use tail -f, you will enter more lines and end it with EOF, won't=
=20
> you? And then BSD grep will process the input and print out matches. I=20
> don't think it's bad behaviour in itself but if you can explain why you=
=20
> think it's bad I'm willing to change it.
>=20
I am not sure it is specific to the GNU grep -- below is the example
from AIX 5.3:

sunny@irptdev_1>tail -f engine.log | grep Hello=20=20=20=20
Aug  4 10:41:39 irptdev_1 local3:debug sunny: Hello Wed Aug 4 10:41:39
EDT 2010=20
Aug  4 10:41:46 irptdev_1 local3:debug sunny: Hello Wed Aug 4 10:41:46
EDT 2010=20
Aug  4 10:41:57 irptdev_1 local3:debug sunny: Hello Wed Aug 4 10:41:57
EDT 2010=20

I am doing=20

sunny@irptdev_1>logger -p local3.debug Hello `date`
sunny@irptdev_1>logger -p local3.debug Hello `date`
sunny@irptdev_1>logger -p local3.debug Hello `date`

from different terminal window.

HTH,
--=20
Alexandre Kovalenko (=D0=9E=D0=BB=D0=B5=D0=BA=D1=81=D0=B0=D0=BD=D0=B4=D1=80=
 =D0=9A=D0=BE=D0=B2=D0=B0=D0=BB=D0=B5=D0=BD=D0=BA=D0=BE)



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