Date: Wed, 20 Nov 2013 23:38:44 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Florent Peterschmitt <florent@peterschmitt.fr> Cc: freebsd-stable stable <freebsd-stable@freebsd.org> Subject: Re: tcpdump | grep pattern > capture nothing got Message-ID: <966AFB1F-D273-4754-96AC-01298FBF6F42@FreeBSD.org> In-Reply-To: <528D0302.7090906@peterschmitt.fr> References: <528D0302.7090906@peterschmitt.fr>
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[-- Attachment #1 --] On 20 Nov 2013, at 19:44, Florent Peterschmitt <florent@peterschmitt.fr> wrote: > I use FreeBSD 10.0-BETA3 amd64, upgraded from 9.2-RELEASE with > freebsd-update. > > I was capturing with tcpdump and doing some grep on it: > > # tcpdump -li nfe0 port 53 | grep Refused > capture.txt > > I was surprised that capture.txt is totally empty. If I don't redirect > the output, then it writes what I need on stdout. Try grep --line-buffered instead (which incurs a performance penalty, but you probably don't care in this case). BSD grep also supports this option. -Dimitry [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.22 (Darwin) iEYEARECAAYFAlKNOf0ACgkQsF6jCi4glqNHLgCgsWLN3cdAo6+EOkd/x791kZgz SZ0AoMWrGzH6pjILQBtBwrDYJpdQ1LiT =lku9 -----END PGP SIGNATURE-----
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