tcpdump | grep pattern > capture nothing got

[Florent Peterschmitt]

On 20/11/13 23:38, Dimitry Andric wrote:
> On 20 Nov 2013, at 19:44, Florent Peterschmitt <florent at 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
> 

It works, thank you. But, I didn't have to do this on a GNU/Linux
machine. Is that normal?

-- 
Florent Peterschmitt           | Please:
florent at peterschmitt.fr        |  * Avoid HTML/RTF in E-mail.
+33 (0)6 64 33 97 92           |  * Send PDF for documents.
http://florent.peterschmitt.fr |  * Trim your quotations. Really.
Proudly powered by Open Source | Thank you :)

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 901 bytes
Desc: OpenPGP digital signature
URL: <http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20131121/e4ebc802/attachment.sig>