Wireshark-users: Re: [Wireshark-users] tshark buffered packet dissection -- no realtime output?
From: Ralph Schmieder <ralph.schmieder@xxxxxxx>
Date: Sat, 13 Jan 2018 09:45:51 +0100
Thanks for this, Lee.

But no, it's the same result. In fact, I used that option in curl (and also tried with stdbuf -o0). Would have been surprised if the results were different since the "-i -" does deliver the packets in / close-to real-time which seems to proof that the issue is not buffering in curl but in tshark.

Thanks,
-ralph


On 01/12/2018 08:31 PM, Lee wrote:
On 1/12/18, Ralph Schmieder <ralph.schmieder@xxxxxxx> wrote:
running tshark on Fedora 26 (TShark (Wireshark) 2.2.8
(wireshark-2.2.8)). I get packets in pcap-ng format from a REST API
which I feed via stdin into tshark like this:

curl $API | tshark -l -r - -T text

This basically works. However, the output is buffered, despite using the
'-l' option. E.g. only after a couple of packets have arrived, the
buffer is flushed and the dissected packets are printed. I also
experimented with stdbuf for the curl command but that didn't help
either.
does "curl --no-buffer $API" make any difference?

        -N, --no-buffer
               Disables the buffering of the output stream. In normal
work situations, curl will use a standard  buffered  output
               stream  that  will  have  the effect that it will output
the data in chunks, not necessarily exactly when the data
               arrives.  Using this option will disable that buffering.

Regards,
Lee
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