Wireshark-users: [Wireshark-users] Using tshark to extract empty fields from pcap files

From: "Mark Sass" <thesassman@xxxxxxxxxxx>
Date: Wed, 26 Mar 2008 16:06:50 -0500
All,
    I am trying to extract fields from pcap files using tshark.  I am currently using a format like this:
 
tshark -r pcapfile -R "tcp.port eq xxx" -Tfields -e field1 -e field2
 
 
I don't see the fields I wanted listed on the wireshark display filter reference listing, and when looking at the pcap files after conversion to PDML, the fields show up like this:
 
<field name="" show"data I want">
 
I can extract the data from pdml since I can use regular expressions in python to retreieve it, but I would rather get it from the pcap file instead of having to convert it to pdml and extract it.  Any way I can do this using tshark at the command line? 
 
Thanks,
    Mark, thesassman@xxxxxxxxxxx