-i <capture interface> | -
Set the name of the network interface or pipe to use for live packet capture.
Network interface names should match one of the names listed in "tshark -D" (described above); a
number, as reported by "tshark -D", can also be used. If you're using UNIX, "netstat -i" or
"ifconfig -a" might also work to list interface names, although not all versions of UNIX support the
-a option to ifconfig.
If no interface is specified, TShark searches the list of interfaces, choosing the first non-loopback
interface if there are any non-loopback interfaces, and choosing the first loopback interface if
there are no non-loopback interfaces. If there are no interfaces at all, TShark reports an error and
doesn't start the capture.
Pipe names should be either the name of a FIFO (named pipe) or ``-'' to read data from the standard
input. Data read from pipes must be in standard libpcap format.
Note: the Win32 version of TShark doesn't support capturing from pipes!