tcpdump that writes to a file but also shows you how many packets it's collecting in realtime

Hi

I have seen F5 support use a tcpdump that writes packets to a file but you are also able to see the amount of packets captured before you hit CTRL+C. And I can't remember what the syntax for it is. I have also looked all through the man page and can't find it and tried google as well. I just want to see the amount of packets, not the actual data. I believe it's something with the 'tee' option, not sure.

tcpdump -nni 0.0 -w file.pcap ....

(14) packets captures