TShark pcap filter command possibly simplified?

Object: to find the IP addresses of HTTP servers in a pcap file with a specific header string. Can or should the -l option to flush be used? One way: the following was done but am wondering if it can be shortened. If this question is too broad, please advise.

tshark -r file.pcap -T fields -e ip.src -e http.server > name.txt &&
  cat name.txt | sort | uniq -c | sort -nr | grep "xxx_xxx"