How do I print out the count of unique matches with grep?

Question

Lets say I have millions of packets to look through and I want to see how many times a packet was sent to a certain port number.

Here are some of the packets:

Answer 1

See uniq -c. You'll want to pull out the bit you want, sort the result, pipe thru uniq, sort the output. Something like this maybe:

egrep '\.[0-9]+:' output.txt | sort | uniq -c | sort -nr

Clarification: I've used grep here because it's not clear what your output.txt format looks like, but you'll want to actually cut out the port number bit, perhaps via cut or awk.

Edit: To get the port, you can cut once on a period and then again on a colon:

cut -d. -f10 < output.txt | cut -d: -f1

(Or any one of a dozen other ways to accomplish the same thing.) That will give you an unsorted list of ports. Then:

cut -d. -f10 < output.txt | cut -d: -f1 | sort | uniq -c | sort -nr