Sorting/filtering/counting text data

Let's assume we'd like to count the most hit firewall rules parsing the log:

$ cat firewall.log  | grep -v -E '^$' | grep -v date | cut -d\; -f4 | cut -d\= -f2 | sort -n | uniq -c | sort

remove blank lines: grep -v -E '^$'
remove lines with 'date' in them: grep -v date
cut out field "rule=XX": cut -d\; -f4 (delimiter: ";" and print field 4)
cut out rule numbers: cut -d\= -f2 (delimiter: "=" and print field 2)
sort lines numerically: sort -n
count number of times the rule number appears: uniq -c

For reference, this is the firewall log's content:

$ cat firewall.log
date:25-mar
source=10.1.1.1;destination=192.168.1.1;port=80;rule=3
source=10.1.1.1;destination=192.168.1.1;port=80;rule=3
source=10.1.1.1;destination=192.168.1.1;port=21;rule=2
source=10.1.1.1;destination=192.168.1.1;port=22;rule=1