This code counts consecutive lines in standard input

consecutive_line_counter.rb

cnt = 1
prev_s = ""

while s = gets do
        s.chomp!
        if prev_s == "" then
                prev_s = s
                next
        end

        if s == prev_s then
                cnt += 1
        else
                print prev_s, ",", cnt, "\n"
                prev_s = s
                cnt = 1
        end
end

print prev_s, ",", cnt, "\n"