grep -Eo '([a-z,A-Z,0-9]+\.){2,}[a-z,A-Z,0-9]+' | sort | uniq -c | sort -r | sed -nr 's/^[ ]*//p'
- grep -o只输出匹配到的内容
- sort排序
- uniq -c 统计连续重复行
- sort -r 按重复数反向排序
- sed 将每行前面的空格删掉

grep -Eo '([a-z,A-Z,0-9]+\.){2,}[a-z,A-Z,0-9]+' | sort | uniq -c | sort -r | sed -nr 's/^[ ]*//p'