获取ip/mask的一个小例子

这个脚本的功能是从工大匹配出ip/mask序列对.如以下形式:
12.18.186.1/255.255.255.2
12.130.28.2/255.255.255.2
12.154.67.1/255.255.255.1
38.100.138.1/255.255.255.2
58.17.0.0/255.255.0.0
58.18.0.0/255.254.0.0
.......

初学shell编程,仅仅作为纪念

#!/bin/sh
source_file=/tmp/iplist.htm
tmp_file=/tmp/tmpfile.txt
ip_file=/tmp/ip.txt
ip_mask_file=/tmp/ip_mask.txt
n=0

echo -n "" > $ip_file
echo -n "" > $ip_mask_file
wget -O $source_file http://hitsun.hit.edu.cn/zxiplist.htm

echo "Start to analyse the source file..."

sed -n 's/\([0-9]*\.[0-9]*\.[0-9]*\.[0-9]\)/$\1$/p' $source_file | cut -d$ -f2 > $tmp_file
cat $tmp_file | while read ip
do
    tmp=$(expr $n % 3)
    if [ $tmp -eq 0 ]; then
        echo $ip >> $ip_file
        ip_bak=$ip
    fi
    if [ $tmp -eq 2 ]; then
        ip_bak=$ip_bak"/"$ip
        echo $ip_bak >> $ip_mask_file
    fi
    
    n=$(expr $n + 1)
done
echo "Done"