#!/bin/bash
filename="./input.txt"
num=0
cat $filename | while read line
do
    if [[ `echo $line | grep '帐号'` != "" ]]; then
        user=`echo $line | awk '{print $2}'`
        num=$(expr $num + 1)
    elif [[ `echo $line | grep '密码'` != "" ]]; then
        pass=`echo $line | awk '{print $2}'`
        num=$(expr $num + 1)
    fi

    if [[  $num == 2 ]]; then
        echo "匹配到: $user, $pass"
        echo "$user,$pass" >> ./output.txt
        num=0
    fi
done

例

----------------------------
afdkjakdsjfkja
adsfkdasjfk
网址  http://www.a.com
帐号  userA
密码  passA
afdkjakdsjfkja
adsfkdasjfk
网址  http://www.b.com
帐号  userB
密码  passB
----------------------------
http://www.test.com
网址  http://www.c.com
帐号  userC
密码  passC
http://www.test.com