linux shell 关键字查找，返回OK 否则NO

本人在XXX银行在linux运维，根据工作的需要写了简单的脚本；需求是在一台linux服务器上，为确保磁盘可用率在正常范围之内，通指定脚本将信息打印在/tmp的日志中，此脚本省略。结合外部厂商的监控系统，写下此脚本查找磁盘使用率日志的关键字，配置在监控系统，每五分钟执行一次，返回OK，磁盘使用率正常，否则反之。

#!/bin/bash
#Date:2017-01-22
#Editor:qiuqingyun
#Email:[e-mail]
#find character word by cmd:while wc if expr
#if print OK word is not change;but print ERROR it is that anyone has changed
lines=`wc -l /opt/ETL.txt|awk '{print $1}'`
startLine=4
while [ $lines -ge $startLine ]
do
        WordF=`cat /opt/ETL.txt|awk 'NR=='$lines'{print $7}'`
        WordS=`cat /opt/ETL.txt|awk 'NR=='$lines'{print $8}'`

        if [ "$WordF" == "ready" ]&&[ "$WordS" == "up" ];then

                lines=`expr $lines - 1`
                if [ $lines -eq 4 ];then
                        echo "OK"
                fi
                continue

        else
                echo "ERROR"
                break
        fi

done