script程序运行速度问题

hiipm

我有一个程序，需要读取一个文件中的每行，然后进行分类操作，但是程序运行速度很慢，不知道怎样来提高一下运行速度，肯求各位达人宝贵建议，程序如下：
SEQ=0
while read "LINE"
do

  PAGE_CHECK=`echo "$LINE" | cut -c 1-5`
  if [ "$PAGE_CHECK" = "PAGNO" ];then

    PAGE_NO=`echo "$LINE" | cut -c 11`

    PAGE_1_CHECK=`echo "$LINE" | cut -c 1-6`
    if [ "$PAGE_1_CHECK" = "PAGNO1" ];then

       SEQ=$(($SEQ + 1 ))
    fi

    if [ "$SEQ" = "4" ];then
      SEQ=1
    fi

    if [ "$SEQ" = "1"  ];then
       if [ "$PAGE_NO" = "1" ];then
          echo "om987" >> output.DAT
         
       elif [ "$PAGE_NO" = "3" ];then
          echo "om988" >> output.DAT

       elif [ "$PAGE_NO" = "5" ];then
          echo "om989" >> output.DAT

       elif [ "$PAGE_NO" = "2" ];then
          echo "$LINE" >> output.DAT
       elif [ "$PAGE_NO" = "4" ];then
          echo "$LINE" >> output.DAT
       elif [ "$PAGE_NO" = "6" ];then
          echo "$LINE" >> output.DAT
       fi
     fi
    if [ "$SEQ" = "2" ];then
        if [ "$PAGE_NO" = "1" ];then
          echo "om985" >> output.DAT

       elif [ "$PAGE_NO" = "3" ];then
         echo "om984" >> output.DAT

       elif [ "$PAGE_NO" = "5" ];then
          echo "om989" >> output.DAT

       elif [ "$PAGE_NO" = "2" ];then
          echo "$LINE" >> output.DAT
       elif [ "$PAGE_NO" = "4" ];then
          echo "$LINE" >> output.DAT
       elif [ "$PAGE_NO" = "6" ];then
          echo "$LINE" >> output.DAT
        fi
       fi
    if [ "$SEQ" = "3" ];then
        if [ "$PAGE_NO" = "1" ];then
          echo "om980" >> output.DAT
       elif [ "$PAGE_NO" = "3" ];then
          echo "om981" >> output.DAT

       elif [ "$PAGE_NO" = "5" ];then
          echo "om982" >> output.DAT

       elif [ "$PAGE_NO" = "2" ];then
          echo "$LINE" >> output.DAT
       elif [ "$PAGE_NO" = "4" ];then
          echo "$LINE" >> output.DAT
       elif [ "$PAGE_NO" = "6" ];then
          echo "$LINE" >> output.DAT
        fi
      fi

  else
  echo "$LINE" >> output.DAT
  fi
done < input.DAT
exit 0

hiipm

ps:这个程序顺序读取input.DAT中的每行字符串，然后查找“page_no”"page_no1"字段，如果有的话，进行插入output.DAT文件的一些操作，大部分时间消耗在顺序读取input.DAT中每行字符串的操作上了