shell脚本中按日期遍历文件

#!/bin/sh
datebeg=20120412
beg_s=`date -d "$datebeg" +%s`

for ((DAY=0;DAY<=31;DAY++));
do
DAY1=`date -d @$beg_s +"%Y-%m-%d"`
A1=`cat file.${DAY1}.txt|cmd1|cmd2|blablabla...`
B2=`cat file2.${DAY1}.txt|cmd1|cmd2|blablabla...`
echo "$DAY1"
echo "scale=2;$A1*100/$B2" | bc

beg_s=$((beg_s+86400))
done

备注：循环中通过BC命令对遍历的文件进行一些数值计算