linux下shell脚本命令创建一个程序包含两个人文件 执行的话里边两个file1 和flie2能交换 ？

#!/bin/bash

[ -z $1 ] && { echo "bash file.sh FILENAME"; exit; }
[ ! -f $1 ] && { echo "bash file.sh filename"; exit; }

today=`find . -name "$1" -mtime -1`
yesterday=`find . -name "$1" -mtime +1 -mtime -10`

[ -z "$today" ] && echo "yesterday"
[ -z "$yesterday" ] && echo "today"

a=`file $1`

echo ${a#*:}