ubuntu11.04的gnome控制台导致xwindow崩溃的问题

请问一下程序哪里错了？？？

#!/bin/bash
#Program:
#每隔一小时备份一次png文件
#History:
#2010/4/30 First release
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH

echo "this program helps you to backup the png files each hour."
backdir="./backup"
if ![ -d backdir ];then
mkdir $backdir
fi
flag="y";
while [ "$flag" = "y" ]
do
minute=`date+%M`
next=$(($minute%5))
if [ $next -eq"0" ];then
echo "backuping..."
cp *.png $backdir
echo "finished"
sleep 60
echo -p"Do you want to wait 5 minutes to backup again?y/n" flag
fi
done

谢谢