写一个Shell脚本，判断10.0.0.0/24网络里，当前在线的IP有哪些？

for i in 10.0.0.{1..254}
do
ping -c 2 -w 2 $i &>/dev/null
if [ $? -eq 0 ]
then
echo $i is ok!
else
echo $i is down! >>/tmp/ip_down.txt
fi
done