Shell扫描所在网段存活主机

ipaddr=`/usr/sbin/ip a | grep $1 | grep inet | awk '{print $2}'`
netmask=`echo ${ipaddr} | awk -F "/" '{print $2}'`
if [ $netmask -eq 24 ];then
subnets=`echo ${ipaddr} | awk -F "." '{print $1"."$2"."$3"."}'`
acount=0
for i in `seq 1 25`
do
/usr/bin/ping ${subnets}${i} -c 2 > /dev/null
if [ $? -eq 0 ];then
echo "${subnets}$i is online"
let count+=1
else
echo "${subnets}$i is not online"
fi
done
fi
echo "There are $count hosts onlie"