提前把我们要检查的网络的ip地址写入到ip.txt文本中，格式如下：
日后，如有网络增加地址，可直接写入此文本中；
检查脚本如下：
#!/bin/bash
#author: lijinzhu
#this is a check network script.
dt=$(date +%Y%m%d)
[ -f /home/vsftproot/check_${dt}.log ] && echo "Clean up expired file: $(ls /home/vsftproot/check_${dt}.log) success... Start check..." && rm -rf /home/vsftproot/check_${dt}.log
echo "system is checking the network service"
echo "Please wating..."
sleep 2
while read line
do
if ping -w 1 -c 1 $line &>/dev/null; then
echo "$line is up" >> /home/vsftproot/check_${dt}.log
else
echo "$line is down" >> /home/vsftproot/check_${dt}.log
fi
done < /root/ip.txt
echo ""
echo "done....you can see "/home/vsftproot/check_${dt}.log""