写一个脚本，实现判断网络里，当前在线用户的IP有哪些

判断是否在线：ping通，ping通后，返回值为0
root@123 [~]# cat 6.sh
#!bin/bash
for n in `seq 254`
do

ping -c2 204.45.51.$n >/dev/null 2>&1
if [ $? -eq 0 ]
then
echo “204.45.51.$n is up”>>/root/uplist.txt
else
echo “204.45.51.$n is down” >>/root/downlist.txt
fi

done

后台运行

sh 6.sh &

查看结果

root@123 [~]# cat uplist.txt
204.45.51.100 is up
204.45.51.101 is up
204.45.51.102 is up
204.45.51.103 is up
204.45.51.104 is up
204.45.51.110 is up
204.45.51.111 is up
204.45.51.112 is up

 

root@123 [~]# cat downlist.txt
204.45.51.7 is down
204.45.51.8 is down
204.45.51.7 is down