观测脚本 网关【1】

#!/usr/bin/bash

trap call_event 11

call_event(){
  exit
}

INTERFACE=eth0
DEST_IP_NCOL=1
GW_IP_NCOL=2

WATCH_DEST_IP="0.0.0.0"
GW_IP="172.21.7.1"

route -n | awk '{if(NR>2){print $0}}' | while read info ; do
   dest_ip=$(echo $info  | grep ${INTERFACE} | cut -d' ' -f${DEST_IP_NCOL})
   gw_ip=$(echo $info | grep ${INTERFACE} | cut -d' ' -f${GW_IP_NCOL})
   if [[ "$WATCH_DEST_IP" == "$dest_ip" ]] && [[ "$GW_IP == $gw_ip" ]] ; then
	   kill -s 11 $$
   fi
done
route add default gw $GW_IP $INTERFACE

watchsys.sh

while $(sleep 1) ; do ./watchsys.sh ; done

exit 指令只会退出当前管道，不会退出脚本的执行进程