监控named是否开启

#!/bin/bash
port=$(nmap -sT localhost | grep ‘domain‘ |awk ‘{print $2}‘)
riqi=$(date +"%Y-%m-%d %H:%M")
if [ "$port" == "open" ];then
        echo "$riqi named is ok" >>/home/shell/namedok.txt
else
        /home/wkubuntu/named/sbin/named -c /home/wkubuntu/named/etc/named.conf &
        sleep 3       
        /home/wkubuntu/named/sbin/named -c /home/wkubuntu/named/etc/named.conf &
        echo "$riqi named is restart" >>/home/shell/namederror.txt
fi

crontab -e
*/1 * * * * /home/shell/jiangkongnamed.sh