用shell编写dhcp自动获取脚本

#!/bin/bash
#
net=$(ifconfig ens33 | awk -F'[ .]+' '/inet\>/{print $3"."$4"."$5"."}')
read -p "请输入地址池开始和结束(例如：10 20）：" start end
read -p "请输入DNS地址："DNS1 DNS2
read -p "请输入最小和最大租约时间：" time1 time2
read -p "请输入网关地址：" gw
[ -d /media/cdrom ] ||  mkdir /media/cdrom
[ -d /media/cdrom/Packages ] ||  mount /dev/cdrom /media/cdrom &> /dev/null
echo "正在安装dhcp软件包,请耐心等待..."
[ $? -eq 0 ] || rpm -i /media/cdrom/Packages/dhcp-4.2.5-68.el7.centos.x86_64.rpm

cat << EOF > /etc/dhcp/dhcpd.conf
option domain-name "crushlinux.com";
option domain-name-servers $DNS1,DNS2;
default-lease-time $time1;
max-lease-time $time2;
subnet $net.0  netmask 255.255.255.0 {
range $net.$start $net.$end;
option routers $gw;
}
EOF
echo "正在尝试启动dhcpd服务"
systemctl start dhcpd
netstat -lnpu | grep :67