set_hostname.sh

#!/bin/bash
#-----------------<jihongrui@outlook.com>-----------------------
# 根据IP地址的后两段,设置hostname
# 192.168.11.22   set   22.11.domain.com

PTAH="/sbin:/usr/sbin:/usr/local/sbin:/bin:/usr/bin:/usr/local/bin"
export PTAH

domain='domain.com'

# 记录本机IP至这个文件
ip_file='/etc/ssh/ip.pid'

# 取的本机的IP
function Get_rip(){
if [[ -f $ip_file ]] && [[ `awk -F \= '{print $2}' $ip_file` != "" ]];then
    RIP=`awk -F \= '{print $2}' $ip_file`
else

# 检测命令
which ip &>/dev/null
if [[ $? -ge 0 ]];then
    HOSTIPS=(`/sbin/ip addr |egrep -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'|egrep -v '255|127\.0\.0\.1|0\.0\.0\.0'`)
else
    HOSTIPS=(`ifconfig |egrep -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'|egrep -v '255|127\.0\.0\.1|0\.0\.0\.0'`)
fi

# 取默认网关IP的前三位 以和 IP 做比对
DEGAWAY1=`route -nee |grep 'UG' |awk '{print $2}'|awk -F \. '{print $1"."$2"."$3}'`
DEGAWAY2=`netstat -r | grep 'default' |awk '{print $2}'|awk -F \. '{print $1"."$2"."$3}'`
if [[ "${DEGAWAY1}" == "${DEGAWAY2}" ]];then
        DEGAWAY=${DEGAWAY2}
else
        DEGAWAY=${DEGAWAY1}
fi


# 取能连接外网的IP
for ip in ${HOSTIPS};
do
        ip3=`echo ${ip} |awk -F \. '{print $1"."$2"."$3}'`
        if [[ "${ip3}" == "${DEGAWAY}" ]];then
                if [[ $(ping -c 2 223.5.5.5 &>/dev/null ; echo $?) -eq 0 ]];then
                        RIP=${ip}
                else
                        echo "IP ERROR"
                        exit 1
                fi
        fi
done
echo "RIP=${RIP}" > $ip_file
fi
}

Get_rip

HOSTIP=${RIP}

HOST=$(echo $HOSTIP |awk -F\. '{print $4"."$3".${domain}"}')

if [[ ${HOST} != "" ]] && [[ $HOSTIP != "" ]]
        then
                hostname ${HOST}
                echo "${HOSTIP}  ${HOST}" >> /etc/hosts
                echo "127.0.0.1  ${HOST}" >> /etc/hosts
                sed -i 's#^HOSTNAME\=.*$#HOSTNAME\='$(echo ${HOST})'#g' /etc/sysconfig/network
fi