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脚本功能

定时检查域名的连通性，
如果不通，则从ip列表中遍历检查连通性
ip通则与域名绑定到 hosts 文件中

#!/bin/bash

DOMAIN=api.weixin.qq.com
IP_LIST='192.168.1.1 192.168.1.2 192.168.1.3 43.129.2.204 192.168.1.4'
HOSTS=/etc/hosts
BACKUP_DIR=backup

while true; do
    echo "=======$(date +"%Y%m%d %H:%M:%S")======"
    echo "checking connection of domain: ${DOMAIN}"
    if ! ping -c 1 ${DOMAIN} &> /dev/null
    then
        echo "domain connection is down"
        for ip in $IP_LIST
        do
            echo "checking connection of ip: ${ip}"
            if ping -c 1 $ip &> /dev/null
            then
                # backup hosts 当前时间
                # Get current date and time
                CURRENT_TIME=$(date +"%Y%m%d_%H%M%S")
                
                # Create backup directory if it doesn't exist
                mkdir -p ${BACKUP_DIR}
                
                # Backup hosts file with current date and time appended to the filename
                cp ${HOSTS} ${BACKUP_DIR}/hosts_${CURRENT_TIME}
                
                echo "connection is ok, write ${ip} to the file of: ${HOSTS}"
                # Check if the domain does not exist in the hosts file
                if ! grep -q "${DOMAIN}" ${HOSTS}; then
                    # If it does not exist, append the IP and domain to the hosts file
                    echo "${ip} ${DOMAIN}" >> ${HOSTS}
                else
                    sed -i -e "/^[^#]/s/.* ${DOMAIN}/${ip} ${DOMAIN}/" $HOSTS
                fi

                break
            fi
        done
    else
        echo "domain connection is ok"
    fi
    echo "sleeping for 10s"
    sleep 10
done