ubuntu1804修改IP地址方式及脚本

sed -rn '/((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})(\.((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})){3}/p' 50-cloud-init.yaml

其中-rn是指 r是指使用扩展的正则表达式，n是不打印全部行，只打印匹配到的行
关键正则是((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})(\.((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})){3}，他只会匹配合法的ip地址，像999.0.0.0这类的非ip地址不会匹配到

修改ip地址命令

sed -ri 's/- ((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})(\.((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})){3}\/[0-9]{1,2}/- 1.2.4.6\/23/' 50-cloud-init.yaml

完整脚原本了

#!/bin/bash

if [ "$(id -u)" != "0" ]; then
   echo "只有root用户才能运行" 1>&2
   exit 1
fi

ipreg="((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})(\.((2(5[0-5]|[0-4][0-9]))|[0-1]?[0-9]{1,2})){3}"
destfile=/etc/netplan/50-cloud-init.yaml
echo "-----"
echo 请按提示输入，如不作改变，请直接回车。
echo 设置完毕后，请再次确认配置，按Y开始修改。
echo "-----"
nowipmask=`sed -rn "/- ${ipreg}\/([0-9]$|[1-2][0-9]|3[0-2])/p" $destfile`
nowipmask=${nowipmask:14}
nowip=${nowipmask%/*}
nowmask=${nowipmask#*/}

#sed -ri "s/gateway4: ${ipreg}$/gateway4: ${gateway}/" $destfile
nowgateway=`sed -rn "/gateway4: ${ipreg}/p" $destfile`
nowgateway=${nowgateway:22}

nowdnsip=`sed -rn "/- ${ipreg}$/p" $destfile`
nowdnsip=${nowdnsip:18}
echo $nowdnsip

while true; do
    echo -en "请输入IP地址(${nowip}): \t"
    read ipaddr
    if [[ $ipaddr = "" ]];then
	ipaddr=$nowip
    fi
    if [[ $ipaddr =~ ^$ipreg$ ]]; then
        break;
    else
        echo "输入的ip地址不合法"
    fi
done;

while true; do
    echo -en "请输入子网掩码(${nowmask}): \t\t"
    read mask
    if [[ $mask == "" ]];then
	mask=$nowmask
    fi
    if [[ $mask =~ ^([8-9]|[1-2][0-9]|3[0-2])$ ]]; then
        break;
    else
        echo "输入的mask地址不合法"
    fi
done;

while true; do
    echo -en "请输入网关(${nowgateway}): \t"
    read gateway
    if [[ $gateway = "" ]];then
	gateway=$nowgateway
    fi
    if [[ $gateway =~ ^$ipreg$ ]]; then
        break;
    else
        echo "输入的gateway地址不合法"
    fi
done;

while true; do
    echo -en "请输入DNS地址(${nowdnsip}): \t"
    read dnsip
    if [[ $dnsip = "" ]];then
	dnsip=$nowdnsip
    fi
    if [[ $dnsip =~ ^$ipreg$ ]]; then
        break;
    else
        echo "输入的dnsip地址不合法"
    fi
done;

echo ""
echo -e "修改内容汇总"
echo -e "---------------------------------"
echo -e "IP地址: \t$ipaddr/$mask"
echo -e "网关地址: \t$gateway"
echo -e "DNS服务器地址: \t$dnsip"
echo "若是是远程连过来修改ip，请千万当心，配置错误会致使与服务器失联"

check_yes_no(){
    while true; do
        read -p "$1" yn
        if [ "$yn" = "" ]; then
            yn='Y'
        fi
        case "$yn" in
            [Yy] )
                break;;
            [Nn] )
                echo "放弃..."
                exit 1;;
            * )
                echo "请输入y或n来表明是或否";;
        esac
    done;
}

if check_yes_no "是否开始设置本机静态IP? [Y/n] ";then
	sed -ri "s/- ${ipreg}\/([0-9]$|[1-2][0-9]|3[0-2])/- ${ipaddr}\/${mask}/" $destfile
	sed -ri "s/gateway4: ${ipreg}$/gateway4: ${gateway}/" $destfile
	sed -ri "s/- ${ipreg}$/- ${dnsip}/" $destfile
	echo "设置完成，退出。"
	echo "若是你是用ssh连过来的话，可能因IP变化致使中断"
	echo "请使用新IP地址(${ipaddr})再次链接"
	# 从新应用新的配置
	sudo netplan apply
fi