使用 seq 和 math 操作 ip 地址中的最后一个八位字节以创建文件

Ubuntu 16.04 GNU bash，版本 4.3.48(1)-release (x86_64-pc-linux-gnu)

我们必须每天向服务器添加几次 ips。我发现自己根据 ip 块创建了同一文件的不同变体。

#-- 100.100.100.160/29 - Sun 04/22/18 02-38-pm
#-- -----------------------------------------
auto eth0:0
iface eth0:0 inet static
    address 100.100.100.160
    netmask 255.255.255.255

auto eth0:1
iface eth0:1 inet static
    address 100.100.100.161
    netmask 255.255.255.255

auto eth0:2
iface eth0:2 inet static
    address 100.100.100.162
    netmask 255.255.255.255

auto eth0:3
iface eth0:3 inet static
    address 100.100.100.163
    netmask 255.255.255.255

auto eth0:4
iface eth0:4 inet static
    address 100.100.100.164
    netmask 255.255.255.255

auto eth0:5
iface eth0:5 inet static
    address 100.100.100.165
    netmask 255.255.255.255

auto eth0:6
iface eth0:6 inet static
    address 100.100.100.166
    netmask 255.255.255.255

auto eth0:7
iface eth0:7 inet static
    address 99.100.100.167
    netmask 255.255.255.255

所以我想创建一个脚本让我尽可能接近那个文件，所以我写了一个脚本，这里是它的一部分......

#!/bin/bash
#
#-- bash add_ips.sh "eth0" "100.100.100.160" "255.255.255.255" "29"

wDir="/scripts/tools/ips"
ifaceFile="/etc/network/interfaces"
ipFile="${wDir}/ipFile.txt"
nic="${1}"
address="${2}"
netmask="${3}"
block="${4}"
timeStamp="$(date '+%a %D %I-%M-%P')"

if [ ! -n "$4" ]; then
   echo 'add_ips.sh nic address mask block ...';
   exit 1;
fi

#-- echo the address block on a header line
{
   echo "";
   echo "#-- IP Block ${address}/${block} - ${timeStamp}";
   echo "#-- ----------------------------------------------";
} > "$ipFile"

#-- If a 30/block
if [[ "$block" == "30" ]]; then
   start="0"
   end="3"
   for ipnum in $(seq "$start" "$end"); do
      {
         echo "auto ${nic}:${ipnum}";
         echo "iface ${nic}:${ipnum} inet static";
         echo -e "\t address ${address}";
         echo -e "\t netmask ${netmask}";
         echo "";
      } >> "$ipFile"
   done

输出接近于我正在寻找的内容，剩下要做的就是更改 IP 地址的最后一个数字。

#-- 100.100.100.160/29 - Sun 04/22/18 02-38-pm
#-- -----------------------------------------
auto eth0:0
iface eth0:0 inet static
    address 100.100.100.160
    netmask 255.255.255.255

auto eth0:1
iface eth0:1 inet static
    address 100.100.100.160
    netmask 255.255.255.255

auto eth0:2
iface eth0:2 inet static
    address 100.100.100.160
    netmask 255.255.255.255

如何在该行上添加当前循环的 $seq 值时更改 ip 地址的最后一个八位字节？

我试过这个

#-- If a 30/block
if [[ "$block" == "30" ]]; then
   start="0"
   end="3"
   for ipnum in $(seq "$start" "$end"); do
      ipaddress=$(expr "$address" + "$ipnum")
      {
         echo "auto ${nic}:${ipnum}";
         echo "iface ${nic}:${ipnum} inet static";
         echo -e "\t address ${ipaddress}";
         echo -e "\t netmask ${netmask}";
         echo "";
      } >> "$ipFile"
   done
fi

地址不是整数，所以它失败了。