Application of script seven: Subnet computing

function: calculates the subnet IP range and the number of available IPs

implementation: use BC tools to calculate, please pre-install, do not check

Insufficient: the IP address and mask format are not judged

use: provide two parameters, address and mask, output format: Host number-network number [number of available IP]

Demonstrate:

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Code area:

#/bin/bash#  ly#  ------------------#  copyright 2016.04.14 lingyi   ([email protected])  QQ: 1519952564#  ------------------------------------------ ------------------#   "subnet masks  ' calculation" #将ip地址转换为二进制, 32 characters containing only 0 and 1 get_2s () {Local  i j s stayfor  ((i=1; i<=4; i++));  do stay=$ ( echo  " obase=2; ibase=10;  ' echo $1 | cut -d '. '  -f$i ' " | bc ) #地址的每个段转换为二进制应为八位数, the number of digits on the left side plus" 0 "complement [[ ${#stay} -ne 8 ]  && { for  ((j=1; j<=8-l; j++));  do stay= "0${stay}";  Done; }s=${s} $staydoneecho   $s} #将一个32个只包含0和1的字符转换为十进制, and the format of the IP address get_10s () {local n t# Truncates the string by one field per eight bits and converts to decimal for n in 0 8 16 24; do t=${t}.$ ( echo  "Obase=10; ibase=2;${1:n:8}" |bc ) doneecho  $T  | sed  ' s/^.//'} #将地址和掩码转换为二进制字符串ip_2s =$ ( get_2s $1 ) mask_2s=$ ( get_2s $2 ) # Compare the binary of the address and mask, get the binary string for the host number for ((i=0; i<32; i++));  doa=${ip_2s:i:1}b=${mask_2s:i:1} #模拟二进制的与操作 [[ ${b} -eq 1 ]] && comp_2s=${comp_2s} $a  | |  comp_2s=${comp_2s}0done# calculate the number of "0" in the mask N, the number of available IPs is  2 N minus 2 (host number and network number is not available) sum_1=$ ( echo ${mask_2s } | grep -o  ' 1 '  | wc -l ) useful_ip_sum=$ (( $ ( echo  2^$ ((32-sum_1)) " | bc "  -2 ) #网络号即将主机号的主机位全置为1broadcast_2s =${ip_2s:0:sum_1}$ (for  ( i=0; i<32-sum_1; i++); do echo -n  ' 1 ';  done) #将二进制转换为十进制 and output echo in address format  -e  "\033[1;34m$ (get_10s  $comp _2s)  - $ (get_10s  $broadcast _2s)  [ $ Useful_ip_sum ]\033[0m "

This article is from the "retrograde person" blog, please be sure to keep this source http://lingyi.blog.51cto.com/2837715/1763902

Application of script seven: Subnet computing