aachyee

#!/bin/bash

# cf. https://www.skyarch.net/blog/?p=7423
ip2dec() {
  local IFS=.
  local C=($1)
  printf "%s\n" $(( (${C[0]} << 24) | (${C[1]} << 16) | (${C[2]} << 8) | ${C[3]} ))
}

mask2dec() {

aachyee

#/bin/sh
set -eu

ip2dec () {
  local ip="$1"

  if test -z "$ip"; then
    printf "Argument required" 1>&2
    return 1
  fi

aachyee

#!/bin/bash

ip2dec () {
    local a b c d ip=$@
    IFS=. read -r a b c d <<< "$ip"
    printf '%d\n' "$((a * 256 ** 3 + b * 256 ** 2 + c * 256 + d))"
}

die () {
	echo $1

aachyee

#!/bin/bash

_err() {
  printf "$(date +'%Y-%m-%dT%H:%M:%S%z') [ERROR] $@" >&2
}

_usage() {
  _err "Usage: $(basename $0) {$(sed "s/ () /|/g; s/ ()$//g;" <<< $(declare -f | egrep "^[[:alpha:]][[:graph:]]+[[:space:]]\(\)"))} \$IPADDR/\$PREFIX\n"
}

aachyee

#!/bin/bash

# src: https://stackoverflow.com/questions/20762575/explanation-of-convertor-of-cidr-to-netmask-in-linux-shell-netmask2cdir-and-cdir

mask2cidr ()
{
   # Assumes there's no "255." after a non-255 byte in the mask
   local x=${1##*255.}
   set -- 0^^^128^192^224^240^248^252^254^ $(( (${#1} - ${#x})*2 )) ${x%%.*}
   x=${1%%$3*}

aachyee

#!/bin/bash

# By Frank Danielson @ Bold Apps

IPS=(`ifconfig | grep "inet addr:" | awk -F: '{ print $2 }' | awk '{ print $1 }'`)
MASKS=(`ifconfig | grep "Mask:" | awk -F: '{ print $4 }'`)
BITS=()
i=0

mask2cidr() {

aachyee

$ ip2decimal 192.168.0.1
3232235521
$ decimal2ip 3232235521
192.168.0.1
$ 
$ ip2decimal 255.255.255.0
4294967040
$ cidr2decimal 24
4294967040