Linux shell 网络掩码地址转CIDR

例子：

./1.sh 255.255.255.0

./1.sh 255.255.255.128

./1.sh 255.255.0.0

源实现：

#!/bin/bash

netmask_to_cidr() {
    local IFS
    local -a octets
    local i=0
    local cidr=0

    IFS='.' read -r -a octets <<< "$1"
    for octet in "${octets[@]}"; do
        while [ $octet -gt 0 ]; do
            cidr=$((cidr + (octet & 1)))
            octet=$((octet >> 1))
        done
    done
    echo "$cidr"
}

# 将点分十进制格式的子网掩码转换为CIDR格式
netmask=$1
cidr=$(netmask_to_cidr $netmask)
echo "子网掩码 $netmask 转换为CIDR格式为: /$cidr"