子网掩码shell脚本进制转换

#!/bin/bash
netMask=$1
##maskdigits
maskdigits(){
a=$(echo "$1" | awk -F "." '{print $1" "$2" "$3" "$4}')
for num in $a;
do
while [ $num != 0 ];do
  echo -n $(($num%2)) >> /tmp/num;
  num=$(($num/2));
done
done
echo $(grep -o "1" /tmp/num | wc -l)
rm -rf /tmp/num
}

maskNum=`echo ${#netMask}`
if [ $maskNum != 2 ]; then
	netMask=`maskdigits "$netMask"`
fi

echo $netMask

[root@prod soft]# chmod +x 2.sh 
[root@prod soft]# 
[root@prod soft]# 
[root@prod soft]# ./2.sh 255.255.255.0
24