Shell添加指定数量的用户

#!/bin/bash
read -p "please input user name:" -t 30 name
read -p "please input the number of users:" -t 30 num
read -p "please input the password of users:" -t 30 pass
if [ ! -z "$name" -a ! -z "$num" -a ! -z "$pass" ]
    then
    y=$(echo $num|sed 's/[0-9]//g')
    if [ -z "$y" ]
        then
        for((i=1;i<=$num;i=i+1))
        do
            /usr/sbin/useradd $name$i &>/dev/null
            echo $pass |/usr/bin/passwd --stdin $name$i &>/dev/null
        done
    fi
fi