shell脚本，计算输入给定的数，判断最大值，最小值，总和？

[root@localhost ~]# cat five.sh
#!/bin/bash
#任意输入5个数，判断最大值，最小值，总和

s=
read -p "please input:" num

s=$(($s+$num))
max=$num
min=$num
for i in `seq `
do
      read -p "please input:" num
      s=$(($s+$num))

      if [ $num -le $min ];then
        min=$num
      fi

      if [ $num -ge $max ];then
         max=$num
      fi

done
echo sum:$s max:$max min:$min
[root@localhost ~]# bash five.sh
please input:
please input:
please input:
please input:
please input:
sum: max: min:0

[root@localhost ~]# cat 2five.sh
#!/bin/bash
#任意输入3个数，判断最大值，最小值，总和

s=
n=
for i in `seq `
do
      read -p "please input:" num
       expr  ${num}  +    >/dev/null  >&
       if   [   $?   -eq      ];then
       echo   "${num}   is   a   number!"
       else
       echo   "${num}   is   not   a   number!"
       exit
        fi   

      s=$(($s+$num))
      [ $n -eq  ] && max=$num && min=$num
      n=$(($n+))

      if [ $num -le $min ];then
        min=$num
      fi

      if [ $num -ge $max ];then
         max=$num
      fi

done
echo sum:$s max:$max min:$min n:$n
[root@localhost ~]# bash 2five.sh
please input:
   is   a   number!
please input:
   is   a   number!
please input:
   is   a   number!
sum: max: min: n:
[root@localhost ~]#