shell随机数比较

 #!/bin/bash
 a=$(expr $RANDOM % )   #生成一到一百的随机数
 echo $a   #打印随机数
 b=
 while true
 do
         let b++
         echo "比较了第$b次!"
         read -p "请输入一个1-100的随机数数: " num
         if [ $num -gt  ]; then
                 echo "输入错误!请重新输入!"
                 continue
         elif [ $num -le  ]; then
                 if [ $num -lt $a ]; then
                         echo "sorry,小了"
                 elif [ $num  -gt $a ]; then
                         echo "sorry,大了"
                 elif [ $num -eq $a ]; then
                         echo "恭喜,俩个数相等,获得大奖"
                         break
                 fi
         fi
 done