shell--练习--简易计算器

#!/bin/bash

echo "请输入第一个数："
read fir
echo "请输入运算符："
echo "1:+"
echo "2:-"
echo "3:*"
echo "4:/"
read fu
echo "请输入第二个数："
read se
if [ $fu == 1 ]
then
  echo `expr $fir + $se`
fi
if [ $fu == 2 ]
then
  echo `expr $fir - $se`
fi
if [ $fu == 3 ]
then
  echo `expr $fir * $se`
fi
if [ $fu == 4 ]
then
  echo `expr $fir / $se`
fi