shell编程语法错误

Question

num1 = 20
num2 = 20

echo $(( num1 + num2 ))
echo $(( num1 - num2 ))
echo $(( num1 * num2 ))
echo $(( num1 / num2 ))
echo $(( num1 % num2 ))

错误 ：

./practice.sh: line 53: num1: command not found
./practice.sh: line 54: num2: command not found
0
0
0
./practice.sh: line 59: num1 / num2 : division by 0 (error token is "num2 ")
./practice.sh: line 60: num1 % num2 : division by 0 (error token is "num2 ")

我缺少什么？当我尝试一些数字而不是num1内部num2回声时。我注意到它打印正确......但是，这里发生了什么......？

Answer 1

num1=20
num2=20

当我尝试从 num1 和 num2 中删除空格时。我注意到它正在工作