算术运算

# num1=3

# num2=13

加法

# let sum=$num1+$num2

# echo $sum

16

乘法

# echo $[$num1*$num2]

39

除法

# echo $(($num2/$num1))

取余

# echo $(expr $num2 % $num1)

增强型赋值

# count=1

# let count+=1

# echo $count

2

# let count++

# echo $count

3