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Bash算术运算

一、两种方式expr和let

Let是expr的简化版，更简单以及易懂。

例如：expr要求操作符两边必须空格

Expr要求乘法必须转义

二、代码

#! /bin/bash

a=`expr 2 + 3`

echo "a = $a"

b=5

c=`expr $b - 4`

echo "c = $c"

e=9

f=4

g=`expr $e /* $f`

echo "g = $g"

h=10

i=3

j=`expr $h / $i`

echo "j = $j"

k=13

l=5

m=`expr $k % $l`

echo "m = $m"

############expr

#a = 5

#c = 1

#g = 36

#j = 3

#m = 3

###########Key Point

#1.blank symbols at the left and right sides of the operation symbol

#2.escape symbol for times operation

let "n+=10"

echo "n=$n"

let "o-=$n"

echo "o=$o"

let "p=$n*3"

echo "p=$p"

let "q=$n/2"

echo "q=$q"

let "r=10%3"

echo "r=$r"

#############let

#n=10

#o=-10

#p=30

#q=5

#r=1

#############Key Point

#1. let is easier than expr