Linux Shell数字加

今天学习linux下的shell编程，了解到的整数相加的方法。

#!/bin/sh

let a=$1+$2

b=$[$1+$2]

((c=$1+$2))

d=`expr $1 + $2`

echo "$1+$2 = ${a}"

echo "$1+$2 = $b"

echo "$1+$2 = $c"

echo "$1+$2 = $d"

 

输入命令:./plus 1 2

输出结果:1+2 = 3

             1+2 = 3

             1+2 = 3

             1+2 = 3