basename [string / pathname] [suffix]  	（功能描述：basename命令会删掉所有的前缀包括最后一个（‘/’）字符，然后将字符串显示出来。

[atguigu@hadoop101 datas]$ basename /home/atguigu/banzhang.txt 
banzhang.txt
[atguigu@hadoop101 datas]$ basename /home/atguigu/banzhang.txt .txt
banzhang

[atguigu@hadoop101 ~]$ dirname /home/atguigu/banzhang.txt 
/home/atguigu

[ function ] funname[()]
{
	Action;
	[return int;]
}
funname

[atguigu@hadoop101 datas]$ touch fun.sh
[atguigu@hadoop101 datas]$ vim fun.sh

#!/bin/bash
function sum()
{
    s=0
    s=$[ $1 + $2 ]
    echo "$s"
}

read -p "Please input the number1: " n1;
read -p "Please input the number2: " n2;
sum $n1 $n2;

[atguigu@hadoop101 datas]$ chmod 777 fun.sh
[atguigu@hadoop101 datas]$ ./fun.sh 
Please input the number1: 2
Please input the number2: 5
7