shell脚本函数传参

末蓝、 2022-01-14 04:55 358阅读 0赞

函数可以提高代码复用，在python、java中比较常见。  
shell脚本也有函数，可以将一组命令集或语句形成一个可用代码块。

#### 定义格式 ####

函数名(){
        command1
        command2
        ...
        commandN
        [ return value ]
    }

#### 函数返回值 ####

可以显示增加return语句；如果不加，则将最后一条命令运行结果作为返回值（一般为0，如果执行失败则返回错误代码）。  
**return后跟数值（0-255）**

#! /bin/bash
    
    function test(){
            echo "The first param is $1"
            return 111
    }
    
    test 1
    echo "The return of test is $?"

运行结果：

[root@master ~]# sh test_function.sh 
    The first param is 1
    The return of test is 111

#### Shell函数传参 ####

在Shell中，调用函数时可以向其传递参数。在函数体内部，通过 $n 的形式来获取参数的值，例如，$1表示第一个参数，$2表示第二个参数…即使用位置参数来实现参数传递。

#! /bin/bash
    
    function test(){
            echo "The first param is $1"
            echo "The second param is $2"
            echo "The third param is $3"
            echo "The forth param is $4"
            echo "The fifth param is $5"
            echo "The sixth param is $6"
            echo "The seventh param is $7"
            echo "The eigth param is $8"
            echo "The ninth param is $9"
            echo "The tength param is $10"
            echo "The 11th param is $11"
            return 111
    }
    
    test 1 2 3 4 5 6 7 8 9 55 54
    echo "The return of test is $?"

运行结果：  
\[root@master ~\]\# sh test\_function.sh  
The first param is 1  
The second param is 2  
The third param is 3  
The forth param is 4  
The fifth param is 5  
The sixth param is 6  
The seventh param is 7  
The eigth param is 8  
The ninth param is 9  
**The tength param is 10  
The 11th param is 11**

**注意，$10 不能获取第十个参数，如上结果中$10，打印结果为10。  
获取第十个参数需要$\{10\}。**

正确姿势，当n>=10时，需要使用$\{n\}来获取参数：

#! /bin/bash
    
    function test(){
            echo "The first param is $1"
            echo "The second param is $2"
            echo "The third param is $3"
            echo "The forth param is $4"
            echo "The fifth param is $5"
            echo "The sixth param is $6"
            echo "The seventh param is $7"
            echo "The eigth param is $8"
            echo "The ninth param is $9"
        	echo "The tength param is ${10}"
        	echo "The 11th param is ${11}"
            return 111
    }
    
    test 1 2 3 4 5 6 7 8 9 55 54
    echo "The return of test is $?"