Shell script (V) -- function

Catalog

One 、shell Function definition

Two 、 Format

1、 Format 1 ：

2、 Format two ：

3、 ... and 、 Function return value

  Four 、 Function arguments

  5、 ... and 、 The scope of function variable

  6、 ... and 、 recursive

1、 Factorial

 2、 Recursive directory lookup

  7、 ... and 、 Create function libraries

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One 、shell Function definition

Write command sequences together in format , It is convenient to reuse the command sequence

Two 、 Format

1、 Format 1 ：

function  Function name  {

 Command sequence 

}

2、 Format two ：

 Function name () {

 Command sequence 

}

3、 ... and 、 Function return value

• return Represents the exit function and returns an exit value , You can use $ ? The variable displays the value

• Usage principle ：

  • 1、 Take the return value as soon as the function ends , because $? Variable returns only the exit status code of the last command executed
  • 2、 Exit status code must be 0~255, When exceeded, the value will be divided by 256 Remainder

 

 

  Four 、 Function arguments

 

  5、 ... and 、 The scope of function variable

• Function in Shell In the script, only in the current Shell Effective in the environment
•  Shell Variables in scripts are globally valid by default
•   Restrict variables to functions and use local command

 

 

  6、 ... and 、 recursive

1、 Factorial

 2、 Recursive directory lookup

 

  7、 ... and 、 Create function libraries

  Put commonly used functions into a separate library script , Facilitate the use of scripts , You can directly call the functions in this library

 

 

Catalog

One 、shell Function definition

Two 、 Format

1、 Format 1 ：

2、 Format two ：

3、 ... and 、 Function return value

  Four 、 Function arguments

  5、 ... and 、 The scope of function variable

  6、 ... and 、 recursive

1、 Factorial

 2、 Recursive directory lookup

  7、 ... and 、 Create function libraries

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