18. Shell Scripting (1)

Object oriented and process oriented

object-oriented ： Everything is the object , Object is the concrete of class , A class is a collection of things ,python java c# golang etc.

Process oriented ： Command centric , Data serves instruction , The problem is small , Step by step ,c shell

programing language

Low level assembly language 、 High level assembly language

Low level assembly language ： The binary 0 and 1 Sequence

High level assembly language ：

              compile ： High-level language - compiler - Machine code file - perform

              explain ： High-level language - perform - Interpreter - Machine code  

Edit logical processing

Sequential structure process 、 Branch structure process 、 Cycle structure flow

shell Basis of editing

Format requirements ： First line shebang Mechanism   ( That is, tell the script written in which language ）

1、 Create a text file using a text editor （ The first line must include shell Affirming #!）

2、 Add execute permission

3、 Run script （bash  ​ ​file.sh​​​( The script does not require execution permission ）、.\​ ​file.sh​​( Relative paths ,x jurisdiction ） \data\file.sh( Absolute path mode ,x jurisdiction ））

PATH Add path execution

Script specification

1、 first line shebang Mechanism

2、 The program name

3、 Version number

4、 Time after change

5、 Information about the author

6、 The role of the script and precautions

7、 Brief description of previous versions

Remote site execution script

Script debugging

There are three common script errors

1、 Grammar mistakes , Will cause subsequent commands not to be executed , have access to bash -n Detect errors , The number of lines prompted is not necessarily accurate

2、 Wrong command , By default, subsequent commands will also be executed , use bash -n Can't detect , have access to bash -x To observe

3、 Logic error ： Only use bash -x To observe