Programming Basics for Shell scripts

Program: Instruction + data

Program Programming Style:

Program: command-centric, data-serving instruction

Object type: Data-centric, instruction serves data

Shell program: Provides programming capabilities to interpret execution

How to handle the programming logic:

Sequential execution

Loop execution

Select Execute

Shell programming: procedural, interpreting execution

The basic structure of the programming language:

A combination of various system commands

Data storage: variables, arrays

Expression: A + b

Statement: If

Shell script:

A text file that contains some commands or declarations and conforms to a certain format

Format requirements: First line shebang mechanism

#! /Bin/bash

#！ /usr/bin/python

#!/usr/bin/perl

The uses of shell scripts are:

Automating common commands

Perform system administration and troubleshooting

Create a simple application

Working with text or files

Create a shell script

First step: Use a text editor to create a text file

The first line must include the shell declaration sequence: #!

#！ /bin/bash

Add Comment

Comments start with #

Step two: Run the script

Give execute permission to specify the absolute or relative path of the script on the command line

Run the interpreter directly and run the script as a parameter of the interpreter program

Scripting specifications

1. The first line is generally the language used for the call

2. Program name, avoid changing the file name to not find the correct file

3. Version number

4. Time after the change

5. Related information of the author

6. The role of the procedure, and matters needing attention

7. Finally, a brief description of the updates for each version

Basic structure of the script

#！ Shebang

CONFIGURATION Vriables

Function_definitions

Main_code

Programming Basics for Shell scripts