Linux Shell Programming Basics First, Shell introduction

Shell Introduction

The shell is in the outer layer of the kernel, which is responsible for receiving commands entered by the user, then interprets the command as kernel can understand it, then executes it by kernel, and returns the result back to the default output perimeter. The shell is a command interpreter and also a program language. There are many kinds of shells, and in many Linux distributions the standard shell is bash and is the main object of our learning.

First Program

Example: hello.sh

#!/bin/bash

Echo ' Hello world '

Before executing, give execution permission:

chmod +x hello.sh

Perform:

./hello.sh

Output:

Hello World

So the first shell script runs successfully.