Linux entry fourth day--shell basics

First, shell overview

　　1. Overview

command-line interpreter　　 (shell, which is our operating interface), the computer only knows 0101 binary, we need to use the ASCII table to translate

　　The more official explanation is:

The shell is a program written in C that is a bridge for users to use Linux. The shell is both a command language and a programming language.

A Shell is an application that provides an interface through which users access the service of the operating system kernel.

　　

　　　　2.shell classification

• Bourne Shell (/usr/bin/sh or/bin/sh)
• Bourne Again Shell (/bin/bash)--Standard Shell,bash
• C Shell (/USR/BIN/CSH)
• K Shell (/usr/bin/ksh)
• Shell for Root (/sbin/sh)
• ......

Second, the script execution mode

　　Let's start with a few related commands:

1. output command :Echo

　　Example 1:

the-e option allows you to control the format by using control characters :

　　Example 2:

　　Other echo features, such as output hex, output color, etc. are not expanded here

　　First shell script

　　#! is a contract tag that tells the system what interpreter the script needs to execute, even if it uses a Shell.

The second line is a comment, followed by the script content, here is the output

Linux entry fourth day--shell basics