interactive shell script tutorial

. Second, Bash provides an extended select for interactive applications that users can choose from a different set of values. The syntax is as follows: Select Var in ...; Do break ; Done For example, the output of the following program is: #!/bin/bash echo "Your choice?" Select Var in "a" "B" "C"; Do-break-done echo $var ---------------------------- Your choice? 1) a 2) b 3) C Third, a custom function can also be used in

As already mentioned, variable names can only contain numbers, letters, and underscores, because some variables that contain other characters have special meanings, and such variables are called special variables.For example, $ represents the ID of the current shell process, the PID, as shown in the following code: $echo $$ Run results29949 List of special variables variables meaning $ F

Create a script Linux has many different shells, but we usually use Bash (Bourne again shell) for shell programming, because Bash is free and easy to use. So in this article, all the scripts provided by the author use Bash (but in most cases, these scripts can also be run in Bash's big sister, Bourne shell ).Like othe

Knowledge before learning shell scripts1) Record command historyThe commands we've knocked on, Linux will be recorded, and presets can record 1000 historical commands. These commands are saved in the. bash_history file in the user's home directory. One thing you need to know is that commands that run in the current shell are saved to the. bash_history file only when the user exits the current

Shell script programming and file system RepairGuideThe Linux Foundation has initiated the LFCS certification (Linux Foundation Certification System Administrator) Linux Foundation Certified Sysadmin, which is a brand new certification system, the certification aims to enable people from all over the world to take the basic management operations of medium-level Linux systems. The certification includes: mai

1. Linux script compiling Basics 1.1 Basic syntax Introduction Start with 1.1.1 The program must start with the following line (must begin with the first line of the file ): #! /Bin/sh Symbol #! The parameter used to tell the system that the program is used to execute the file. In this example, we use/bin/sh to execute the program. When editing a script, you must make it executable if you want to execute it

Preliminary understanding of shell script Programming Programming is the process of writing program source code using human natural language or machine language. This is what we all know, because IT, after all, has programmed the Student Achievement Management System and the library management system. And so on.Programming in order to allow users to complete some tasks in non-

one row and one row for execution, the main components contained in the script include comments, commands, shell variables, and structure control statements. 2. note: The comments are used to explain and describe the script, add the symbol # before the comment line, so that shell will not explain the line when executi

1. When a string is used more frequently in a script and the string length is long, you should use a variable instead2. Variables are essential when using conditional statements3. When referencing the result of a command, replace it with a variable4. Variables are also necessary when writing scripts for user interactionBuilt-in variables, $ ...Mathematical Operation a=1;b=2; c=$ (($a + $b)) or $[$a + $b]Test Sample: Write an

a child shell process;Exercise 1: Write a script that implements the following functions;(1) Display all files or directories in the/etc directory that begin with uppercase p or lowercase p;(2) Displays all the files or directories in the/var directory itself, and converts the lowercase letters in the displayed results to uppercase and then displays;(3) Create temporary file/tmp/myfile. XXXX;Bash configura

operating system consist of?Kernel, shell, application, file systemShell: A Bridge of command interpreter man-machine interactionTerminal--"command|Bash Shell interpreter (shell)|Kernel|HardwareWhat is a shell script?In a nutshell, save the command you want to execute in th

Tags: a preliminary understanding of shell scriptsProgramming is the process of writing program source code using human natural language or machine language. This is what we all know, because it, after all, has programmed what student performance management system, library management system. Wait a minute...Programming in order to enable users to use the computer, you can let the computer do some tasks in a non-in