script if

Knowledge Point Grooming: Click the link to enter1. Shell Introduction and variables, scripting related concepts2. Bash Programming: Condition testing3. Bash Programming: arithmetic operations4. Bash Programming: If statements5. Bash Programming:

1, describe the operation principle of shell program;The shell is both the command language, the programming language, and the command interpreter.Shell scripts are typically #! The starting text file, such as "#!/bin/bash", which is called shebang,

1. Describe the operation principle of shell program (can be attached with necessary graphic instructions);Shell Summary2, summarize all the knowledge points involved in shell programming (such as: variables, grammar, command status, etc., to take

First, homework (exercise) content:1. Describe the operation principle of shell program (can be attached with necessary graphic instructions);2, summarize all the knowledge points involved in shell programming (such as: variables, grammar, command

This article explains how CentOS can surf the web, and describes how to make CentOS networked in VMware virtual machines, ideally suited to all situations where a host uses a router or dial-up Internet connection. The system used by the author is

What is a q:1 shell script and is it required?A: A shell script is a text file that contains one or more commands. As a system administrator, we often need to use multiple commands to accomplish a task, and we can add all these commands in a text

Linux front and back process switchingWhen you start a program with the shell, he often works in the foreground. For example, often with putty connection to the remote server to execute the script, if the local network is interrupted, this time the

1. If you judge some special usageIf [-Z $a] This indicates what happens when the value of variable A is emptyif [!-e file]; Then what happens when the file doesn't exist?if (($a ,==,!=,>=,$ $ does not exist, so n is empty;[Email protected] ~]# n= '

System and Management commandsUsers and Groups class commandsUsersDegree of importance: MediumDisplays all logged-on users. This command is basically consistent with the who-q.GroupsDegree of importance: MediumLists the current user and the group to

With the Nginx Web server getting more and more favor of SA, Nginx cache function already has the Web caching acceleration function that squid owns, and clears the function of specifying URL cache.In the performance, Nginx on the use of multi-core

1. Introduction to SED Sed is an online editor that processes a single line of content at a time. When processing, the currently processed rows are stored in a temporary buffer called pattern space, followed by the SED command to process the

Scheduled Tasks The so-called scheduled task is to perform one or more specific jobs (tasks) at a specific time in the future. Implementation of the job without human intervention.I. Classification of SCHEDULED TasksDepending on the number of

ObjectiveThere are three types of distributed locks:1. Database optimistic lock; 2. Redis-based distributed locks; 3. Zookeeper-based distributed locks . this blog will introduce the second way to implement distributed locks based on Redis. Although

Absrtact: I have to explain that this thing is not high-end, even look a bit bad. And with a single-threaded ~, because a few days to move, so.Environment Preparation python2.7 Passable Linux Almost the wireless card Pywifi

Scripting for Bash programming until statements and formatted hard disk partitions in Linux (10)1. Summary of circular statement structure1.1.while Statement Enter the Loop statement when the condition is metWhile condition; DoStatementDone1.2.until

1.1 Shell Script Writing specification 1.2 Variable and special variable application 1.3 Local variables and global variables 1.4 Test-piece expression ------------------------------------------------------ Background: In some complex Linux

　　　　In some complex Linux maintenance work, a lot of repetitive inputs and interactions are time-consuming and error-prone. Scripts are needed.The benefits of scripting: batch processing, automated completion of maintenance, reduction of the burden

On the use of test statements and related use rules, if only isolated use is difficult to have its application, of course, in the shell script can not exist in isolation, only with conditional statements and control statements and other uses to make

Turn from:http://blog.csdn.net/dawnstar_hoo/article/details/4043887Table of Contents1. Introduction to SED2. Addressing3. SED command4. Options5. Meta Character Set6. Example7. Scripts1. Introduction to SEDSed is an online editor that processes a

sed command file Edit Document index [hide] sed option, command, replace mark option parameter sed command sed replace mark sed meta character set SED usage instance replace operation: s command full replacement Mark G delimiter delete operation: D