Shell

What is 21.2 shell?The shell is a command-line interpreter that provides the user with an interface system-level program that sends a request to the Linux kernel to run the program, allowing the user to start, suspend, stop, or even write programs

Conditional judgmentIf condition 1;thenCOMMANDElif condition 2;thenCOMMANDElseCommand (:): Indicates that pass does not execute any commandFiRead user input for data judgment1 Echo-N"Enter your number:"2 Read Userinput3 Expr$userinput

1. What is a shell variableSimply put, a variable is a fixed string instead of more complex content, which may also contain variables, paths, strings, and other content. Variables are places where data is stored temporarily and data tags, the stored

The shell supports a variety of operators, including: Arithmetic operators Relational operators Boolean operator String operators File Test Operators Native bash

This script is primarily used to manually publish war packages for non-MAVEN tomcat projects,1. Upload the Test war package to the specified directory2, back up the current production code3. Automatic configuration file replacement4, the release of

8.6 Pipe symbol and job control8.7/8.8 Shell variables8.9 environment variable configuration file 8.6 Pipe symbol and job control 1. Pipe Symbol | Pass the result of the preceding command to the following commandFor example, # cat

8.10 Shell Special Symbol Cut command8.11 Sort_wc_uniq Command8.12 tee_tr_split Command8.13 Shell Special Symbol Shell Special Symbols * represents all characters for wildcards ？ is a single character is the

Shell Special Symbol _cut command概念：cut命令用来截取某一个字段格式：cut -d ‘分割字符‘ [-cf] n,这里的n是数字，该命令选项有如下几个：- d 后面跟分割字符，分割字符要用单引号括起来- c 后面接的是第几个字符- f 后面接的是第几个区块The Cut command uses the following [Email protected] do]# cat/etc/passwd

Shell IntroductionThe shell is a command interpreter that provides interaction between the user and the machineFor example, we have remote login tool, it is actually a shellThe CentOS default shell is bash (Bourne Agin Shell)·Command historyHistory

Contact Linux in the sophomore time, then fascinated by the embedded Linux, the computer replaced with Linux system, learning the basic knowledge of Linux, learning Linux commands, learning shell, bubble forum, so slowly the normal work of learning

Regular expressionsSingle character notationThe character itself . \d \d \w \w \ t \ r \ \s \s [ABC] [A-c] [0-2] [1-3a-cx-z] [^ABC] [: Upper:] [: Lower:] [: Alpha:] [: Alnum:] [:d igit:] [: xdigit:] [:p UNCT:] [email protected]\^_ ' {|} ~-][: Blank:]

变量：命名的内存空间 数据存储方式： 字符： 数值：整型，浮点型 变量：变量类型 作用： 1、数据存储格式 2、参与的运算 3、表示的数据范围 类型： 字符 数值：整型、浮点型 强类型：变量不经过强制转换，它永远是这个数据类型，不允许隐式的类型转换。 一般定义变量时必须指定类型、参与运算必须符合类型要求； 调用未声明 变量会产生错误 如 java,c# 弱类型：语言的运行时会隐式做数据类型转换。无须指定类型， 默认均为字符型；参与运算会自动进行隐式类型转换； 变量无须事先定义可直接调用

1. TopicsThere are log 1.log, part of the following:112.111.12.248 - [25/Sep/2013:16:08:31 +0800]formula-x.haotui.com "/seccode.php?update=0.5593110133088248" 200"http://formula-x.haotui.com/registerbbs.php" "Mozilla/4.0 (compatible; MSIE 6.0;

1. In most cases, UNIX system commands accept input from your terminal and send the resulting output back to your terminalThe list of REDIRECT commands is as follows:2. Output redirection: Redirects are generally implemented by inserting specific

Shell Script Summary ArraySeveral common uses of indexed arraysarray[0] array数组的第一个值array[*] array数组的所有值#array[*] array数组里数值的个数unset array[0] 删除array数组里的第一个值unset array 删除掉array整个数组Array slices: ${array[@]:num1:num2} num1:要跳过的元素个数

#!/bin/bash#Date: Writing Time 2016-11-22 15:04:12 # #date "+%y-%m-%d%h:%m:%s"#Author: author#Mail: Email [email protected]#Function: Script Introduction#Version: version V1.1#Update: Script Modification Update time6.1.1 version and Operating

Array Declaration ArrayDeclare-a Array_NameDeclare-a array_name: Associative arrayNote: The two cannot be converted to each otherArray name and subscript (index)Index: Numbering starting from 0, which is a numeric indexNote: Indexes can support the

There are times when a feature is embedded in the Java function, which is implemented by a shell script. At this point, Java support for scripting calls is required.Test environmentUbuntu16.04 I3-6100,12GBHello WorldTake a look at a basic example

A few days ago, a classmate in the group to raise an egg problem, the original question is as follows:There was a basket of eggs,One 1, just take it out.2, 2, take it, just finish it.3, 3, take it, just finish it.4 of 4, 2 left.5 of 5, 4 left.6, 6,

How can I implement real-time alarm functions through shell scripts and enterprises ?, Shell Information At work, we will have some applications running on the server online, so these applications have problems. For example, after the memory and CPU