linux scripting basics

rint:]: Printable characters[: Cntrl:]: Control (nonprinting) character[: Graph:]: Graphic character[: Xdigit:]: hexadecimal characterInode,block,bitmapIndex node? The Inode (index node) table contains a list of all file system files? A node (an index node) is a table item that contains information about the file (metadata), including:File type, permissions, Uid,gidNumber of links (pointing to the number of path names for this file name)The size of the file and the different timestampsData bloc

[option] file...The common options are: Options Description -d Specifies the merged delimiter, which is tab by default -s Do not merge to one line, one row for each file Work results:Experiment 10 (Data flow redirection):1. Simple Redirection2. Standard error redirection3. Use tee commands to redirect to multiple files at the same time4. Permanent Redirection5. Create an output file descriptor6. Close the file descr

as ${name:3:2}: Discard 0-2 of the array variable, only take the 3,4 array variable;Undo Array:Unset Array_NameTo delete an element in an array:Unset Array_name[index]Random variable: Can produce a set of stochastic variables between 0-32767Cases[Email protected] ~]$ echo "$RANDOM"16952[Email protected] ~]$ echo "$RANDOM"6653Five. Bash script programmingThere are three types of shell scripting:Over-programming languagesScripting Class programming languageExplanatory languageWhere the

Linux Operating System BasicsThe Linux operating system was developed in a cathedral-style and market-style way, when people were dissatisfied with the practice of monopoly charging of the UNIX operating system in commercial companies, so people modified and improved the open source code, and eventually Linux was born, Personally, it is the triumph of open source

Chapter I overview 1.1 prefaceThis chapter discusses the concept of a system, a more profound understanding of computer systems from a hardware and operating system perspective, and a quick tour of the services provided by Linux systems.1.2 System composed of 1.3 operating systems and applications Operating system This word has two meanings, sometimes refers to the kernel, sometimes refers to the combination of kernel and system tool software

How to view file permissionsls Command detailedroot user and file security controlWhat is root userUser CategoryFile Operation Permissionscharacter representation of file operation permissionsChownchgrpuse symbolic notation to set permissions on a file or directoryfeatures of the chmod commandthe-r option of the chmod commandWhat is notation notation3 parts of a permission stateexample of symbolic notationset permissions on a file or directory using numeric notationWhat is digital notationthe nu

-Specific environment variables ~/.bash_profile Login Shell User-specific environment variables ~/.bashrc All interactive shells User-specific aliases, shell features, and shell options /etc/bashrc All interactive shells Common aliases, shell features, and shell options (v) Exit login Shell~/.bash_logout is called when the user logs off, which is rarely used. Some people use it to clean up ~/.bash_history files

Linux Basics Introductory Course: HTTPS://WWW.SHIYANLOU.COM/COURSES/1A very good Linux basic course, refined, concise! Recommended!Course Content: 1th Introduction to Linux System https://www.shiyanlou.com/courses/1/labs/1/document section 2nd Basic concepts and Operation https:// www.shiyanlou.com/courses/1/labs/2/doc

The basics and management of Linux applications introduces Linux fundamentals and management, including Linux installation, Linux GUI, Linux applications, Linux character interface,

Article Title: linux classic question-basics. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. 0001 Modify host name In vi/etc/sysconfig/network, change the HOSTNAME line to HOSTNAME

char type occupies 1 bytes and the int is 4 bytes, so the output is 5?The answer is in the negative. You can try it yourself and the output is 8.Why is that? This is because the compiler optimizes the storage of the structure in order to keep the program running faster, reducing the instruction cycle of CPU read data. In fact, the first Char member, although originally only 1 bytes, actually takes up 4 bytes, so that the address of the second int member can be divisible by 4. So the actual cons

-posts55sshd #ssh守护进程S80postfixS90crond #日常计划任务S99local ================================================================== 5 , User the custom startup item configuration file runs /etc/rc.localThe path in #centos6.5 is/etc/rc.local#此配置文件可以自定义你希望开机执行的命令及脚本==================================================================[[email protected] ~]# cat/etc/rc.local#!/bin/ SH #这里的含义是使用bash来当作命令解释器 # # This script would be executed *after* all the other init scripts.# you can put your own ini Tializat

Get help with the use of commandsInternal command:Help COMMAND[[Email protected] etc]# type cdCD is a shell builtin[[email protected] etc]# Help CDCD:CD [-l|-p] [dir]Change the shell working directory.External command:COMMAND--help[Email protected] etc]# type mkdirmkdir Is/bin/mkdir[Email protected] etc]# mkdir--helpUsage: mkdir [options] ... Directory...Creates a directory if the specified directory does not exist.Command manual: ManualInfo COMMANDWhatis COMMANDMans COMMANDMans:Name: command na

1.ls-a command will list all contents (. cache,controller.py) in the current directory;In 2..cache . Indicates that the file is a hidden file; the suffix py in controller.py represents a Python script;3.vi . Profile, which is a hidden file in which the text content # indicates that the line content is commented;4.00 * * * * * sh/root/refreshbondgoods/run.sh >> Log.log, the run.sh script is executed every 3 o'clock in the morning, the log is automatically entered into the Log.log file; (for cront

Edit compiled multiplication table under Linux print out (Java Basics exercise)[Email protected] chengxu]# VI Test.javapublic class test{public static void Main (String args[]) {for (int i=0;ifor (int J =1;jSystem.out.print (j+ "*" +i+ "=" +i*j+ "");}System.out.println ();}}}[Email protected] chengxu]# Javac Test.java[[Email protected] chengxu]# java test1*1=11*2=2 2*2=41*3=3 2*3=6 3*3=91*4=4 2*4=8 3*4=12 4

Linux Basics (iv)Through the previous knowledge of learning, to learn now sell it!1. Title: Cluster construction1.1, the deployment of Nginx reverse proxy three Web services, scheduling algorithm using weighted polling;1.2, all Web services use shared storage NFS, to ensure that all the web has read and write permissions to ensure data consistency;How does this come true?Let's start by introducing Nginx,ngi

/** 5.4 Shell Basics (bash) */1.bash Introduction2.bash commandFormat: [Shell commands] [options] [parameters]Example: [[email protected] ~]#Root: User identityServer: Host Name~: Where the file is located#: PromptOnly root (super user) prompt is #The user's prompt for other identities is $Example 2:[[email protected] ~]# ls-l/rootLS: Displays the contents of the directory;-l: long list table; root is the parameter3. Common Control key combinationsCtr

Linux Basics---Scheduled tasksScheduled TasksThe 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 times the scheduled task is executed in the future, it is divided into one-time scheduled tasks and recurring scheduled tasks.A one-time s

Command-line Basics some nouns "Graphical Interface" "Command Line" Terminal "shell" "bash" Installation use Windws: Install git, open Gitbash Linux Open Terminal MAC Open Terminal Basic command View current full pathpwdView files in the current directory# 不包括隐藏文件ls# 查看当前目录下所有文件(包括隐藏文件)ls -a# 查看当前目录下所有文件(包括隐藏文件)的详细信息ls -alSwitch directoriescd /c/projectcd

1th Shell Basics 1.1 What is a shellThe shell is a command interpreter, which at the outermost of the operating system, is responsible for directly talking to the user, explaining the user's input to the operating system, and processing the output of a wide variety of operating systems, returning the output screen to the user.1.1.1 Shell Dialog modeInteractive way: From the keyboard input command, through the resolution of the/bin/bash, you can immedi