Linux Simple Introduction

Linux is a free-to-use and free-to-propagate Unix-like operating system, a POSIX and Unix-based multiuser, multitasking, multi-threaded and multi-CPU operating system.

The basic idea of Linux is two points, 1. Everything is a document ; 2. each software has a definite purpose .

Linux directory structure

/root: This directory is a system administrator, also known as the super-privileged user home directory;

/bin: This directory holds frequently used commands;

/sbin:s is the meaning of super user, which is stored in the system administrator used by the System management program;

/boot: This directory holds the core files when Linux is started, including some connection files and images;

/dev:D evice (device), which holds the external device of Linux and accesses the device as if it were a file

/etc: all the configuration files and subdirectories required for system management;

/home: The user's main directory, each user in Linux has a directory of their own, the general directory name is named after the user account--/home/username

/var: the directory is stocked with things that are constantly expanding, and we are accustomed to placing directories that are often modified in this directory. Includes various log files.

/lib: Storage of the system's most basic dynamic connection shared library, similar to the DLL files in Windows, almost all applications need to use these shared libraries;

/USER: Many of the users ' applications and files are stored in this directory, the program Files directory under Windows

/user/bin: Applications used by system users

/user/sbin: The more advanced hypervisor and system daemon used by super users

/USER/SRC: Default drop directory for kernel source code

/tmp: The directory used to store temporary files

/media:linux system will automatically identify some devices, such as USB flash drive, optical drive, etc., when identified, Linux will attach the identified device to this directory.

/lost+found: Default is empty, non-normal shutdown, will hold some files

/MNT: The system provides this directory for users to temporarily mount other file systems, we can mount the CD-ROM drive on the/mnt/, and then enter the directory to view the contents of the CD-ROM

/srv: This directory holds data that needs to be extracted after some services are started

/run: The inside of the thing is the system needs to run, can not be deleted casually. But the reboot should be abandoned. Rebuild next time the system is running

Linux

File properties:

[Email protected]/]$ ls-llrwxrwxrwx.   1 root root    7 March  20:47 Bin--Usr/bin
Dr-xr-xr-x. 5 root root 4096 March 21:59 boot

• [ D ] is the directory
• [ - ] is the document;
• [ l ] is indicated as a linked document (link file);
• [ b ] is indicated as the device file inside the storage interface device (can be random access device)-block equipment;
• [ C ] is indicated as a serial port device inside the appliance file, such as a keyboard, mouse (one-time reading device).
• [P] indicates that the pipe file
• [s] indicates the socket file

[R] stands for readable (read), [W] for writable (write), [x] for executable (execute), three permissions for the same position, and [-] instead if no permissions

Master: File Owner

Group: In Linux systems, users are categorized by group, and one user belongs to one or more groups

Users other than the file owner can be divided into the same group of users and other users as the file owner, and for the root user, the file's permissions do not work for them in general.

Simple commands and symbolic meanings:

Shutdown: Shutdown

Restart: reboot

Administrator symbol: #

Normal User: $

CD ~: Back

CD-: Toggle

Man command name: Ask for help

WHOAMI: Displays the active user who is currently logged on

./: Current directory

.//: The parent directory of the current directory

History: Command Histories

Path completion: Use the TAB key, press an auto-completion, and then press the list once

Linux Simple Introduction