Linux details, linux details

Linux details, linux details
Linux1

Linux is not Unix

The Linux kernel was originally written by Linus Torvalds, a Finnish student, at the University of Helsinki for personal interests.

Linux is a free and free-to-use Unix-like operating system. It is a POSIX and UNIX-based multi-user, multi-task, multi-thread and multi-CPU operating system.

Linux can run the main UNIX tool software, applications and network protocols. It supports 32-bit and 64-bit hardware. Linux inherits the network-centric Unix design philosophy and is a stable multi-user network operating system.

Comparison between windows and linux

Comparison item	Windows	Linux
Interface	Unified interface, shell fixed all Windows program menus are almost the same, and the shortcut keys are almost the same	The graphic interface style varies with the release version, and may be incompatible with each other. The GNU/Linux terminal is inherited from UNIX, and the basic commands and operation methods are almost the same.
Driver	A wide range of drivers and frequent version updates. The default installer generally contains the hardware drivers that are popular when the version is released, and the new hardware drivers subsequently come out depend on the hardware vendor. For some old hardware, it is sometimes difficult to support a driver without the original configuration. In addition, sometimes the hardware vendor does not provide the required version of the driver for Windows, it will be a headache.	Developed by volunteers and released by the Linux core development team, many hardware vendors do not provide drivers based on copyright considerations. Although most do not require manual installation, installation is relatively complex, this makes it impossible for new users to face driver issues (whether the driver exists and how to install it. However, in the open-source development mode, many old hardware, although difficult to support in Windows, can easily find the driver. Hardware vendors such as HP, Intel, and AMD gradually support open-source drivers to varying degrees, and the problem is being mitigated.
Learning	Easy to use. The graphical interface is very advantageous for users who have no background knowledge about computers.	GUI is easy to use and easy to get started. Text interface, you need to learn to master.
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Use	The system structure is complex and frequently changed, and knowledge and skills are quickly eliminated, making it difficult to study in depth.	The system structure is simple, stable, and has good inheritance of knowledge and skills. It is relatively easy to learn in depth.
Software	Each specific function may be supported by commercial software and requires the corresponding authorization.	Most of the software can be freely obtained, and there are fewer options for software with the same function.

Install Linux

Centos6.4

Installation Process

Linux Startup

Process

Startup Process

Kernel boot

Run init

System initialization

Establish a terminal

Logon System

Linux directory structure

Linux directory explanation

Directory Name	Explanation
/Bin	Is short for Binary. This directory stores frequently-used commands.
/Boot	Some core files used to start Linux are stored here, including some connection files and image files.
/Dev	Yes	Device)
/Etc	This directory stores the configuration files and subdirectories required by all systems for management.
/Home	Sub-directory of a user. in Linux, each user has its own directory. Generally, the directory name is named after the user's account.
/Lib	This directory stores the most basic dynamic link shared libraries in the system. Its function is similar to the DLL files in Windows. Almost all applications need to use these shared libraries.
/Lost + fond	This directory is usually empty. When the system is shut down illegally, some files are stored here.
/Media	The Linux system will automatically identify some devices, such as USB flash drives and optical drives. After recognition, Linux will mount the identified devices to this directory.
/Mnt	The system provides this directory for users to temporarily Mount other file systems. We can mount the optical drive to/mnt/And then view the content of this optical drive in this directory.
/Opt	This is the directory for additional software installation on the host. An ORACLE database can be placed under this directory, which is empty by default.
/Proc	This directory is a virtual directory, which is the ing of system memory. We can directly access this directory to obtain system information. The contents of this directory are not on the hard disk, but in the memory. We can also directly modify some files in it. For example, we can use the following command to shield the Ping command of the host, preventing others from pinging your machine
/Root	This directory is the user home directory of the system administrator, also known as the super authorizer.
/Sbin	S indicates the Super User, which stores the system management program used by the system administrator.
/Selinux	This directory is unique to Redhat/CentOS. Selinux is a security mechanism similar to Windows Firewall, but this mechanism is complicated. This directory stores selinux-related files.
/Srv	This directory stores the data to be extracted after the service is started.
/Sys	This is a big change in the Linux 2.6 kernel. A new file system sysfs is installed in this directory. The system integrates the information of the following three file systems: the proc file system for process information, the devfs File System for the device, and the devpts File System for the Pseudo Terminal. This file system is an intuitive reflection of the kernel Device Tree. When a kernel object is created, the corresponding files and directories are also created in the kernel sub-Object System.
/Tmp	This directory is used to store some temporary files.
/Usr	This is a very important directory where many of your applications and files are stored, similar to the program files directory in Windows.
/Usr/bin	Applications used by system users
/Usr/sbin	Advanced hyperuser management programs and system daemon
/Usr/src	Default directory for kernel source code placement
/Var	This directory stores constantly expanding things. We are used to placing frequently modified directories under this directory, including various log files.