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The main content of this article is to explain the basics of Linux. Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn the basic knowledge of Linux.

1. Computer composition.

CPU,: arithmetic unit, controller, register, cache

Memory: memory (Random Access Memory)

Input:disk,adapter,keyboard,mouse

Output:disk,adapter,display

2. Kernel (kernel)

The first layer of software extension based on hardware provides the most basic functions of the operating system:

Drive the underlying hardware

Abstract the underlying resource (interface) for the program to call

Manage all kinds of running programs, allocate limited resources, and ensure that each program is safe (spoofing program, simulating all resources to be called at any time)

Complete OS: kernel+ app

OS in the narrow sense: kernel

OS interface:

GUI:Graphic User Interface

CLI: Command Line Inerface

(linux's desktop is just one of its applications)

The glorious history of the kernel is as wonderful as that of quantum physics:

Multics (Multiplexed Information and Computing Service):

Jointly developed by Bell Labs, Massachusetts Institute of Technology and General Electric in 1964, its purpose is to develop an operating system for multiuser and multitasking installed on mainframes.

Ken Thompson (later known as the father of UNIX), porting the program of "Space Travel" to an idle PDP-7 (host of Digital)

In 1973, Ken Thompson and Dennis Ritchie rewrote the third edition kernel of Unix in C language.

With the agreement of "for teaching purposes only", the fifth edition of Unix was provided to universities for teaching purposes, and became an example textbook in operating system courses at that time.

Since the V7 version of Unix in 1979, the Unix license forbids universities from using Unix source code, including learning in lectures;-foreshadowing

Berkeley: BSD Unix

AT&T: System V

SUN: solaris

IBM: AIX

HP: HP-UX

Unix-like operating system

1990 minix

1991 Linus Benedict Torvalds (his father is a communist) Linux was born, complying with GPL, its appearance provided the kernel for the GNU organization, and GNU provided a lot of APP for Linux.

With the maturity of TCP/IP and the application of http, linux is rooted in the Internet. In the following years, the network broke out and the open source linux developed rapidly.

Larry Wall devout Christians developed patch, the coordinated development of the Internet

Disadvantages:

App developed by super powerful people is usually not suitable for desktop terminals, but it can also be done beautifully.

At first, open source was considered unstable (the compilation environment was inconsistent and often went wrong), and the non-commercial characteristics (all said that IOS was stable, all said Android), this phenomenon gradually disappeared after the development of mobile Internet.

3. Common Linux releases, the connections and differences between different distributions.

Why are there different versions?

Different versions are derived from inconsistent compilation environments, which need to be maintained by the provider. Does adding different app make a difference?

A typical Linux distribution includes the Linux kernel, some GNU libraries and tools, command-line shell, an X Window system with a graphical interface, and the corresponding desktop environment.

POSIX: Portable Operating System Interface Portable operating system Interface

The POSIX standard defines the interface standard that the operating system should provide for applications, and programs written for an POSIX-compatible operating system should be compiled and executed on any other POSIX operating system, even from another vendor.

The object code compiled by ABI:Application Binary Interface runs without modification on systems that use ABI compatibility.

Common linux distributions:

Debian: non-commercial, but requires technology

Unbutu (human nature)-desktop mint

Knopix---- security system

Slackware: KISS (Keep It Simple Stupid) principle

Suse (Commercial)

OpenSuse: very popular in Europe

SLES:SUSE Linux Enterprise Server

Redhat:

After Redhat9.0

RHEL: Red Hat Enterprise Linux Business

Provide source code, do not provide compilation, you have to pay to provide services, such as patch upgrades or consulting services. (the value of this patch will be known by doing offensive and defensive drills.)

Red hat's attitude towards this centos distribution is: "We are not really opposed to this distribution. The users who really pay us pay attention not to the system itself, but to the business services we provide."

CentOS:

RHEL has always provided a way to distribute the source code, and CentOS is to recompile the source code released by RHEL to form a usable binary version.

CentOS does not provide commercial support to users and certainly does not bear any commercial responsibility (non-commercial characteristics)

Fedora: built and maintained by global community enthusiasts, Red Hat is positioned as a testing ground for new technologies. Applications in the personal field.

Gentoo:Linux the world's youngest distribution, Portage technology, software package management system.

Kali: comes with a variety of penetration tools

LFS: Linux from Scratch; build Linux yourself

Version number:

Major, minor, release

Linux kernel; 0.99; 2.2; 2.4; 2.6; 3.0; 4.0

Versions of each release:

RHEL: 5.x 6.x 7.x

Rpm,yum,dnf

Debian: 8.x

Dkpg, apt-get

OpenSuse: 13.x

Rpm,zypper

4. Common open source protocols (GPL,LGPL, BSD,Apache, etc.)

GNU: Richard Stallman; is not Unix

Free meaning: free learning and modification; free use; free distribution; free creation of derivative version

FSF was created in 1985, and a large number of heavyweight app joined. The kernel of the important component operating system (called HURD) was not implemented. At the beginning, we could only use the Unix kernel until we met linux.

X-window gcc (GUN C Complier--- > GNU Compiler Collection) VI (visual interface), many app are very powerful

FSF: free software Foundation Free Software Foundation, providing technical, legal and financial support for the NU project

GPL:General Public Licence Open Source Agreement

1) require the software to be released in the form of source code, and stipulate that any user can copy or distribute the software to other users in the form of source code.

2) if the user's software uses part of any software protected by GPL, the software inherits GPL software and therefore becomes GPL software, which means that the source code must be distributed with the application.

3) GPL does not exclude the commercial packaging and distribution of free software, nor does it restrict the packaging and distribution of other non-free software on the basis of free software.

The venom of the old venom front-- > Nancy Ren-- > soft hedgehog armour-- > Yang Kang-- > Peng Lianhu (this example is not good).

LGPL: GNU Lesser General Public License; GNU wide General Public license, similar to BSD and Apache in leniency

BSD: Berkeley Software Distribution Berkeley software distribution

1) if the re-released product contains the source code, the BSD protocol from the original code must be included in the source code

2) if only the binary class library / software is released, the BSD protocol from the original code needs to be included in the documentation and copyright notice of the class library / software.

3) the author / organization name of the open source code and the name of the original product cannot be used for marketing.

Apache: protocol adopted by the non-profit open source organization Apache

5. Linux's philosophical thought.

1) everything is a document

Open (); read (); write (); create (); close (); delete ()

2) the goal is realized by a combination of programs with many single functions, and a program only does one thing.

3) avoid dealing with users as much as possible: automate tasks by programming

4) use a text file to save configuration information

6. Linux directory structure and directory structure naming regulations

Structure: inverted tree structure directory + file

File naming: case sensitive

You can use any character except the slash (/)

Files that begin with a period are hidden files

Cannot exceed 255 characters

Path: absolute path / PATH/basename

Relative path. / basename

At this point, I believe you have a deeper understanding of the "basic knowledge explanation of Linux". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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