[First introduction to Linux] Part 1

First introduction to Linux

1. Linux background
- - - 1.1 History of UNIX development
    - 1.2 History of UNIX development
2. Open source
3. Official website
- Linux official website
4. Current status of enterprise applications
5. Release version
6. os concept and positioning

本博客简介

Initial Linux operating system

Get to know shell commands for the first time and understand some background knowledge.

Use common Linux commands

Understand the concepts and ideas of Linux permissions, and have a deep understanding of "permissions"

A preliminary understanding of the meaning of Linux directory structure

1. Linux background

1.1 History of UNIX development

- 1968年，一些来自通用电器公司、贝尔实验室和麻省理工学院的研究人员开发了一个名叫Multics的特殊操作系统。Multics在多任务文件管理和用户连接中综合了许多新概念。

From 1969 to 1970, AT&T Bell Labs researchers Ken Tompson and Dennis
Ritchie developed the UINX system based on many Multics features. It runs on a minicomputer and meets the system's requirements for a scientific research environment. From its inception, UNIX has been a valuable, efficient, multi-user and multi-tasking operating system.
UNIX began by meeting individual design needs and gradually grew into a standard software product supported by many different developers.
The first version of UNIX was provided free of charge to computer science departments at many well-known universities.
In 1972, Bell Labs began to release a commercial version and license the system to different users. One of the users was the Department of Computer Science at the University of California, Berkeley. Berkeley added many new features to the system that later became the standard.
In 1975, Berkeley released its own version of UNIX through its subsidiary BSD. The BSD version of UNIX became the main competitor to the AT&T Bell Labs version, and other independently developed versions of UNIX also began to emerge.
In 1980, Microsoft developed a UNIX PC version called Xenix. AT&T released the first commercial version. It was called System III and was later replaced by System V, which became a good support for commercial software products.
At the same time, the BSD version of UNIX continued to develop. In the late 1970s, BSD UNIX became the basis for scientific research projects of the Department of Defense's high-tech research institutions. As a result, Berkeley released a working version called BSD Release 4.2.
It includes an advanced file manager and networking features based on the TCP/IP network protocol. TCP/IP is now used by the Internet. BSDRelease4.2 is adopted by many manufacturers, such as SUN Microsystem.
The emergence of different versions of UNIX led to the need for UNIX standards, and software developers did not know which version their programs were suitable to run on. By the mid-1980s, two competing standards had emerged, an AT&T-based version of UNIX and a BSD version. In bookstores today you can find different books for the two versions of UNIX, some for System V and others focused on BSD UNIX.
AT&T established a new organization called the UNIX System Laboratory. Its role is to integrate different versions of UNIX and focus on developing a standard system.
In 1991, the UNIX Comprehensive Laboratory integrated all the features of System V Release3, SUN OS and Xenix and released System V Release 4. In order to compete with System V Release 4, some other companies, such as IBM and HP's Open Software Foundation (OSF), produced their own standard versions of UNIX, and two standard commercial versions emerged: OSF version and System Release 4.
In 1993, AT&T sold its UNIX to Novell. The UNIX Systems Laboratory became part of Novell's UNIX Systems Group. Novell released its own version of UNIX, UNIXWare, based on System V Release 4, which can be linked to Novell's Netware system. SUN has integrated System V Release 4 into its SUN OS and released Solaris. Two competing graphical user interfaces used by UNIX (one called Motif and the other Openlook) have been merged into a new work platform standard called the Common Platform Environment (CDE).

1.2 History of UNIX development

- 1991年10月5日，赫尔辛基大学的一名研究生Linus Benedict Torvalds在一个Usenet新闻组（comp.os.minix）中宣布他编制出了一种类似UNIX的小操作系统，叫Linux。新的操作系统是受到另一个UNIX的小操作系统——Minix的启发，该系统是由一名叫Andrew S Tanenbaum的教师开发的。读者也许猜想所发布的这个系统应该是Linux的0.01版本，实际上不是这样。真正的Linux 0.01版本并没有被发布，原因是0.01版本不实用。Linus仅仅在第一个Linux的FTP站点（ftp://nic.funet.fi）上提供过这个版本的的源代码。

The version of Linux released by Torvalds on October 5, called version 0.02, can run the GNU Bourne Again Shell (bash) and the GNU C compiler (gcc) as well as a handful of other languages. Torvalds had absolutely no idea that the operating system he envisioned for advanced hobbyists and hackers would become known as Linux.
The version of Linux when it was released was 0.02, and later there was version 0.03, and then it jumped to version 0.10. Because more and more programmers around the world have started developing Linux, it has reached version 0.95. This means that the time for releasing version 1.0 is not far away. The official version 1.0 was released in 1994.

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2. Open source

Linux is a free and open source UNIX-like operating system. The kernel of the operating system was first released by Linus Torvalds in 1991. Later, after adding user space applications, it became the Linux operating system system. Strictly speaking, Linux is just the operating system kernel itself, but "Linux kernel" is usually used to express this meaning. Linux is often used to refer to a complete operating system based on the Linux kernel, which includes GUI components and many other practical tools.
The GNU General Public License (GNU GPL or GPL for short) is a widely used free software license agreement. Originally written by Richard Stallman for the GNU project, the GPL gives computer programs free software According to the definition, any products derived from GPL software must be released under a GPL license and the source code must be disclosed.
Linux is the most famous example of free software and open source software development. As long as the GNU General Public License is followed, any individual or institution can freely use all the underlying source code of Linux, and can also modify and redistribute it freely. With the rapid development of the Linux operating system, various open source software and practical tools integrated on Linux have also been applied and popularized. Therefore, Linux has become synonymous with open source software.

3. Official website

Linux official website

4. Current status of enterprise applications

The development of Linux in the server field

As open source software becomes more and more influential around the world, Linux server operating systems occupy more and more market shares in the entire server operating system market, and have formed a large-scale market application situation. And maintain a rapid growth rate. Especially in key national fields such as government, finance, agriculture, transportation, and telecommunications. In addition, considering the rapid growth of Linux and the support of relevant national policies, Linux server products will definitely be able to impact the larger server market.
> 据权威部门统计，目前Linux在服务器领域已经占据75%的市场份额，同时，Linux在服务器市场的迅速崛起，已经引起全球IT产业的高度关注，并以强劲的势头成为服务器操作系统领域中的中坚力量.

The development of Linux in the desktop field

In recent years, especially in the domestic market, the development trend of Linux desktop operating systems has been very rapid. The Linux desktop operating system launched by domestic system software manufacturers such as Kirin Linux, Hongqi Linux, and Deepin Linux has been widely used in government, enterprises, OEM and other fields. In addition, SUSE and Ubuntu have also launched Linux-based desktop systems, especially Ubuntu Linux, which has accumulated a large number of community users. However, from the perspective of the overall function and performance of the system, there is still a certain gap between the Linux desktop system and the Windows series, mainly in terms of system ease of use, system management, software and hardware compatibility, and software richness.

The development of Linux in the mobile embedded field

Linux's low cost, powerful customization capabilities, and good portability have made Linux widely used in embedded systems. Currently, Linux is widely used in mobile phones, tablets, routers, televisions, and electronic game consoles. The Android operating system widely used on mobile devices is built on the Linux kernel. At present, Android has become the most popular smartphone operating system in the world. According to the latest statistics from authoritative departments in 2015, the global market share of Android operating system has reached 84.6%.

In addition, Cisco also uses customized Linux in network firewalls and routers, and Alibaba Cloud has also developed a Linux-based operating system "YunOS", which can be used for smartphones, tablets, and Internet TVs; common digital video recorders, stage lighting Control systems are gradually being implemented using customized versions of Linux, and all this is due to the power of Linux and open source.

The development of Linux in the field of cloud computing/big data

The rapid development of the Internet industry has promoted the formation and rapid development of cloud computing and big data industries. Cloud computing and big data are platforms based on open source software, and Linux occupies the core advantage; according to research by the Linux Foundation, 86% of companies have The Linux operating system is used to build cloud computing and big data platforms. Currently, Linux has begun to replace Unix as the most popular operating system for cloud computing and big data platforms.

5. Release version

Debian
Debian is extremely stable, which makes it ideal for use on servers. The debian operating system is undoubtedly not suitable for novice users, but for system administrators and advanced users.
Ubuntu
Ubuntu is a derivative of Debian and the most popular free operating system today. Ubuntu focuses on its applications in this market and is common on servers, cloud computing, and even some mobile devices running Ubuntu Linux. Ubuntu is an operating system that novice users will definitely fall in love with.
Red Hat Enterprise Linux

This is the first Linux distribution targeted at the commercial market. It is available in server versions and supports numerous processor architectures, including x86 and
x86_64. Red Hat trains and certifies system administrators through the course Red Hat Certified System Administrator/Red Hat Certified Engineer (RHCSA/RHCE).

CentOS

is an enterprise Linux distribution built from the ground up using free source code from Red Hat Enterprise Linux. This refactored
version completely removes the registered trademark and a very subtle change in the Binary package. For some people who don't want to pay a fortune and want to get a taste of Red Hat Enterprise Linux, CentOS is worth a try. Additionally, CentOS appears to look and behave exactly like the parent distribution, Red Hat Enterprise Linux. CentOS uses YUM to manage software packages.

- Fedora

Small Fedora is for those who want to try the latest technology and can't wait for the stable version of the program to be released. In fact, Fedora is a test platform of Red Hat; products are developed and tested on this platform before becoming an enterprise-level distribution. Fedora is a very good distribution, with a huge user forum and a large number of software packages in the software library.

- Kali Linux

Kali Linux is a derivative of Debian. Kali is designed for penetration testing. Kali's predecessor was Backtrack. All Binary packages for Debian can be installed on Kali Linux, and this is where the charm or power of Kali comes from. In addition, the user forum that supports Debian adds a lot to Kali. Kali comes with many penetration testing tools, whether it is Wifi, database or any other tools, all designed to be used immediately. Kali uses APT to manage packages.
There is no doubt that Kali Linux is a penetration testing tool or the favored operating system of civilized hackers (I don’t want to talk about malicious hackers).