Linux you don't know

Mr. Inamori’s words in the Living Act have always inspired me and are now being forwarded to you who are reading this article:

"Working so hard, just want to find happiness in interest and games, at best, you can only get a moment of pleasure, you can't taste the surprise and happiness from the bottom of your heart, but the joy from work is not like candy - put it in your mouth It is full of sweetness, but needs to be exuded from hard work and hardships. Therefore, when we concentrate on our work and tirelessly overcome the sense of accomplishment after hardship, there is no such thing as an analogy in the world." "Not to mention that work in human life occupies a large proportion. If you can't get a sense of fullness from work and work, then even if we find happiness from other places, we will still feel empty and shortcomings."

Learning is a chore

I don't want to avoid this problem - learning is a painful thing. If learning Linux is really simple, it must be a lie of a liar. At least this will not bring you a high salary. In the few minutes after each wake up, the brain will be in a state of struggle - whether it is a chat, or a US drama, or a League of Legends, or a look at the damn Liu Wei What a terrible Linux textbook? At this time, please don't forget your original dream. After ten years, you will be grateful to yourself who are desperately trying to learn. As an author, my mission is to make this book worthy of the time, effort, and money you spend on it, so that every time you finish a chapter, it's an improvement.

Remarks: This article is taken from "Linux should be like this". I am the author of this book.

Open source sharing spirit

To put it simply, open source software is characterized by packaging software programs together with source code files for users, allowing users to modify them on an as-needed basis, or to compile them as derivatives. Released. Users have the freedom to use freedom, modify freedom, reissue freedom, and create derivatives. This is also in line with the pursuit of freedom by hackers and geeks, so the roots of the open source community at home and abroad are very large and popular.

To be frank, every technician or programmer who is committed to the Linux industry will be proud of hearing open source projects. This is a unique feeling from the bones. Open source enterprises are not solely for the benefit, but support each other and strive to serve more users. The most important features of open source software are the following.

Low risk: Using closed source software will undoubtedly deliver the fate to others. Once the closed source code is not maintained, you will be in a dilemma; and compared to commercial software companies, the open source community rarely has a problem of bankruptcy.

High quality: Compared with closed source software products, open source projects are usually developed and maintained by the open source community. There are many users involved in writing, maintaining, and testing. The general bugs have not been fixed after the outbreak.

Low cost: Open source workers are working behind the scenes silently and freely to contribute to the good world, so using open source community-driven software projects can save a lot of manpower, material resources and financial resources.

More transparent: no idiot will put Trojans, backdoors, etc. in open source code, which is undoubtedly exposing his crimes to the sun.

However, if open source software sacrifices the interests of programmers in pursuit of "freedom", this will affect the creative passion of programmers. Therefore, there are more than 60 open source license agreements recognized by the Open Source Initiative in the world. To ensure the rights of open source workers. For those who are ignorant of plagiarism, tampering, cracking or pirating other people's works, they will eventually receive a subpoena from the court one day. For developers who are ready to write an open source software, it is also very recommended to first understand the current hottest open source license agreement, choose a suitable open source license agreement to maximize the protection of their software rights.

GNU GPL (GNU General Public License): As long as the software contains products or codes that comply with the GPL, the software must also comply with the GPL license and be open source and free, so this agreement is not suitable for commercial software. . The number of open source software that follows the agreement is extremely large, and most open source software, including Linux systems, is based on this protocol. The four biggest features of the GPL open source license agreement are shown below.

Freedom of Copy: Allows the software to be copied to anyone's computer without limiting the amount of copying.

Freedom of communication: Allows software to spread in various forms.

Fee-spreading: The software is allowed to be sold on a variety of media, but the buyer must be informed in advance that the software is freely available; therefore, in general, open-source software is profitable by providing paid services to users.

Freedom of modification: Allows developers to add or remove features of the software, but the software must still be licensed under the GPL license.

BSD (Berkeley Software Distribution) License Agreement: Users can use, modify, and redistribute software that complies with the license, and can publish and sell the software as commercial software, provided the following three conditions are met.

If the re-released software contains source code, the source code must continue to follow the BSD license agreement.

If there is only a binary program in the re-released software, you need to declare the original code in the relevant document or copyright file to follow the BSD protocol.

Marketing, including the name of the original software, the author's name, or the organization's name is not allowed.

Apache License Version License Agreement: Allows users to have the freedom to modify code and redistribute while providing developers with copyright and patent licenses. The license agreement applies to commercial software. Now the popular Hadoop, Apache HTTP Server, MongoDB and other projects are developed based on the license agreement. Program developers must strictly observe the following four conditions when developing software that complies with the protocol.

The software and its derivatives must continue to use the Apache license agreement.

If the program source code is modified, it needs to be declared in the documentation.

If the software is written based on other people's source code, you need to retain the original code's agreement, trademark, patent statement and other original author's content information.

If there is a declaration file in the re-released software, the Apache License Agreement and other license agreements need to be marked in this file.

MPL (Mozilla Public License) license agreement: Compared to the GPL license agreement, MPL pays more attention to the balance between the source code requirements and benefits of developers.

MIT (Massachusetts Institute of Technology) License Agreement: One of the least restrictive open source license agreements, as long as the developer of the program retains the original author's license information in the modified source code, and is therefore generally used by commercial software.

Why study Linux?

As early as the 1970s, UNIX systems were open source and free. But in 1979, AT&T announced a commercialization plan for UNIX systems, and the open source software industry turned into a copyright-based software industry. The source code was treated as a trade secret and became a patented product. People could no longer enjoy it freely. Technological Achievements.

So in 1984, Richard Stallman launched the GNU source code open plan and developed the famous GPL license agreement for such a closed software creation environment. In 1987, the GNU project received a major breakthrough - the gcc compiler release, which allows programmers to write their own open source software based on the compiler. Then, in October 1991, Linus Torvalds, a student at the University of Helsinki in Finland, wrote an operating system called Linux. The system was quickly supported by the GNU Project and a large number of hacking programmers due to its high code quality and open source features based on the GNU GPL license. Then the Linux system entered a stage of development in full swing.

In January 1994, Bob Young integrated a large number of source code and program software based on the Linux system kernel, released Red Hat system and began to sell technical services, which further promoted the popularity of Linux systems. After 1998, with the GNU source code open plan and the Linux system continue to be hot, many IT giants led by IBM and Intel began to promote the development of open source software. By the end of 2017, the Linux kernel has evolved to version 4.13, and there are hundreds of Linux system versions, but they still use the Linux system kernel developed and maintained by Linus Torvalds. RedHat has also become a leader in the open source industry and Linux systems.

During the lecture, I often asked my classmates a question: "Why do you learn Linux?" Many students just said that "because the Linux system is open source, it is necessary to learn" in order to make me happy. In fact, this idea is completely wrong! Open source operating systems are less than 100, and open source software is at least 100,000. Why not learn one by one? So the open source feature mentioned above is only a part of the advantages, not enough to be your reason to study hard.

For the user, the open source spirit only has the icing on the cake, so the correct learning motivation should be derived from: Linux system is an excellent software product, with a UNIX-like program interface, and inherits the stability of UNIX, can be compared Goodly meet the needs of the work.

Most readers should start to understand computers and networks from Microsoft's Windows system, so there must be such an idea. "Windows systems are very useful, and they are enough to meet the daily work needs." Objectively speaking, the Windows system is really excellent, but it is not satisfactory in terms of security, high availability and high performance. You should have seen the picture below.

Linux you don't know

Presumably, readers can now guess why Linux systems are used in web servers that need long-term stable operation, in cluster systems that handle big data, and in environments that need to work together. The following figure also shows the specific advantages of the Linux system compared to the Windows system.

Common Linux system version

Before introducing the common Linux system version, you first need to distinguish between the Linux system kernel and the Linux distribution system.

The Linux kernel refers to a system core program maintained by Linus Torvalds that provides hardware abstraction layer, hard disk and file system control, and multitasking.

The Linux distribution system is what we often call the Linux operating system, which is a collection of Linux kernels and various commonly used software.

There are hundreds of Linux system versions in the world. Each system version has its own characteristics and target population. The following will select the most popular ones from the user's point of view.

Note:

The entire article will replace the term "Linux distribution system" with "Linux systems."

Red Hat Enterprise Linux (RHEL): Red Hat is the world's largest open source technology vendor, and RHEL is the most widely used Linux system in the world. The RHEL system is extremely stable and stable, and has comprehensive technical support on a global scale. The RHEL system is also the system used in this article, Red Hat certification, and many production environments.

Community Enterprise Operating System (CentOS): A widespread use of the Linux system by recompiling and publishing the RHEL system to users for free use. CentOS is currently "incorporated" by Red Hat.

Fedora: A desktop version of the system suite released by Red Hat (currently not limited to the desktop version). Users can experience the latest technology or tools for free. These technologies or tools will be added to the RHEL system when they are mature, so Fedora is also called the "test field" of the RHEL system. If the operation and maintenance personnel want to keep their technology leadership at all times, they should pay more attention to the development and new features of such Linux systems and constantly change their learning direction.

openSUSE: A well-known Linux system from Germany, with a good reputation and market share worldwide.

Gentoo: Extremely customizable and complex to operate, so it is suitable for experienced personnel. Readers can try the system after they have finished the book.

Debian: It is stable and secure. It provides free basic support, supports various hardware architectures well, and provides nearly 100,000 different open source softwares. It has high recognition and usage in foreign countries.

Ubuntu: is a Debian-derived operating system that is extremely compatible with new hardware. Ubuntu and Fedora are both excellent Linux desktop systems, and Ubuntu can also be used in the server space.