Shulou(Shulou.com)06/01 Report--

This article introduces the relevant knowledge of "how to understand Linux". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Content introduction

1. Syllabus

Part one lesson 1: what is Linux?

3, the first part of the second lesson preview: download Linux, free Oh!

make clear the purpose and main theme from the very beginning

We always hear people say that Linux is complicated and is for programmers who seek to force the grid. We ordinary people are happy to use Windows.

But this is not the case, Linux is not so "difficult to rise to the sky".

Many people who study programming have seen "Brother Bird's Linux Private Cuisine". It was written by Brother Bird in Taiwan.

The editor also began to write a series of tutorials, hoping to be helpful to himself and others. But I'll be very serious. I won't do anything wrong.

In this tutorial, the editor will prove to you that Linux is not complicated.

If you don't know what Linux is, it doesn't matter at all, this tutorial is for beginners.

The object of this course is:

Those who use Windows or Mac but want to know about Linux

People who are beginners of Linux and want to have better control of Linux

Network administrator, who wants to manage the server under Linux

Other people who are interested in Linux

What is Linux?

Nowadays, it is difficult to say that you have not heard of Linux.

When the editor was in junior high school (his age was accidentally exposed at the beginning of the 20th century), he first saw Linux on a computer in the school's computer room. But I have never had a chance to use it, because there is only one computer with Linux, and everyone still uses Windows for class. At that time, I only remember that cute penguin from Linux.

Today, Linux is almost ubiquitous: the servers of most websites are Linux systems; the underlying Android system uses a modified Linux kernel; and Ubuntu (a Linux distribution, described below) mobile phones.

Editor, you've been talking for a long time, so what on earth is Linux?

Don't worry, we will introduce you to Linux step by step in today's lesson. We will begin to install the development environment in the next lesson.

What is an operating system?

When it comes to Windows, probably everyone knows, everyone knows. It is the main operating system of Microsoft (Bill Gates' Microsoft empire). For example, there is Win CE in embedded system, so we won't talk about it.

In the past, Windows really dominated the desktop PC (PC means "personal computer", meaning Personal Computer).

Now Apple's Mac computer is also beginning to rise, and the share of the Linux has also increased, but the two still fall far behind the Windows. All versions of Windows (Win XP,Windows 98, Windows Vista,Win 7 Magi win 8, etc., etc., followed by Win 10 Magi Windows skipped Win 9, directly from Win 8 to Win 10) together account for more than 90% of the desktop world.

February 2015 Desktop operating system share:

Although Windows continues to dominate desktop PC, it has a small share of mobile devices (phones, tablets, watches, etc.). It is generally a place where iOS and Android compete for supremacy.

Most desktop computers are pre-installed with Windows, or Windows as the distribution system.

So what does that mean?

You might say, "it's not easy, that is to say, you see the Windows logo when you turn on the computer."

Although this is not complete, it is undeniably a good start.

When you turn on a computer with a Windows preinstalled system, the first thing you see may be the following image:

Of course, the image above will change with different versions of Windows. But the main point we want to make is that when the computer starts, Windows also starts.

Boot: computer on

Most people have the impression that when the computer starts, Windows starts first. But if we are more careful, we can observe that in the first few seconds of the computer boot, a series of images are displayed on the screen, commonly known as the "startup interface". The icon for Windows is displayed later.

For the "startup interface", we do not take screenshots, because different computers, this part of the information is not the same.

Why?

Because it has something to do with the computer's hardware. In fact, it is the computer's motherboard (mother board) that displays the "startup interface".

The motherboard is the most important part of the computer, because it is the motherboard that makes our processor run, the hard disk can be read, and the CD can be played. Motherboard (English is Motherboard, Mainboard, referred to as Mobo), also known as motherboard, system board, logic board, motherboard, backplane, etc., is the center or main circuit board of complex electronic systems such as electronic computers. As follows:

So, when the computer starts, the following two things happen in order:

"launch interface"

Startup of Windows

Only when Windows starts smoothly can we use a variety of applications: browsers, drawing software, games, music players, and so on.

So why do you have to start Windows first? Why can't the programs we usually use, such as drawing software, be used after starting the interface?

Because your computer needs a "butler"-like software, just like the chief conductor of an orchestra, to direct the performance of various musicians. This "butler" software needs to manage your computer's memory and allocate it reasonably to each software. It acts as a "bridge" between computer hardware (memory, graphics card, optical drive, etc.) and various software.

This task sounds noble and sacred, doesn't it?

This "butler" software is the operating system, or OS, which is the initials of Operating System (operating means "operation" and system means "system"). After the course, we often use the abbreviation OS to refer to the operating system, please remember.

And our Windows is an operating system.

So if we sum up, the computer will perform the tasks in the following order:

Launch interface

Boot of an operating system (such as Windows)

The startup of other programs (or software)

Maybe it's easier to understand with an illustration:

Linux is an operating system

Editor, don't forget that this tutorial is about Linux. Why are you talking about so much Windows?

Don't worry, I haven't forgotten our original intention. After the above hu (che), you should have a general understanding of the operating system, so I will announce a "shocking" news: Linux is an operating system. Similarly, there is Mac OS, an operating system developed by Apple.

Compared to Windows,Linux, it is known for its reliability and security, and it is updated frequently, unlike Windows, which does not have to wait a long time for an update. We will slowly discover these advantages of Linux in this journey of exploration.

You may want to ask again: "can we have two OS on the same computer? I don't want to uninstall Windows in order to install Linux. I have to play games, my Dota."

Many people may think that a choice needs to be made: install Linux or Windows. But this is not the case: a computer can have two (or more) operating systems.

In this case (multiple operating systems), when the computer starts up, when the startup interface ends, a program called bootloader will be displayed, allowing you to choose which operating system to start.

What is bootloader?

Excerpt from Baidu Encyclopedia's explanation:

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Bootloader is a piece of Mini Program that runs before the operating system kernel runs. Through this Mini Program, we can initialize the hardware devices and establish a memory space mapping, thus bringing the software and hardware environment of the system to an appropriate state, so as to prepare the correct environment for the final call of the operating system kernel. In general, Bootloader is heavily dependent on hardware, especially in the embedded field.

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The most commonly used bootloader that enables us to choose between Linux and Windows is called GRUB. If you don't make a choice, the GRUB bootloader will start the default operating system in a few seconds. Of course, you also set the default operating system.

A thousand words are not as good as a picture. Let's take a look at the startup process of a computer under a dual operating system:

In the figure above, we can see that when we are in the Linux system, the programs we use are customized for Linux, not Windows programs, and vice versa. In fact, Windows programs don't work under Linux, and vice versa.

Of course, there are some technologies that can make Windows programs run under Linux, the more famous of which is Wine. However, even though some Windows programs can be run under Linux after using Wine, it is better to use a program tailored for Linux because it is faster.

You may want to say again: "but I am used to all kinds of programs under Windows, and I can't use the programs under Linux."

In fact, it's not that hard. You'll probably be familiar with Linux programs in a few days, and if you're active and interested, maybe one night.

Programs on Linux have many advantages:

Free: basically all programs on Linux are free

Updates are frequent and free

There are many Linux versions of programs that are better than Windows versions, and some programs that don't have Windows versions (of course, some programs are available on Windows and Linux, such as many big games). Programs under Linux tend to make you more efficient because they can use computer resources more efficiently

But why are almost all programs under Linux free? So the people who developed these programs are not going to lose money?

Let's talk about the reasons.

Heaven and earth domineering, men fall to the ground: the birth of Linux

I remember being tricked by a good friend into reading a spoof cartoon about Brother Chun (Li Yuchun), although I only read the beginning, it seems to be called the Biography of Brother Chun. However, the title of the first volume is still fresh in my memory: "Heaven and Earth domineering, Men landing." So I would also like to borrow it here to show the domineering side leakage of Linux.

First of all, Linux's domineering performance in the "pure man". I'm sorry for the mistake, but it's about the price:

The genuine Windows system costs a few hundred dollars (different versions vary in price, with the Windows website being the most expensive)

Linux is free!

Take a look at the price of Windows version 8.1 found by the editor on Windows's website: $120. at the current exchange rate of US dollars to RMB: 1: 6.2, that is 745 yuan. It's expensive, not to mention the expensive programs in Windows, which costs hundreds of dollars for an Office:

Seeing this comparison, many people will think to themselves, "Linux is free, it must be because Linux is shoddy."

Then you are dead wrong.

Linux is free, and almost all programs running on Linux are free for a reason. And to understand why, we have to go back to 1984 and start talking about it from then on.

Information Technology in 1984

Back in 1984, information technology was far less developed than it is today. At that time, Microsoft had just released its first operating system: MS-DOS, also known as the DOS operating system.

Of course, DOS was not developed by Microsoft. Back in 1980, Tim, a 24-year-old programmer at a computer products company in Seattle. Tim Paterson spent four months writing the 86-DOS operating system. In July 1981, Microsoft bought all the rights to DOS from Seattle computer products and renamed it MS-DOS. Gates bought the entire copyright of DOS for only $50, 000.

Although Microsoft later paid Seattle computer products another $1 million to settle the lawsuit in 1986, that $1.05 million was a drop in the bucket compared to the money Microsoft made from DOS.

In the end, Bill Gates is a pirate-like figure, from the rise of DOS to the domination of Windows NT, Microsoft can be said to be doing dishonorable "activities", deceiving a lot of companies. Interested readers can take a look at the book "the Top of the Wave" and the movie "Pirates of Silicon Valley", all of which talk about the history of Microsoft.

It's too far. We'll pull it back in time.

Although the DOS operating system was very popular at that time, the system itself had many limitations and was not so good.

If you have used the original Windows system, you must have heard of the DOS system. It looks like this:

So, in those days, was DOS the only operating system?

No, there are many operating systems, but most of them are not famous.

Of course, there is a famous operating system, and that is "Unix". Unix is much more powerful than DOS, but it is more complex to use, so only professional information engineers used Unix at that time.

Unix is also much older than DOS. Unix was born in 1969 (or 1970).

From the point of view of the user interface, Unix is very much like DOS: white words on a black background. Of course, computers at that time could only do so.

GNU project

The picture above is the logo of the GNU project, because GNU means "wildebeest" in English.

In fact, GNU is a recursive abbreviation for "GNU is Not Unix" (this English sentence means "GNU is not Unix"). There is often such a name in the computer world, and foreigners are cute.

In the same year that Microsoft released DOS, in 1984, Richard Stallman (Richard. Stallman founded the GNU project.

Who is Richard Stallman? Maybe a lot of people haven't heard of that name.

But this senior is very good. He is:

Free Software Foundation (Free Software Fundation, referred to as FSF). Of course, the "Free" here means "free", not "free".

The founder of the GNU project. The GNU General Public license (GNU GPL), which he wrote, is the most widely used free software license in the world, opening up a new path for the concept of copyleft. Because GNU is open source code, in order to prevent unscrupulous manufacturers from using free software to make it proprietary. Stallman original, created Copyleft authorization method, so that all GNU programs follow a "Copyleft" principle, that is, can be copied, can be modified, can be sold, but there is one: all improvements and modifications to the source code must be disclosed to every user, and all users can get the changed source code. Copyleft ensures the continuity of free software transmission.

Famous hacker (note: hacker is actually a commendatory term, refers to those very skilled masters), was born in Manhattan, New York in 1953, entered Harvard University in 1971, and was employed by MIT artificial Intelligence Lab (AI Laboratory) in the same year.

Representative works: Emacs (mentioned in the last article we introduced Emacs), GCC (abbreviation of GNU Compiler Collection, meaning "GNU compiler collection", wide range of compilers, and even many variants in embedded field), GDB (abbreviation of GNU project DeBugger, meaning "GNU project debugger", widely used debugger)

He has received many honorary medals, including the Grace Hopper (Grace) awarded by the American computer Association in 1991. Hope) Award (remember our first generation of female programmers: Grace. Hope? In the first part of the "Journey to explore the C language", the first lesson "what is programming? It has been introduced that the legendary female programmer invented the word bug)

The primary purpose of the GNU project at that time was to create a Unix-like operating system. Of course, the operating system not only had a kernel, but also included some underlying basic applications, such as compilers, linkers, assemblers, text editors, and many API (Application Programming Interface, application programming interfaces are predefined functions. The purpose is to provide applications and developers with the ability to access a set of routines based on some software or hardware without having to access the source code or understand the details of the internal working mechanism.

Then you have to ask: "since you already have such a good operating system as Unix, why do you want to copy a Unix?"

Because Unix is not free, it is commercial software (strictly speaking, it is free at first, and it can be used for school teaching for free, but later it is no longer available), the price is a little more expensive than the genuine Windows, and it is simply unbearable.

For this reason, Richard Stallman created the open source GNU project to benefit himself and others.

Additional knowledge: Apple's Mac OS is also based on Unix. However, today's DOS has little to do with the Windows system (the original Windows and the remains of DOS).

GNU is a free operating system

GNU is not only a free operating system, but it is also free (later called "open source", but it is slightly different from the original intention of Richard Stallman).

We say that a software is free, so what's the difference between it and free software?

Free software means that the source code must be made public. For example, Linux is a free operating system, and we can search all versions of its source code on the Internet. On the other hand, Windows and Mac OS are not free, but private, and you can't find their source code, otherwise Microsoft and Apple will go crazy. The Windows and Mac OS operating systems are a bit like Coca-Cola. We can enjoy them, but no one knows the recipe for Coca-Cola. For software that is not open source, we cannot modify the source code (the source code is like a recipe, right?), nor do we know the internal mechanism.

Free software is free most of the time, but it can also be copied, modified and sold.

Proponents of free software believe that if the source code is open, the software can be assisted by many parties and updated faster.

The slogan of the freedom movement is: "Unity is strength" (our Party's insights are so far-sighted).

Linus Torvalds dominating side leakage

In 1991, Linus Torvalds (Linus Torvalds), who is known to everyone in the field of programming today, is the author of the Linux operating system (strictly speaking, the Linux kernel). At that time, a student at the University of Helsinki in Finland decided to write a Unix-like operating system (kernel) in his spare time, and finally developed version 1.0 for him.

The name Linux can be said to be a combination of Linus and Unix, or a recursive abbreviation for "Linux Is Not Unix". The following is a picture of Linus:

Just as GNU has its mascot, a wildebeest. Linux also has its mascot: a cute male penguin named Tux (man, 24K pure drop). Tux means "tuxedo" in English (the official name is "tuxedo"). Does the black back of a penguin look like a tuxedo? And looks a bit like Uncle Linus.

So in the end, the mascot of Linux is decided to be a penguin, which is still very cute. It turns out that Linus's decision is not wrong, and this cute penguin has melted the hearts of many programmers. At least the editor likes him a lot.

So what is the connection between Linux and the GNU project?

That's a good question.

It can be said that the two projects are complementary: when the first version of Linux was released by Linus in 1991, the GNU project had already created a lot of peripheral software of the operating system, such as programs that copy files (cp command), programs that delete files (rm command) text editor (Emacs), compiler (GCC), debugger (GDB), etc., but do not have their own kernel (Kernel). The emergence of Linux (Linus actually wrote a Unix-like kernel, and then successfully ported some GNU programs). Later, the work of perfecting Linux was handed over to hackers from Linus and the vast open source community. They have been working conscientiously to achieve the glory of today's Linux. So it's not Linus alone, he's a Finnish hairy kid standing on the shoulders of the giants of the open source community.

So, GNU project (various open source programs) + Linux (operating system kernel) = GNU/Linux this complete operating system.

The wildebeest living on the African prairie and the penguins symbolizing the ice and snow of Finland complement each other and blend with ice and fire, making a legend. ("just because I took one more look at you in the crowd.")

Let's get this straight:

The core of the operating system is called the "kernel", but the kernel is not the same as the operating system. The kernel provides system services, such as file management, virtual memory, device Imax O, and so on. In addition to the kernel, there is usually some middleware API between the application software and the kernel, which can be called by the application, as well as some basic programs, such as text editor, compiler, shell (shell, such as commonly used Bash), and so on.

The Linux kernel does not work alone, and there must be many applications of the GNU project to contribute to it. You can imagine that the kernel is a bit like the foundation of a house (reinforced concrete), and the surrounding basic applications are equivalent to the various facilities of the house, so that a house can be used by different people or animals (third-party applications, such as QQ, Thunderbolt, etc.). "

Therefore, the official name of Linux should be "GNU/Linux", but the name is a little complicated and its pronunciation is not easy, so we usually use the abbreviation: Linux.

Convention: in the following lessons, if it refers to the Linux kernel, then the editor will use the "Linux kernel"; if it refers to the GNU/Linux operating system as a whole, then the editor will use "Linux".

Use a diagram to summarize the relationships of each system:

Now we should have a certain understanding of the origin of the world's three most commonly used desktop operating systems (Windows,Linux and Mac OS).

Both Mac OS and Linux are based on Unix,Unix, which can be said to be their ancestors. The ancestor of Windows is DOS, although most of the versions of Windows we use today are based on the revolutionary Windows NT kernel (you can read the wonderful book "wait and see-Microsoft's creation of NT and the desperate run of the Future").

We say that Mac OS and Linux are based on Unix, just that they reproduce the mode of operation of Unix. The source code is basically different, especially the Linux kernel, which is written entirely from scratch by Linus, although much of the code is similar to Unix. And many programs of the GNU project are similar to those of Unix, even with the same names, such as cp command, rm command, mv command and so on.

Having said so much, I hope readers will not dislike Xiaobian for being verbose (of course it is a bit wordy. Ahem), but it is so painstaking (is he a pure man? 24K) just to make people have a general framework for these basic concepts, so that the follow-up courses are easier to understand.

Different Linux distributions

Today, Linux is a very complex and rich operating system, and most of its source code is from the GNU project.

Because it is open source free, Linux is not as rigid as Windows, you can customize your own Linux system, as long as you are good enough, you can cut and modify the source code of Linux.

But also because of this, some beginners have a bit of a big head, online search Linux, there are so many versions, which kernel version to use? Then which applications are installed? And the installation method is different.

This is what makes it difficult for ordinary users. By contrast, the selection and installation of Windows is much easier.

In order to simplify the process of user installation, and provide some basic software, such as browsers, communication software, terminals, drawing software, text editors, etc., a lot of Linux distributions have been produced, and these Linux operating systems can be said to be a complete set of operating environment: kernel, API, and various pre-installed applications.

This concept of "release" does not exist in Windows, although we have Win 7 home version and Win 7 flagship version, but it is not the same.

The main differences between different Linux distributions are as follows:

Installation methods are different: some are complex, some are simple

The way to install applications is different: if well designed, it is very convenient for a Linux distribution to install applications, much easier and faster than under Windows. We'll see in the rest of the course

Pre-installed applications are different: just as Windows has pre-installed software, such as IE browser, Media player (Windows Media Player), etc., different Linux distributions also have different pre-installed software.

You can think of different distributions of Linux as modern girls with the same core (the kernel of Linux is almost the same on Linux distributions) and different decorations.

Different Linux distributions

There are many Linux distributions around the world, all of which are free (there are also individual versions charged, such as the enterprise version of Red Hat), which is difficult to choose. Let's take a brief look at the most common Linux distributions, and then the editor will make the best choice for you.

RedHat: the most familiar and well-heard distribution for Linux users in China and even around the world must be RedHat. Stable performance, old Linux distribution. The charge is RedHat Enterprise Linux (the enterprise version of RHEL,RedHat), while the orthodox version of RedHat has long since ceased technical support, and the last version is RedHat 9.0.

Mandriva: first created by Garl Duval and released in July 1998. In the past, when Linux was first popularized in China, Mandrake was very popular. When it comes to the history of Mandrake, in fact, the earliest developers of Mandrake were based on Redhat. Redhat defaults to the GNOME desktop system, while Mandrake changes it to KDE. At that time, Linux was generally difficult to install and was not suitable for beginners who came into contact with Linux for the first time, so Mandrake also simplified the installation system.

SUSE: Germany's most famous Linux distribution, which also enjoys a high reputation all over the world. The software package management system YaST developed by SUSE has also been well received. SUSE was acquired by Novell at the end of 2003.

Debian: first founded by IanMurdock in 1993. It can be regarded as the most GNU-compliant Linux system so far. The Debian system is divided into three versions (branch): stable,testing and unstable.

Gentoo: originally created by Daniel Robbins, one of the former developers of Stampede Linux and FreeBSD. Gentoo is famous for its high degree of customization: because it is a source code based (source-based) distribution. Although you can choose a precompiled package during installation, most users who use Gentoo choose to compile it manually.

Slackware: founded by Patrick Volkerding in 1992. It's supposed to be the oldest Linux distribution. Slackware used to be very popular, but as Linux became more and more popular and the technical aspects of users became wider and wider (more newcomers), Slackware was gradually forgotten by newcomers.

MEPIS: established by Warren Woodford in 2003. Although MEPIS has just been established, it has spread rapidly among Linux users. Simply put, MEPIS is a product of a collection of DebianSid and Knoppix. Users can either use it as a LiveCD or install it using a regular graphical interface.

Xandros: built on the Corel Linux that has become history. At the beginning, Corel Linux's company was forced to stop the development of Corel Linux due to financial difficulties, while Xandros timely bought the Corel Linux department and launched a new Xandros Desktop in October 2002. The selling point of Xandros is its extremely simple installation and use.

FreeBSD: first of all, I want to emphasize that FreeBSD is not a Linux system! Because FreeBSD also has quite a large number of users, many of its features are similar to Linux. In fact, Linux and BSD (Berkeley Software Distribution) are both evolutionary branches of UNIX. Moreover, a considerable number of features and functions in Linux, such as the Bind software used to configure DNS, are taken from BSD. FreeBSD is the most famous distribution in the BSD family with the largest number of users.

Debian, the Linux distribution.

We will focus on Debian, the Linux distribution, because it is the most open source release, the most GNU standard, and is maintained by the open source community. Many of the above Linux distributions are maintained by the company.

Debian is so successful that it inherits Debian, and there are a number of Linux distributions:

Knoppix: Knoppix, developed by KlausKnopper in Germany, is a Debian-based distribution. Knoppix is strictly a LiveCD Linux. The so-called LiveCD means that the entire operating system is on a CD. As long as you boot from the CD, you can have a complete Linux system! No need to install!

Skolelinux: a Linux distribution produced by the Debian Edu project as a Debian Pure Blends distribution and a formal support project for Debian to provide a fully configured school network environment and school application

Ubuntu: the Linux distribution to be used in this course

Wait

If you don't feel clear enough, the following figure should help you clear your mind:

Ubuntu, the Linux distribution.

Why did we choose Ubuntu (pronunciation: Ubantu) as the Linux distribution of this series of courses?

There are several reasons (the editor won't cheat you, don't worry):

Easy to use, suitable for the general public: now the Ubuntu mobile phone is a proof. Even for beginners of Linux, the Ubuntu system is easy to use, except for the command line. The name Ubuntu comes from the word "ubuntu" in Zulu or Hausa in southern Africa, meaning "human nature" and "I exist because of everyone." it is a traditional African value similar to the idea of "benevolence" in Chinese society.

Regular and frequent updates: a new version of Ubuntu is available every 6 months and will not become obsolete

There are many users, many support communities, and complete documentation: the most fear of using a software (operating system is also software) is that the community support is not enough, the documentation is incomplete, and there is no place to ask questions. You who use Ubuntu don't have this kind of problem at all. There are countless Ubuntu users around the world who can provide you with technical support.

Standardization: the default compilation environment for Google's Android source code is Ubuntu

Summary

The operating system is a tool for connecting your computer to your applications.

Windows,Mac OS and Linux are the most commonly used operating systems

Linux is open source, which means that the source code of Linux is open and can be seen by everyone. In contrast, the source code for Mac OS and Windows is closed, and we can't see their code.

There are many different variants of Linux, the term "Linux release"

Among the many Linux distributions, Ubuntu is the most popular. It is a member of the big family of Debian, the Linux distribution, and can be said to be a successor. Ubuntu will be the Linux distribution that we have been using since the end of this course.

This is the end of "how to understand Linux". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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