The following is information about lunix:
What's the difference between lunix system and windows system? What are their advantages and disadvantages?
Before you know Linux, you have to know what an operating system (OS) is. So, first of all, let's briefly talk about what an operating system is! Let's think about it first. When we use the computer, where does the banging sound on the screen come from? Hmm! It is developed by graphics card and screen; Then you can see this article through the internet now, which is the task completed through the internet, network card, network cable and all related electronic equipment and network equipment! What should I do if I want to watch VCD? Then you need the support of CD-ROM, CD-ROM, sound card and so on. In that case, all that can be used is hardware work! Yes, it is these computer hardware that are working. So how does the hardware work? Is that achieved through the "operating system"? 1? 7? 1? 7! This operating system is to communicate messages between you, users and hardware! In other words, without an operating system, your computer hardware is just a pile of scrap metal, and you can't do any work!
So what's in the operating system? Simply put, the operating system is mainly divided into two things, one is the "core" and the other is "a bunch of tools provided by the core". Let's briefly explain it with Windows computers that users often use. Everyone should have used the file manager in the Windows computer, right? So when you open the file manager, will it display the data on your hard disk? This shows the data inside the hard disk, which is completed by the "core" for you. However, you want the kernel to display the data in which directory of the hard disk, which is achieved through the "tool" of "file manager"! Is that understandable? Similarly, if you have ever used Windows 2000 or Windows XP, so much the better! Have you heard of the so-called "FAT32 and NTFS file formats"? In the early version of Windows, Windows 98, he could not read or find the hard disk in NTFS file format of Windows XP. Why? Because his "core" doesn't understand NTFS at all! So, even if you have an archivist, because the core doesn't know NTFS at all, the archivist is incapable of helping you realize what you want to do! Should this be clearer? That's right! Your whole hardware is managed by the kernel. If the kernel doesn't know your hardware, then you can't use hard disk devices, such as the NTFS file format hard disk mentioned above! The kernel is the "kernel", which is the lowest layer of an operating system. It is responsible for the working state of the whole hardware resources, while Linux has its own kernel and Windows has its own kernel. So, when you add new hardware to your system, if your "kernel" doesn't support it, hehe, this new hardware will definitely not work, because the kernel that controls it doesn't know him! Do you understand this? ! Have a general understanding first, and then talk about it in detail when talking about "core compilation"!
Generally speaking, the transactions managed by the kernel are:
System call interface: after some services communicate with the kernel, hardware resources will be further utilized;
Process control: the system process control center, so the smaller the core, the better;
Memory management: control the memory management of the whole system;
File system management: file system management, such as I/O and so on! It also supports different file formats and so on. If your kernel doesn't know a file system, then you won't be able to use files in that file format? 1? 7? 1? 7! For example, Windows 98 mentioned above does not know the hard disk of NTFS file format;
Device driver: As mentioned above, hardware management is certainly one of Kernel's main jobs? 1? 7? 1? 7. Device driver is the core thing to do! Fortunately, there is a so-called "loadable module" function, which can edit the driver into modules without recompiling the kernel! This will also be mentioned in the subsequent core compilation!
So! All hardware resources are managed by him! As for what we want to do, in addition to the functions provided by the kernel itself (such as the file manager mentioned above), we can do it through other applications! For example, you want to watch VCD movies, right? So besides the media player provided by Windows, you can also install your own VCD player to play VCD? 1? 7? 1? 7! This player is the application software? 1? 7? 1? 7, and this application software can help you control the core work (that is, showing movies? 1? 7? 1? 7), so we can say that the core is to control the whole hardware support, and it is also the lowest level of an operating system. However, if the whole operating system wants to be more complete, it needs to be supported by quite rich tools provided by core and core-related application software!
All right! Speaking of which, do you know what Linux is? Ha ha! Yes, in fact, Linux is an operating system, which contains the most important kernel and the tools provided by the kernel! He provides a complete framework of hardware control and resource management at the bottom of a complete operating system, following the good tradition of Unix, so it is quite stable and powerful! In addition, because this excellent architecture can run on the current personal computer (X86 system), many software developers have shifted their energy to this architecture, that is, many applications! Although Linux is only the kernel and the tools provided by the kernel, due to the integration of the kernel, the kernel tools and the software provided by these software developers, Linux has become a more complete and powerful operating system? 1? 7? 1? 7! We can think of the association between Linux system and users as the following icon:
Figure 1. Correlation between users, user interface and core tools, core and hardware.
After a brief understanding of what Linux is, let's talk about "why is Linux a very stable operating system?" How did he get here? 』
History from Unix to Linux
Why do people often say that Linux is a very stable operating system? This is because Linux has an old-timer, the Unix family? 1? 7? 1? 7! With the support of this predecessor, Linux will soon become a stable and excellent operating system! So, let's talk about the history from Unix to Linux!
As early as twenty years before Linux appeared (about 1970), there was a fairly stable and mature operating system! That's Linux's big brother "UNIX"! How can you say that? ! What's the relationship between these two guys? Why don't you tell him here? 1? 7? 1? 7! As we all know, the kernel of Linux was developed by Linus Torvalds at 199 1 and put on the Internet for everyone to download. Later, everyone thought this little thing (Linux kernel) was quite small and exquisite, so slowly many friends devoted themselves to the research field of this little thing! But why are the little things here so great? ! But why can everyone download this thing for free? ! Hmm! When Brother Bird slowly bluffs xx ... Oh, no! Listen to me slowly!
An Unfinished Dream: Bell, MIT and GE's "Pluralistic" System
Early computers were not like personal computers today. It's not for ordinary people to touch. Only for military or high-tech purposes can you access this kind of computer! As mentioned above, computer hardware also needs the cooperation of the operating system to give full play to the efficiency of the computer. But in those days, because computers were regarded as "luxury goods", it should be said that they were "valuables", so a school might only have one mainframe. Of course, the so-called mainframe in those days still could not provide moderate computing power. However, since there is only one host, many teachers and students want to use it. What should we do? In order to solve this problem, Massachusetts Institute of Technology (MIT) developed the so-called "Compatible Time-sharing System (CTSS)" in the early 1960s. Literally, it is mainly to let the mainframe provide online access to the mainframe resources for multiple terminals (by the way, the terminals themselves had no software and no available resources at that time. If you want to use these terminals, they must log on to the host online before they can use the resources of the host to work! At that time, about 30 users could use the host online. In order to make this time-sharing system more powerful, Bell, Massachusetts Institute of Technology (MIT) and Singular Electric Company (GE) began to jointly develop a large-scale project called Multics around 1965, with the goal of enabling the host to connect more than 300 users. However, after four years of struggle, this plan still died ... oh! This is a failure! (Note: Multics means complex and numerous. )
Generation of Small File System: 1969 Ken Thompson's Small File Server System
After the failure of the complex Multics system project, Bell Laboratories of course withdrew from the project. Just after the project was dissolved, Ken Thompson, a member of Bell Research Laboratory who had participated in Muitics, needed a small operating system to access files because of his own work needs. 1969, based on the computer PDP-7 of digital equipment company, he designed a small file system suitable for his working environment, which also included some small tools developed by himself. That system is the source of the earliest Unix! When Ken designed this file system, he mainly designed a simple OS for his own convenience, so the original Multics system was greatly simplified. However, the term Unix did not appear at that time!
The formal birth of Unix: Ritchie and others wrote the first formal Unix kernel in C language in 1973.
Because the operating system written by Thompson is so easy to use, it has been widely circulated in Bell Labs and has been revised several times. 1973, dennis ritchie and others of Bell Research Laboratory rewrote the core of the original system of 1969 with C language with better compilation efficiency, and decided to name the operating system Unix, hehe! Is that the earliest Unix operating system? 1? 7? 1? 7! However, because this operating system was developed by this group of engineers, and most users are engineers in this field, it caused the situation that the Unix system interface was difficult to be accepted by ordinary users later @ @ (Note: Compared with Multics, Unix has a single meaning! )
An important branch of Unix:1the birth of BSD in 977
In the early development of Unix, there is a very important thing, that is the birth of BSD! Because C language is a high-level language and can be applied to different hardware architectures, Unix itself is written in C language! After Unix was published, Berkeley professors were very interested in this operating system. After obtaining the original code of Unix and several modifications, the first generation of Berkeley Software Distribution (BSD) was finally published in 1977. This BSD is a branch of Unix, and its development has a considerable impact on Unix. For example, Sun Company later developed the core with BSD.