What is Linux?

What is Linux? What is an operating system?
Before learning about Linux, you must know what an operating System is! First, let's think about it. When we use a computer, where does the screen show codoon? Well! It is displayed on the display card and screen. Now you can see this article on the Internet, it is a task completed by Internet, network card, network line, and all related electronic equipment and network equipment! What if you want to watch VCD? Therefore, the support of Optical Drive, optical disc, sound card voice and so on is required. In this case, everything at work is a work of hardware! Right! These computer hardware is working. How does the hardware work? That is achieved through the "Operating System! The operating system is communicating the message between your user and the hardware! That is to say, if you do not have an operating system, your computer hardware is just a pile of scrap iron and you cannot do anything!
What does the operating system contain? In short, the operating system is divided into two main parts, one is "core" and the other is "a bunch of core Tools". Let's make a simple description on Windows computers that users often use. Should everyone have used the File Manager in Windows? When you enable the archive manager, will it display the information on your hard disk? The information displayed in the hard disk is what the "core" helps you do. However, you need the core to display the information under the directory of the hard disk, this is done by the archive manager tool! Can this be understood? Again, if you have used Windows 2000 or Windows XP, it would be better! You should have heard of the so-called "FAT32 and NTFS file formats? In the early Windows version of Windows 98, he could not read or find a hard disk in the NTFS file format of Windows XP. Why? Because his "core" is not familiar with NTFS! Therefore, even if you have an archive manager, but you do not know NTFS at all, the archive manager cannot help you achieve what you want! Should this be clearer? That's right! Your entire hardware is managed by the core. If the core does not know your hardware, you will not be able to use this hardware device, such as the NTFS file format hard disk mentioned above! The core is "Kernel". It is the underlying thing of the operating system. It is responsible for controlling the operating status of the entire hardware resource. Linux has its own core, windows also has its own core. So when new hardware is added to your system, if your "Kernel" does not support it, this new hardware cannot work, because the Kernel that controls him does not know him! Do you understand this ?! First, let's have an overview. Later we will talk about "core compilation" in more detail!
In general, the management of Kernel includes:
System call interface: after some Services communicate with the kernel, the hardware resources are further utilized;
Process control: the system Process control center. The smaller the core, the better;
Memory management: controls the Memory management of the entire system;
File system management: File system management, such as I/O! There are also support for different file formats. If your core does not know a file system, you will not be able to use this file format! For example, Windows 98 does not know a hard disk in the NTFS file format;
Device drivers: As mentioned above, hardware management is one of the main tasks of Kernel. Of course, the driver of the Device is what the core needs to do! Fortunately, the so-called "loadable module" function is available now. You can edit the driver into a module without re-compiling the core! This will also be mentioned in subsequent core compilation!
So! All hardware resources are managed by him! As for our work, in addition to the features provided by the core itself (such as the File Manager mentioned above), we can also achieve this through other application software! For example, you want to watch a VCD video! In addition to the Media Player provided by Windows, you can also install the VCD player to play the VCD! This playing program is the application software, and this application can help you control the core to work (that is, to show the film), so we can say that, the core is to control the support of the entire hardware, and it is also the bottom layer of an operating system. However, to make the entire operating system more complete, it still needs to contain a wealth of tools provided by the core, and core-related applications!
OK! Speaking of this, do you know what Linux is? Haha! Yes! In fact, Linux is an operating system, which contains the most important kernel and the tools provided by kernel! He provides a complete architecture of the most underlying hardware control and resource management in the operating system. This architecture follows 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 transfer their work to this architecture, that's a lot of application software! Although Linux is only a tool provided by its core and core, due to the integration of the core and core tools with the software provided by these software developers, this makes Linux a more complete and powerful operating system! We can regard the relevance between the Linux System and the user as the following icon:

Figure 1 correlation between users, user interfaces and core tools, core, and hardware