The unix operating system is a multi-user, multi-tasking, interactive time-sharing operating system. It provides users with a simple, efficient and flexible operating environment. The UNIX system provides a good user interface, which is easy to use, fully functional, clear and flexible, and easy to expand and modify; the file system of the UNIX system is a tree structure.
#The operating environment of this tutorial: Unix system, Dell G3 computer.
UNIX is a multi-user, multi-tasking, interactive time-sharing operating system, which provides users with a simple, efficient and flexible operating environment.
Most Unix systems are written in C language, providing rich and carefully selected system calls, providing a powerful programmable Shell language (shell language) as the user interface, and using a tree file system It has good security, confidentiality and maintainability, provides a variety of communication mechanisms, adopts the memory management mechanism of process swapping and the storage management method of request paging to realize virtual storage management. However, Unix does not implement centralized management of network resources on a "domain" basis, which is a characteristic of Windows NT.
UNIX system occupies an important position in the history of the development of computer operating systems. It has indeed continued to meticulously, carefully and selectively inherit and transform existing technologies, and has made some progress in the overall design concept of the operating system, which has made it such a great success. The main characteristics of the UNIX system are reflected in the following aspects:
(1) The UNIX system is structurally divided into two parts: the core program (kernel) and the peripheral program (shell), and the two are organically combined into a whole. The core part is responsible for the functions of each module within the system, namely processor and process management, storage management, device management and file system. The core program is characterized by careful design, conciseness and leanness. It only takes up a small space and is resident in the memory to ensure the high efficiency of the system. The peripheral part includes the system's user interface, system utilities and applications, through which users use the computer.
(2) The UNIX system provides a good user interface, which is easy to use, fully functional, clear and flexible, and easy to expand and modify. There are two forms of use of the UNIX system: one is the operating command, that is, the shell language, which is the interface through which users can interact with the system through the terminal; the other is the interface for user programs, which is not only in assembly language, but also in Provide services to users in C language.
(3) The file system of UNIX system is a tree structure. It consists of a basic file system and several removable sub-file systems, which can not only expand file storage space, but also facilitate security and confidentiality.
(4) The UNIX system handles files, file directories and devices in a unified manner. It treats files as character streams without any records for sequential or random access, and enables files, file directories and devices to have the same syntax and semantics and the same protection mechanism, which not only simplifies the system design, but also facilitates user use.
(5) The UNIX system contains a very rich set of language processing programs, utility programs and tool software for software development, providing users with a fairly complete software development environment.
(6) Most of the programs in the UNIX system are programmed in C language, and only about 5% of the programs are programmed in assembly language. C language is a high-level programming language, which makes UNIX systems easy to understand, modify and expand, and has very good portability.
(7) The UNIX system also provides simple communication functions between processes.
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