File -System Interface
For most users, the file system is the most visible aspect of an operating system. It provides the mechanism for on-line storage of and access to both data and programs of the operating system and all the users of the computer system. The file system consists of two distinct parts: a collection of files, each storing related data, and a directory structure, which organizes and provides information about all the files in the system. File systems live on devices, which we explore fully in the following chapters but touch upon here. In this chapter, we consider the various aspects of files and the major directory structures. We also discuss the semantics of sharing files among multiple processes, users, and computers. Finally, we discuss ways to handle file protection, necessary when we have multiple users and we want to control who may access files and how files may be accessed.
• To explain the function of file systems.
• To describe the interfaces to file systems.
• To discuss file-system design tradeoffs, including access methods, file sharing, file locking, and directory structures.
• To explore file-system protection.
10.1 File Concept
Computers can store information on various storage media, such as magnetic disks, ...