Support for files is an abstraction provided by the operating system, and does not entail any real resource management. If disk space is available, it is used, else the service cannot be provided. There is no room for manipulation as in scheduling (by timesharing) orin memorymanagement (by paging and swapping). Howeverthere is somescope forvarious ways toorganize the data whenimplementingthe file abstraction. 6.1 What is a File? The most important characteristics are being named and persistent A file is a named persistent sequential (structured) data repository. The attributes of being named and being persistent go hand in hand. The idea is that files can be used to store data for long periods of time, and specifically, for longer than the runtimes of the processes that create them. Thus one process can create a file, and another process may re-access the file using its name. The attribute of being sequential means that data within the file can be identified by its offset from the beginning of the file. As for structure, at least one structure is typically required by the operating system
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