356 Chapter 11 File Systems and Directories Direct access files are more complicated to implement, but are helpful in situations where specific portions of large data stores must be available quickly, such as in a database. File Protection In multiuser systems, file protection is of primary importance. That is, we don’t want one user to be able to access another user’s files unless the access is specifically allowed. It is the operating system’s responsibility to ensure valid file access. Different operating systems administer their file protection in different ways. In any case, a file protection mechanism determines who can use a file and for what general purpose. For example, a file’s protection settings in the Unix operating system is divided into three categories: Owner, Group, and World. Under each cate-gory you can determine if the file can be read, written, and/or executed. Under this mechanism, if you can write to a file, you can also delete the file.
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