3. File-system manipulation. The file system is of particular interest. Obviously,
programs need to read and write files and directories. They also
need to create and delete them by name, search for a given file, and list file
information. Finally, some programs include permissions management to
allow or deny access to files or directories based on file ownership. Many
operating systems provide a variety of file systems, sometimes to allow
personal choice, and sometimes to provide specific features or performance
characteristics.