Directory creation and deletion support of primitives

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Directory creation and deletion. Support of primitives for manipulating files and directories. -File backup on stable (nonvolatile) storage media.
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SUSHMA RAWAL 23 I/O System Management The I/O system consists of: – A buffer-caching system – A general device-driver interface – Drivers for specific hardware devices
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SUSHMA RAWAL 24 Secondary-Storage Management Since main memory ( primary storage ) is volatile and too small to accommodate all data and programs permanently, the computer system must provide secondary storage to back up main memory. Most modern computer systems use disks as the principle storage medium, for both programs and data. The operating system is responsible for the following activities in connection with disk management: Free space management Storage allocation
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SUSHMA RAWAL 25 Networking (Distributed Systems) • A distributed system is a collection processors that do not share memory or a clock. Each processor has its own local memory. The processors in the system are connected through a communication network. Communication takes place using a protocol. A distributed system provides user access to various system resources. Access to a shared resource allows: Computation speed-up Increased functionality Increased data availability
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SUSHMA RAWAL 26 Protection System Protection refers to a mechanism for controlling access by programs, processes, or users to resources. The protection mechanism must: – distinguish between authorized and unauthorized usage. – specify the controls to be imposed. – provide a means of enforcement.
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SUSHMA RAWAL 27 Command-Interpreter System Many commands are given to the operating system by control statements which deal with: – process creation and management – I/O handling – secondary-storage management – main-memory management – file-system access – protection – networking
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SUSHMA RAWAL 28 Command-Interpreter System (Cont.) • The program that reads and interprets control statements is called variously: -command-line interpreter – shell (in UNIX) Its function is to get and execute the next command statement.
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SUSHMA RAWAL 29 Operating System Services Program execution – system capability to load a program into memory and to run it. I/O operations – since user programs cannot execute I/O operations directly, the operating system must provide some means to perform I/O. File-system manipulation – program capability to read, write, create, and delete files. Communications – exchange of information between processes executing either on the same computer or on different systems tied together by a network. Implemented via shared memory or message passing . Error detection – ensure correct computing by detecting errors in the CPU and memory hardware, in I/O devices, or in user programs.
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SUSHMA RAWAL 30 Additional Operating System Functions Additional functions exist not for helping the user, but rather for ensuring efficient system operations.
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