OS Services

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 Operating System Services:


1. **Program Execution**:

   - The OS provides an environment for users to conveniently run programs.

   - Handles memory allocation, CPU scheduling, etc., so users don't need to worry about them.

   

2. **I/O Operations**:

   - OS hides hardware details for Input/Output (I/O) operations, making it easier for users.

   - Ensures efficient and protected I/O operations, not controlled by user-level programs.

   

3. **File System Manipulation**:

   - OS manages reading/writing to files, relieving users from secondary storage management.

   - Simplifies tasks for user programs by handling file operations.

   

4. **Communications**:

   - OS facilitates communication between processes, whether on the same or different computers.

   - Relieves users from managing message passing between processes.

   

5. **Error Detection**:

   - Constantly monitors the system to detect errors, preventing system-wide malfunctions.

   - Relieves users from worrying about errors spreading and causing issues.


### System Calls:


1. **Definition**:

   - Interface between processes and the OS.

   - Allows user-level processes to request services not directly accessible to them.

   

2. **Purpose**:

   - Executes critical operations that could potentially cause system crashes if mishandled.

   - Standardizes requests for OS services, enhancing portability of programs.

   

3. **Examples**:

   - `open`, `read`, `write`, `close`: File operations.

   - `fork`, `exec`, `exit`: Process management.

   - `malloc`: Memory allocation.

   - `ioctl`, `socket`: Device and networking operations.


4. **Execution**:

   - Each system call has a unique identifier and parameters defining its behavior.

   - When invoked, the CPU switches to kernel mode, and the kernel performs the operation on behalf of the process.


These services and system calls are fundamental to the functioning of an operating system, providing essential functionalities and interfaces for user programs to interact with the system efficiently and securely.

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