Operating System Services

Operating System Services

• Operating system provides different types of services to different users. It provides services to program like load of data into memory, allocating disk for storage, files or directory for open or read etc.

• Services will change according to the operating system. May be the two different operating system provides same type of services with different names. OS makes programmer job easy by providing different services.

Following are the list of services provided by operating systems :

1. Program execution               2. Input-output operation

3. Error detection                     4. File and directory operation

5. Communication                   6. Graphical user interface.

1. Program execution: Before executing the program, it is loaded into the memory by operating system. Once program loads into memory, its start execution. Program finishes its execution with error or without error. It is up to the user for next operation.

2. Input- output operation: Program is combination of input and output statement. While executing the program, it requires I/O device. OS provides the I/O devices to the program.

3. Error detection: Error is related to the memory, CPU, I/O device and in the user program. Memory is full, stack overflow, file not found, directory not exist, printer is not ready, attempt to access illegal memory are the example of error detection.

4. File and directory operation: User wants to read and writes the file and directory. User wants to search the file/directory, rename file, and modify the file etc. user also create the file or directory. All these operation is performed by user by using help of operating system.

5. Communication: Communication may be inter-process communication and any other type of communication. Data transfer is one type of communication. Communication is in between two process of same machine or two process of different machine. Pipe, shared memory, socket and message passing are the different methods of communication.

6. Graphical user interface: User interacts with operating system by using user interface. All operating system provides user interface. Command line interface and batch interface are two types of user interface used in the operating system. In command line interface, user enters the text command for performing operation. Batch interface uses files. A file contains the command for various operations. When file executes, command output is displayed on the screen.

• All above services provided by operating system is only for single user. If suppose there are multiple user in the system, then operating system provides some Po additional services. These services are resource allocation, accounting, protection of data and security.

• Different types of resources are managed by the operating system. Multiple users require different resource for their execution. One type of resource may be required by two different users. So resource allocation is necessary.