Operating System Services

Operating System Services

An Operating System offers services for users and programmes respectively.

• It offers an environment for implementing the services.
• It offers the services to users to execute the programmes in a convenient way. A few typical services are offered by an operating system-
• Program execution
• I/O operations
• File System manipulation
• Communication
• Error Detection
• Resource Allocation
• Protection

Program execution

Many kinds of tasks are performed by operating systems from user programmes to system programmes such as printer spooler, name servers, file server, etc. Any such operation is encapsulated as a process.

A process requires the full context of the execution (code to execute, deceptive data, registers, OS resources in use). Then observe the main programme activities of an operating system-

• Loads a program into memory.
• Executes the program.
• Handles program's execution.
• Provides a mechanism for process synchronization.
• Provides a mechanism for process communication.
• Provides a mechanism for deadlock handling.

I/O Operation

An I / O subsystem consists of I / O devices and associated driver software. Drivers mask the peculiarities of individual users hardware devices.

The communication between user and device drivers is controlled by an Operating System.

• Operation I / O means read or write service for any particular I / O device or file.
• The operating system gives the necessary I / O device access when needed

File system manipulation

A file contains a set of information relating to it. For long-term storage purposes computers may store files on the disk (secondary storage). Examples of storage media include magnetic tape, magnetic disk, and optical disc drives such as CD, DVD. Each of these media has its own characteristics such as speed, size, data transfer rate and methods of data access.

For easy access and use a file system is usually organised into folders. These directories can include files, as well as other directions. Following are the main file management operations of an operating system-

• You need to read a file, or write a file.
• The operating system gives the software permission to run on disc.
• Permission ranges from read-only, to read-write, to denied, etc.
• Operating System provides a user interface for the creation / deletion of files.
• Operating Framework provides a user interface for building / removing directories.

Communication

The operating system handles communications between all processes in the case of distributed systems that are a series of processors that do not share memory, peripheral devices or a clock. Inside the network, several processes interact with each other across communication lines.

The OS manages methods for routing and communication, and the contention and security issues. The following are the main communication tasks of an operating system –

• Frequently, two processes involve data transfer between them
• Both processes may be on one computer or separate computers, but are connected through a network of computers.
• Communication can be achieved using two methods: Shared Memory or Message Passing.

Error handling

Errors can occur anywhere, anywhere. Error in CPU, I / O devices, or memory hardware can occur. Following are the core operating system activities relating to error handling −

• The OS continuously scans for possible mistakes.
• The OS takes sufficient steps to ensure that the computation is right and reliable.

Resource Management

In the case of multi-user or multi-tasking environment, each user or job must be allocated resources such as main memory , CPU cycles, and file storage. Following is the main resource management tasks of an operating system −

• The OS uses schedulers to control all types of resources.
• CPU scheduling algorithms are used to allow efficient use of CPU.

Protection

Considering a computer system that has multiple users and several processes run concurrently, the different processes must be protected from each other's activities.

Protection refers to a method or means of controlling the access of programmes, processes, or users to computer system-defined resources. Following are the main protections tasks of an operating system-

• The OS maintains regulation of all access to system resources.
• The OS ensures external I / O devices are secured from invalid attempts to access them.
• The OS offers password-based authentication functionality for each user.