1 list and briefly describe the key services provided by an operating system

An operating system is an interface which provides services to both the user and to the programs. It provides an environment for the program to execute. It also provides users with the services of how to execute programs in a convenient manner. The operating system provides some services to program and also to the users of those programs. The specific services provided by the OS are off course different.

Following are the common services provided by an operating system:

1. Program execution
2. I/O operations
3. File system manipulation
4. Communication
5. Error detection
6. Resource allocation
7. Protection

1) Program Execution

• An operating system must be able to load many kinds of activities into the memory and to run it. The program must be able to end its execution, either normally or abnormally.
• A process includes the complete execution of the written program or code. There are some of the activities which are performed by the operating system:
  • The operating system Loads program into memory
  • It also Executes the program
  • It Handles the program’s execution
  • It Provides a mechanism for process synchronization
  • It Provides a mechanism for process communication

2) I/O Operations

• The communication between the user and devices drivers are managed by the operating system.
• I/O devices are required for any running process. In I/O a file or an I/O devices can be involved.
• I/O operations are the read or write operations which are done with the help of input-output devices.
• Operating system give the access to the I/O devices when it required.

3) File system manipulation

• The collection of related information which represent some content is known as a file. The computer can store files on the secondary storage devices. For long-term storage purpose. examples of storage media include magnetic tape, magnetic disk and optical disk drives like CD, DVD.
• A file system is a collection of directories for easy understand and usage. These directories contain some files. There are some major activities which are performed by an operating system with respect to file management.
  • The operating system gives an access to the program for performing an operation on the file.
  • Programs need to read and write a file.
  • The user can create/delete a file by using an interface provided by the operating system.
  • The operating system provides an interface to the user creates/ delete directories.
  • The backup of the file system can be created by using an interface provided by the operating system.

4) Communication

In the computer system, there is a collection of processors which do not share memory peripherals devices or a clock, the operating system manages communication between all the processes. Multiple processes can communicate with every process through communication lines in the network. There are some major activities that are carried by an operating system with respect to communication.

• Two processes may require data to be transferred between the process.
• Both the processes can be on one computer or a different computer, but are connected through a computer network.

5) Error handling

An error is one part of the system that may cause malfunctioning of the complete system. The operating system constantly monitors the system for detecting errors to avoid some situations. This give relives to the user of the worry of getting an error in the various parts of the system causing malfunctioning.

The error can occur anytime and anywhere. The error may occur anywhere in the computer system like in CPU, in I/O devices or in the memory hardware. There are some activities that are performed by an operating system:

• The OS continuously checks for the possible errors.
• The OS takes an appropriate action to correct errors and consistent computing.

6) Resource management

When there are multiple users or multiple jobs running at the same time resources must be allocated to each of them. There are some major activities that are performed by an operating system:

• The OS manages all kinds of resources using schedulers.
• CPU scheduling algorithm is used for better utilization of CPU.

7) Protection

The owners of information stored in a multi-user computer system want to control its use. When several disjoints processes execute concurrently it should not be possible for any process to interfere with another process. Every process in the computer system must be secured and controlled.

An operating system executes programs and makes the process of solving them easier. It also makes the computer system easier to use and helps the user use the computer hardware efficiently. Apart from these, it also provides an array of services both to the users and the programs.

Services of Operating System

The OS is the resource manager of a system. Thus, there are multiple services it provides in order to have an efficient system that can utilize these resources to the fullest. Following are the services provided by operating systems:

1. User Interface

An interface is required to communicate with the user. Then it can either be a Command Line Interface or a Graphical User Interface.

There is also a third kind that is Batch Based Interface which is usually overlooked. It uses commands to manage the commands entered into files and then these files get executed.

As for the first two, Command Line Interface commonly uses text commands input by the users to interact with the system. These commands can also be given using a terminal emulator, or remote shell client.

A Graphical User Interface (GUI) allows users to interact with the computer system or any other computer-controlled device.

A GUI usually consists of all the graphical icons displayed on a computer screen, visual indicators like widgets, texts, labels, and text navigation. Thus, a user can directly perform actions with a click of the mouse or keyboard.

2. Program Execution

The OS loads a program into memory and then executes that program. It also makes sure that once started that program can end its execution, either normally or forcefully. The major steps during program management are:

• Loading a program into memory.
• Executing the program.
• Making sure the program completes its execution.
• Providing a mechanism for:
  1. process synchronization.
  2. process communication.
  3. deadlock handling.

3. File System Manipulation

A program is read and then written in the form of directories and files. These files can be stored on the storage disk for the long term. The OS allows the users to create and delete files, duplicate these files, and search files and their information or properties.

It also does permission management for these files i.e., allowing or denying access to these files or directories based on the file ownership.

4. I/O Operations

I/O operations are required during the execution of a program. To maintain efficiency and protection of the program, users cannot directly govern the I/O devices instead the OS allows to read or write operations with any file using the I/O devices and also allows access to any required I/O device when required.

5. Communication systems

Processes need to swap information among themselves. These processes can be from the same computer system or different computer systems as long as they are connected through communication lines in a network.

This can be done with the help of OS support using shared memory or message passing. The OS also manages routing, connection strategies, and the problem of contention and security.

6. Resource Allocation

When multiple users or multiple jobs run on a system concurrently, the resources need to be allocated equally to all of them.

CPU scheduling is used to allocate resources fairly and for the better utilization of the CPU. These resources may include CPU cycles, main memory storage, file storage, and I/O devices.

7. Error Detection

Errors may occur in any of the resources like CPU, I/O devices, or memory hardware. The OS keeps a lookout for such errors, corrects errors when they occur, and makes sure that the system works uninterruptedly.

8. Accounting

This keeps a check of which resource is being used by a user and for how long it is being used. This is usually done for statistical purposes.

9. Protection and Security

This is to ensure the safety of the system. Thus, user authentication is required to access a system. It is also necessary to protect a process from another when multiple processes are running on a system at the same time.

The OS controls the access to the resources, protects the I/O devices from invalid access, and provides authentication through passwords.

10. Command Interpretation

The OS understands and interprets commands that are input by the user and displays the input accordingly. Multiple command interpreters can be supported by an OS and they do not necessarily need to run in kernel mode.

If the interpreter is separate from the kernel then you can modify the interpreter and prevent any unauthorised access into the system.

11. Resource Manager

The OS manages resources such as processor, memory, I/O devices etc efficiently. It allocates resources to processes and administers running programs to ensure user satisfaction.

It also decides the time at which a program should run, the amount of memory allocated for execution, where to save a file, and much more.

Apart from these basics, there are some more services the OS provides that are a part of resource management. These are:

a. Process Management
When multiple processes run simultaneously on a system, the OS helps manage them in order to enhance system performance. Apart from this, the OS also manages printer spooling, virtual memory, swapping, etc and CPU scheduling is used to allocate resources.

Major activities regarding process management are:
1. Creates and deletes processes.
2. Suspends and re-activates processes.
3. A mechanism for

• • process synchronization
  • process communication
  • deadlock handling

b. Main-Memory Management
This deals with the primary, secondary, and virtual memory and increases the amount of memory available for each process. In order to perform program execution, it is necessary to load the program into the main memory.

The OS ensures that there is enough memory for a process to execute and different locations of memory are being used properly for effective execution of processes.

During execution, the memory manager tracks available memory locations, where processes can be allocated or unallocated.

c. Secondary-Storage Management
Primary and cache storage are volatile memories thus, the data is lost once power is turned off.

Moreover, main memory cannot accommodate all data and programs so secondary storage is needed as a backup like tape drives, disk drives, and other media. This provides easy access to the files and folders in the secondary storage using disk scheduling algorithms.

OS manages free space on the secondary storage devices, allocates storage space to new files, schedules memory access requests, and creates and deletes files.

d. Network Management
The OS works as a network resource manager when multiple systems form a network or in a distributed system. The processors communicate through network lines called networks.

Today’s networks are usually based on client-server configuration where a client is the program running on the local machine requesting a service and a server is the program running on the remote machine providing a service.

Summary

The services offered by Operating System make communicating with the system easy and user-friendly. These services are:

1. User Interface
2. Program execution
3. File System Manipulation
4. I/O operations
5. Communication system
6. Resource allocation
7. Error detection
8. Accounting Protection and security
9. Command interpretation
10. Resource management

These services are what make the OS so popular. Nobody likes complicated things and the OS makes working with a system so simple with all its services and functions.

What are the key services provided by an operating system?

What are the 5 key concepts of an operating system?

What are five 5 key functions and features of an operating system?

What are the 4 key features of the operating system?