Operating System Services

0:00In this lecture, we will study operating system services.

0:04So, we know that an operating system provides

0:07an environment for the execution of programs.

0:09And it also provides certain services to programs

0:13and to the users of those programs.

0:15So, in this lecture we will see,

0:17what are the services provided by the operating system

0:21to the programs and the users of the programs

0:25Alright! So, let's see!

0:26So the first one is the user interface.

0:29Now, this is one of the most important services provided by the operating system.

0:33Now, what is this user interface?

0:35The user interface is something that allows the user to interact with operating system.

0:43Almost all operating systems have a user interface.

0:47And the user interface can take several forms.

0:50Like the command line interface, also known as CLI,

0:53or the graphical user interface, known as the GUI.

0:57Now, examples of command line interface are like your command prompt,

1:00that you have in Microsoft Windows,

1:02or the terminal that you have in your Ubuntu based system.

1:05So in this command line interface, what you do is

1:08you provide text based commands using your keyboard

1:12in order to perform a certain task by the operating system.

1:15And the most commonly used user interface is

1:18the graphical user interface or the GUI.

1:21It is an interface where you have a windows system with a pointing device like a mouse

1:28then you have the menus and you can click those menus

1:31and also you can provide inputs using your keyboard.

1:34So, this is the most commonly used and the most user friendly interface that we have.

1:41So, this is the first and one of the most important

1:44services that are provided by the operating system.

1:46Now the next service that is provided by the operating system is

1:50program execution.

1:51Now, we know what are programs and what is software.

1:55So, the operating system must provide

1:57for the execution of the programs.

2:00That means you should be able to run or execute your programs and software.

2:05The system must be able to load the program into memory,

2:08and it should be able to run that program.

2:11So, this is also another very important service

2:13that should be provided by the operating system.

2:16Now the next service that is provided by an operating system

2:19is the I/O operation or the input/output operations.

2:22Now a running program that you have may require I/O, which may involves

2:27files or input/output devices.

2:29And this input/output operations should be provided by the operating system.

2:34A user cannot directly control the input/output devices.

2:39Now you may think that when you are using your keyboards, and mouse

2:43you feel like you are controlling it by yourself directly.

2:46But there is an operating system between you and your system,

2:50that actually controls the usage of the I/O devices.

2:54So, this I/O operation is also one of the most important operations

2:58that are provided by the operating system

3:00So, here I have shown you some example of input devices.

3:04Like keyboards, mouse and other inputs.

3:07And here you have the output devices.

3:09like your monitors, printers, speakers and so on.

3:13So, you have your operating system in between you, your programs

3:20and the I/O devices which help in the usage of these I/O devices properties.

3:25So, that is what we mean by I/O operations,

3:28which is also an important service provided by the operating system.

3:31Now the next service that is provided by the operating system is known as

3:35file system manipulation.

3:37So, this is also an important service.

3:39File system manipulation or file system management involves files.

3:44Now there are many files and directories in your system

3:47that have to be used.

3:48Now, the operating system must control

3:50how these files are manipulated or managed.

3:54Sometimes you may have to create, delete or modify,

4:02or sometimes you may have to search for a given file.

4:04So, all these are controlled by the operating system.

4:07And also it controls the permission that is given to certain programs or users

4:13for the access of certain files.

4:15So, all the files that you have

4:17cannot be allowed to be used by every program or by every user.

4:21There are access restrictions.

4:23So, this restriction of access is also controlled by the operating system.

4:28The another important service that is provided by the operating system,

4:32is file system manipulation.

4:35Now the next service that is provided by

4:36the operating system is communications.

4:39Now, from the name itself, you may already understand what is communication.

4:42We already know what is communication.

4:44But here what we mean is

4:47communication between processes.

4:50So, in the last lecture, I have already told you what is a process.

4:54So, a problem that is in execution is known as a process.

4:57Now, there are many processes that are present,

5:00and these processes often need to communicate with each other.

5:05So that they can synchronize with each other

5:07and their execution can be done in an efficient way.

5:11So, there are many circumstances in which one process

5:14needs to exchange information with another process.

5:17So, such communications may occur between processes.

5:21that may be executing on the same computer

5:23or between processes that are executing on different computers

5:27tied together by a computer network.

5:29So, the processes that we have

5:31may be present between the same computer

5:34and they may have to communicate with each other

5:36or may be connected by a network,

5:39and in this network they are connected to different computers,

5:42and there are different processes present in different computers.

5:45So, the communication between these processes

5:48between the same computers or even between the different computers

5:52is controlled by the operating system.

5:55So this is one of the important services that are provided by the operating system.

6:01Now the next service that is provided by the operating system is known as

6:04error detection.

6:06Now errors can always occur in the course of computing.

6:09And the operating system needs to be constantly aware of

6:12possible errors that can occur.

6:14So, there can be many kinds of errors that can occur.

6:16Like there are errors that can occur in the CPU.

6:19There are errors that can occur in the memory, and the hardware

6:22or there can be errors in the input or output devices.

6:25and so on.

6:26So, there are many kinds of errors.

6:27So, let me give you an example of an error,

6:29Here I have a printer and let's say that you are printing something

6:33and suddenly the paper runs out.

6:36Now, the printer is not able to print

6:38because there is no more paper available.

6:41Now, this is also an error.

6:43And the operating system must be able to handle this kind of error.

6:46So, that it ensures correct and consistent computing.

6:50Now what I mean by this is that

6:51when an error occurs your system must not just break down completely

6:55and it should not just seize your computing ability completely.

6:59The operating system must have a way

7:02in which it manages those errors

7:04so that your computing is consistent

7:07and it is still carried on even if some errors are encountered.

7:11So, error detection is a very important

7:13service that is provided by the operating system.

7:16And also sometimes you can have error correction or debug.

7:20So this is also an important thing provided by the operating system.

7:24It will make your computing more efficient.

7:27Now the next service that is provided by the operating system is known as

7:30resource allocation.

7:32Now resource allocation means

7:34allocating resources to different processes to different users.

7:38Now, what do we mean by resources?

7:40Resources can be of different types.

7:42It may be the CPU,

7:43It may be the files,

7:45It may be the input/output devices,

7:47It may be the main memory and so on.

7:49There are so many resources that you have.

7:51And as I told you there are many processes running in your system.

7:55And all the processes require certain resources at a certain point of time.

8:00Now, the operating system must help in resource allocation.

8:03It means that it should allocate the required resource to the processes,

8:07which are waiting or asking for those resources.

8:11And it must allocate them in an efficient way such that

8:15all the processes get the resources that they need

8:18and no process keeps waiting for the resource and never gets it.

8:22We should not have a scenario where a process keeps waiting for a resource

8:26but it never gets it.

8:27And also we should not have a scenario where

8:30a resource is held by particular process

8:32and it is never released.

8:34So, the operating system must manage how these resources are allocated.

8:39It should be allocated in such a way that

8:42all the processes get the resources that they need

8:45and computing takes place in an efficient manner.

8:48Now this resource allocation is a very important topic

8:51as far as operating system is concerned

8:53and we will be dealing with this in more detail

8:56in the course of this lecture series.

8:58Now the next service provided by the operating system is accounting.

9:02Now what we mean by accounting is that

9:04we want to keep track of which user use how much and what kind of resources.

9:11Now in the previous point I already told you

9:14what are computer resources.

9:15Now we want to know which user use how much and what kind of resources.

9:20And why is this required?

9:22This record keeping may be used for

9:24accounting or simply for accumulating usage statistics.

9:28So, by keeping an account of this

9:30or by having a statistics of this usage

9:32it can be a valuable tool for researchers who wish to reconfigure the system

9:37or to improve the computing services.

9:39So, if you want to improve your computing services

9:42you need to know how the resources are used and how they actually work.

9:46So for this purpose accounting is an important service.

9:50Now the next service provided by an operating system is

9:53protection and security.

9:54So by the name itself we can understand

9:56what we mean by protection and security.

9:58So, our data should be secure.

10:00And everything that we do must be protected.

10:04Now we can talk about these protection and security in different ways.

10:07First of all we can talk about it in the terms of processes.

10:11when several different processes are executing at the same time.

10:16It should not be possible for one process

10:18to interfere with the others

10:20or with the operating system.

10:22So the processes should not interfere with each others operation.

10:26And protection involves ensuring that

10:29all access to system resources are controlled.

10:32We already know what are system resources.

10:34protection means that access to the system resources must be controlled.

10:39And talking about security

10:40We can talk about security in terms of outside access.

10:44We should make sure that

10:46the system is not accessible to outsiders

10:49who are not allowed to access the system.

10:52So this is very common in our day to day lives

10:55when you used your computer system or when you used your accounts

10:58like your email accounts, or your social media accounts.

11:01You make your user id and password.

11:03And by doing that what you are doing is you are protecting your account.

11:07You are authenticating yourself by providing the right password.

11:13And only if you have provided the right password you can enter the system.

11:17And the security it extends to defend your external input/output devices

11:22like modems, and your network adapter and so on

11:25So you should make sure that

11:27these are prevented from invalid access attempts.

11:31And if anybody tries to access these devices

11:34without permission or in a wrong way

11:36then this invalid access attempt must be recorded

11:41so that you can improve your system

11:42or you can have knowledge that someone is trying to break into your system

11:46Now if a system has to be protected and secured

11:49then we have to take precautions

11:51from all the angles.

11:53that means throughout the entire system

11:56We must ensure protection and security.

11:59So, there is same which goes,

12:01A chain is only as strong as its weakest link

12:05It means that even if you are having a strong chain

12:08with which you are trying to secure something

12:10the strength of the chain depends upon its weakest link.

12:14So, even if you protect your entire system

12:17and you leave one area unprotected or

12:20one area not secure enough

12:23so that may be the link through which your system may be vulnerable.

12:27So protection and security have to be implemented throughout the system.

12:32So those were the important system services

12:35provided by the operating system.

12:36So, let us take a quick recap of all the points that we have discussed.

12:39We discussed about the user interface, program execution,

12:43input/output operation, file system manipulation

12:46communication, error detection, resource allocation,

12:50accounting, protection, and security.

12:53So these are the operating system services

12:56that are mostly provided by every operating system that we have.

13:01So, I hope this was clear to you.

13:03Thank you for watching and see you in the next one.