Understanding User Operating System Interfaces: CLI vs GUI

In this lecture, we will study the user operating system interface. Now, in the previous lecture, when we studied the operating system services, we saw that the user interface is one of the most important services

that is provided by the operating system. Now, what is a user interface? A user interface is something that allows the user

to interact with the operating system. So, in this lecture, we will see a little bit more about the user interfaces

and we will see what are the approaches that allow the user to interact with the operating system. Now there are two fundamental approaches

for users to interface with the operating system. Now, if you remember in the previous lecture, we talked little bit about this.

that there are two fundamental approaches for the user to interface with the operating system. The first one being the command line interface or CLI.

So, the first approach is to provide a command line interface Or a command interpreter, that allows the user to directly enter commands

that are to be performed by the operating system. So, this is the first approach in which we have something known as the command line interface or CLI.

also known as the command interpreter. In which the user have to enter the command, of the task that he wants to perform.

So, the command has to be enter in the CLI and based on the command the operating system will perform the task. So, in this process,

the user has to remember all the commands that he needs for performing a certain task. And then the second approach is

to allow the user to interface with the operating system, via a graphical user interface or GUI. So, the graphical user interface is the most commonly used

as well as the most user friendly kind of user interface. which you usually use in your day to day life. So, in a graphical user interface what we have is

we have your desktop, with your menus, and then using your mouse and pointing devices you can click on your menus

or using your keyboard you can enter something And in that way, you interact with the operating system. So, even while you are watching this video

you got here using your graphical user interface. So, these are the two fundamental approaches for the users to interface with the operating system.

Now, we will see a little bit more in detail about the command-line interfaces. And then we will take an example of how to perform a certain task

using the command-line interface in two different operating systems. So, I will show you an example in Linux operating system

and also in Windows operating system in order to perform a certain task. So, as I already told you the command line interface is also known as a command interpreter.

And what happens is that. Some operating systems include the command interpreter in the kernel. Now, what is a kernel?

The kernel is like the heart of your operating system. So, we will be discussing more about kernel as we move ahead in the series. You must know that in some operating systems,

the command interpreter is included in the kernel itself. Whereas others, such as Windows, XP, and UNIX treat the command interpreter as a special program.

So these are two points that you should remember that in some operating systems, the command interpreter is included in the kernel.

Whereas, in some operating systems, it is treated as a special program. Now, you must have already known about the command interpreters

in different operating systems. Like in your Windows you have the command prompt, also known as the CMD sometimes.

And in your Linux, you have a program known as terminal, which allows you to interact with the CLI. So, I will show you the examples later on.

Now, on some systems with multiple command-interpreter to choose from, the interpreters are known as shells. On some system, you may have multiple command-interpreters

from which you can choose. And the interpreter is known as shells. For example you have the 'Bourne Shell',

the 'C shell', the 'Bourne-Again shell' also known as 'BASH', you must have come across this B, A, S, H. which stands for the 'Bourne-Again shell',

and the 'Korn shell', et cetera. So, these are some examples of shells that you have. Now, the question is how does the command interpreter

actually perform the task, that you enter using a command. So there are two approaches in which the command-interpreter

actually executes the task. So, in the first approach, what happens is that the code for performing the certain task

is included in the command-interpreter itself. So, let's say that you want to perform a certain task. And the task could be anything.

There are many tasks that you can perform. Like creating a file, deleting a file, copying, or moving a file

renaming a file, or executing a file, and so on. There are many kinds of tasks that you may want to perform. Now, let's say that you want to perform a task of creating a file.

Now, in the first approach, we said that the command interpreter itself contains the codes for performing a certain task.

Now, when you enter the command for creating a file, what happens is, the code for creating the file is

contained in the command-interpreter. So, that code will be executed from the command-interpreter itself when you try to create a new file.

Now, the second approach is that the command-interpreter itself does not contain any code, but the codes are written in certain programs.

So, there are certain programs which are responsible for performing certain task. And the command interpreter just called the program

based on the command that you enter. So, the command interpreter itself does not understand or does not know how to execute the command that you enter.

So, let's say that you want to create a file So, in the second approach, you enter the command for creating a file. The command interpreter is not going to run the code from itself,

because it does not have any code itself. So, what it will do is. It will call the program, which is responsible for creating a file.

So, that is how the second approach work. So, in the first approach, the code is contained in the command interpreter itself.

And in the second approach, the codes are contained in certain programs and the command-interpreter just calls the program,

when a certain task has to be performed, when the command is entered. So, that is how the command-interpreter works.

Now, I will show you an example. of using the command-interpreter or the command-line interfaces in two different operating systems.

So, let's say that we have a small task of creating two directories and also we want to delete those directories after we created them. So, I will be showing you how we can use the CLI

in Linux mint. And, also how we can use the CLI in Windows to perform these small tasks. So, here I am on a Linux main operating system,

Which is a UBUNTU based operating system. And, as you see this is the desktop of my Linux mint. And now we will see,

how we can use the terminal in order to interact with the shell and perform a certain task. And, let's say that the simple task that we want to perform is

to create a directory on this desktop, and then to delete that same directory. So, first of all, you have to open your terminal.

So, in order to open your terminal, you can press Ctrl+Alt+T on your keyboard. And, then when you pressed that, the terminal gets opened up for you.

which looks something like this. So, here the first thing that you see is your user name, followed by your computer name, or your host name,

after this '@' symbol. So, the first thing that we need to do here is we need to go the desktop.

Because we are going to create a directory on our desktop. And, right now we are not on the desktop. So, in order to check where you are right now,

if you want to know your present location there is a command called 'pwd' which means 'print working directory'

So, if you press 'Enter', it will show you what is your current location. So here you are in '/home/neso'. And, you are not on the desktop.

So, we need to go the desktop. So, in order to go the desktop there is a command called 'cd', which means 'change directory'

and then you have to type desktop. And, when you press 'Enter', you now enter the desktop. Now, you can check again by typing 'pwd',

which prints your present working directory. And, here now you are on the desktop. Now, here we want to create a directory.

Now, in order to create a directory there is a command called 'mkdir', which stands for 'make directory'. and followed by space, you have to give a name of your directory.

So, let me just call it 'Myfile1' And, when I press 'Enter' the 'Myfile1' directory gets created on the desktop. Now, if you want to see, what are the contents on your desktop,

there is a command called 'ls', which means list. and if you press 'Enter', you will see that 'Myfile1' is present on the desktop. So, I can minimize my terminal and show you.

'Myfile1' is created on the desktop. Now, let's say that we want to create one more file in same way 'mkdir' and I call it 'Myfile2'.

So, if I press 'Enter' again and if I list out Myfiles again on the desktop, you see that 'Myfile1' and 'Myfile2' are created on the desktop. So, here we see 'Myfile1' and 'Myfile2'.

Alright! Now, we want to delete these 'Myfile1' and 'Myfile2'. So, in order to delete these there is an another command called 'rm',

which means 'remove'. And, followed by '-rf'. Now, this 'rm' is used to delete files,

And, if you want to delete directories, you have to give this extra command called '-rf' and then space and then you have to give the name of your file.

So, let's say, I want to delete 'Myfile1', which is the name of our file And, when I press 'Enter', 'Myfile1' will now be deleted. Now, if i try to list out 'Myfile' on the desktop by 'ls' command,

you see that only 'Myfile2' is present now because we have deleted 'Myfile1'. So, let's go and see on the desktop

'Myfile1" is gone, only 'Myfile2' is present. Now, you can do the same thing for 'Myfile2' as well. 'rm -rf Myfile2'

And if you press 'Enter' and if you list out, you will see that there is nohing on the desktop now. And both 'Myfile1' and 'Myfile2' get deleted.

So, that is how you can perform tasks using the terminals. So, this is just a simple example of using the terminal of Linux Now, let us try to perform the same task in Windows.

So, here I am on a Windows 7 operating system, and in order to do the same thing that we did in Linux In Windows what we have to do is,

we have to go to your start menu and type 'cmd' and click on 'cmd' which is your command prompt. And, this is the command-line interface for Windows.

So, what we are going to do is we are again going to create two directories, 'Myfile1' and 'myfile2' on the desktop.

and then we will delete them. So, first of all what we have to do is. We have to go to the desktop.

So, right now this is the location, which is 'C: \Users\ Neso> ' So, we have to go to the desktop, for that we will type the same command 'cd', which means 'change directory' and then desktop.

Now, when you press 'Enter', you entered the desktop. Now, in order to make the files or to create the directory, what we will do is,

we will use a command called 'mkdir, which means make directory, and then the name of our file. So, which i will call 'Myfile1'.

So, when you press 'Enter', you see that 'Myfile1' is created on the desktop. And, if you want to make an another file 'Myfile2', then use the same command. And, 'Myfiles2' gets created.

Ad, if you want to see the contents of the desktop, you can type 'dir'. In Linux, we use 'ls'. So, in windows, you will be using 'dir'.

So, if you press 'Enter', you can see these are the files present on the desktop. 'Myfile1' and 'Myfile2'. which are these two.

And, 'New folder' is the one, which is already present from before. Alright! Now, we want to delete 'Myfile1' and 'Myfile2'.

So, for that, we will use a command called 'rmdir'. which means remove directory. And then followed by the name of your directory

that is 'Myfile1'. So, if you press 'Enter', you can see that 'Myfile1' gets deleted. And if you want to do the same thing for 'Myfile2'.

You can type 'rmdir Myfile2'. So that 'Myfile2' also gets deleted. So, that is how you use the command prompt,

in order to do the same thing that we just did in Linux. So, if you want to do the same thing using graphical user interface it's very easy, you already know how to do it.

just right click, go to New, and go to folder. And give the name of your folder and then your directory gets created. So, it's very easy how to do using graphical user interface,

you almost do it everyday, in your day to day life. And, if you want to delete it, its very easy, just right click again, and go to delete,

and then it gets deleted. Or you can just select it and press 'Delete' on your keyboard, And in that way also it gets deleted.

So, that is how user friendly and easy it is to use graphical user interface. And, we have also seen how to do the same thing using command-line interface. So, in those examples we saw how we can use the command-line interface

to perform certain task in Windows as well as in Linux. And also we saw a small demo of the graphical user interface. So, I hope these examples helped you to understand

how the user actually interacts with the operating system using this user operating system interfaces. So, I hope this was clear to you.

Thank you for watching and see you in the next one.