Okay.
Now let's dig into the next usage and explore some basic Linux command.
Now from here.
Open the terminal.
Now, from here.
If I go to the file preferences, go to the color scheme.
Here, you can change it to something else as you want.
Actually, I prefer green on black.
Now, not to sound like hair color, to be honest, but actually it's better for my eyes.
So if I click here.
Yeah, you can see that now.
It is better.
All right, actually, let's increase the font size control, shift the plus sign.
So, yeah, I think this is better.
It's increased this and this it.
Now the first command, it will be Alice, as it is the command used for listing the file.
So as you can see less and here all the files or directories I have on the current path so as to list
commands.
So I'll ask the list fight.
Okay.
Now we have clear.
So you can see that if I type enter.
And as you can see now, you can see that the screen is becoming chaotic.
So to clear the screen, we will put the clear command.
Clear, as simple as that.
Okay.
So we learned less and clear.
Okay.
Now, what if I want to learn more about specific command?
So for example, the last command, I want to read more about it, about its option, about its features,
whatever.
So we will use the main command.
The main command is used to, for many, one.
So man less.
It will show us what is the LZ command will do.
So let's directory contents as you can see, LZ.
This is the syntax or synopsis plus option.
Whatever options, then the file, whatever file.
So you can see that we have a lot of descriptions dash a, all the P, C, F or T and you can read more
about it as you can see from here.
Now to quit from this.
You can see that for help or for quit.
So let's quit.
All right.
So men clear, as you can see.
Clear the terminal screen.
And it has a lot of options that T type V, X, whatever.
Q to quit now, man, man.
So this is to show the manual for the manual page.
Okay.
So this is man, this is an interface to the system reference manual.
So you can see that it has dash k, dash k, capital dash FLW options, right?
All right, cool.
So far so good.
Okay, now if I type less, you can see that I am here currently.
I want to know where I am currently.
So if I type b w dx which is print working directory, it will show us that I am inside the home slash
kelly.
Okay, so if I type man P.W. De here, you can see that it will bring the name of the current working
directory.
Okay.
So Brent working directory or the current directory and it has a lot of options like Dash L, Dash P,
whatever.
You can read more about it.
Now let's clear the screen again.
And now if I type ls you can see that I am here inside the home.
Kelly When I typed BW D OC the Kelly Home Directory, now I want to go to the desktop OC where it is
here.
OC how to do such a thing.
I would use the CD Command Man CD again.
You can see that some of the comments are not or don't have manual.
So like the CD because it's a simple command so it has not so CD.
Then the name of the directory.
So if I type, unless I want to go to the desktop.
Okay.
But remember in Linux, this is a case sensitive.
So CD desktop, the D must be capital.
Now you can notice that if I type desktop, I can press the tab button.
So if I press it, it will autocomplete the sentence or the name of the folder or directory in Linux
we call the directory not folder.
In Windows we call this folder.
So CD desktop.
Now you can see that.
Yeah.
From here from tilde mark.
It changed to the desktop by the way, the tilde marking the tilde mark here means it is the home directory
of the current user, which is in our case it is the carrier user.
No worries.
We will talk about this in details later on.
But for now, follow me.
Okay.
Now, if I want to go back, I will go see the dot dot OC.
Now dot dot means the parent directory.
Again, we will talk about this later on.
No worries.
So here we will go back to the parent directory of the desktop and the parent director of the desktop
is the home directory of Linux user.
Okay.
Now, here.
What if I want to make a new directory?
I will use the command and data or make directory.
So man, make that and see this is to make directory and we have other options as you can see here.
So make dial and let's name a list.
And as you can see here it is test.
So seed to test.
You can see now we are inside the test directory.
Okay, so far so good.
Now, you may ask me, this directory is empty.
How did we go to the dot or to the dot?
There is other thing called that, which is the current directory.
How did we go there?
It is not even exist.
No, actually it is exist.
But it is hidden.
So if I type ls dash a this will show all the directory.
So how did I know that?
Just open the manually, page and press don't ignore entries.
Start with dot as you can see because the dot here in Linux it will be considered a hidden directory
OC or hidden files.
So when I type, it will not be shown, but it will show everything which is dot and dot dot the dot
here one single dot, which is the current directory which is the test directory.
Now you may ask me, but what is the use for this?
This is has this has no meaning.
No.
We will talk about it later on.
No worries.
And the dot dot, which means the parent directory of the current directory, which is the parent directory
of test, which is in our case, the tilde.
And we already mentioned that this means the home directory of the current user, which is clearly user,
which is the Cally home page.
So said dot dot.
It will go to the parent directory and you can see we returned back.
All right.
So far, so good.
Now let's clear the screen.
Now, also, there is other options like dash p.
Which means create a parent directory.
So, for example, I have this here, right?
So what if I want to create this tool, as you can see and inside it, I want to create a list three
like this.
This will not work because this tool is not exist in the first place.
So for that case I will put the P, which is parent and this will create this tool.
As you can see if I type ls this tool with directory it will show us the content or the yeah.
The content of this tool which is history, the folder we have created.
Now let's talk about another command which is the wish command.
This is to search through the directories that are defined in the bath environment.
So if I tap echo, this is a command used to print a text.
So if I type eco hi, it will print hi.
As you can see in double quotation.
If I type eco hi.
Also it will print it.
But if I type.
Echo.
Shift.
Hi.
Now you can see that the shift for the dollar sign means that this is a variable in Linux and this variable
is not assigned.
But we have environment variables called the best here.
So if I type it, it will see.
You can see that this variable contains a listing of directories that can be search when a command is
issued without its bath.
By the way, this is not in Linux only.
This is used with Debian or Linux generally.
So Debian based or IT based or whatever.
Linux distribution.
Well, some of them doesn't use this or have a special meaning, whatever.
But I'm talking about the popular or the popular distribution anyway.
So if I type ls here, you can see this is a command, by the way.
By the way, this is a utility that exists on the system that should be inside here.
So if I type eco path, it should be either here, use a local spin or use a local bin or user a spin
or whatever.
Okay.
So it must be inside one of these directories.
So if I type which by the way man which we learn that which locate a command as you can see, it will
look at the command where it is.
So which ls.
As you can see SE is easiest to lose dash color or which CD.
You can see that these are a built in commands.
So let's look about another command.
So for example, which python button is a command and you can see it is inside the user bin button here
where it is located.
So I'm using which command, by the way, the CD and LZ.
These are a built in command.
So most likely they are not existed anywhere or they are existed, actually.
But we will talk about these later on.
No worries.
Now we have another command called Locate Man, Locate like this.
This is to find files by name quickly.
So as you can see in which to read the database made by update DB.
So for example, locate python.
You can see it will start looking for all or anything called Python.
As you can see now this list to be updated.
We must use this command update db.
Like this, so press it.
You can see permission denied for that case because after all, I'm updating the whole system or I'm
updating the database from the whole system.
So I must use the sudo command.
No worries.
We will talk about this later on the the command, by the way, if I type man sudo this is to execute
a command as another user.
So sudo update db.
And here it will ask for a password.
Of course.
Which is catty.
One, two, three, four, five, six.
By the way, this is a stupid password.
But anyway, this is just for the sake of discourse.
Now we updated the database, so look it again by phone.
And sorry, I mistake this.
I have a mistake.
Yeah, it will show us the same result.
By the way.
Okay.
Now finally we have another command.
I know we took a lot of time, but these are just the basics.
No worries.
We will have what we learned practically step by step, and we will repeat it over and over.
So you will get used to it and you will master it in no time.
Trust me.
Now, finally, we have that find command.
So men find.
This is to search for file in directory or hierarchical.
So for example, find slash.
This is where we want to search the name and the name which will be by phone, for example.
But you can see that it will start showing us permission denied.
Permission denied.
All right.
So we learned that we already learned what we do.
What should we do?
Which is using the pseudo, as you can see.
It will show us that it found some.
But here we got permission denied for this for some reason.
For now, we will not handle it because this is a low level.
We will talk about it later on.
Okay.
So we found what we want.
All right, cool.
So far, so good.
Now I will provide you with exercises.
On what we have learnt here in this lecture.
So you will practice with me.
Now I recommend you to do the exercises because it will be very useful for you.
As they say, practice makes perfect.