Network Engineers Programme | Videos

language: EN

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All right, well, I can see everybody is in and we'll wait for you to come in as well.
Anyway, so meanwhile, as we do that, let's just take a very quick look at what we are
doing today.
And again, this is just the fundamentals.
So I'll just quickly fire this up.
As this is on Linux command line basics, as I said, we are almost seeing this as
the first look at Linux.
You guys are comfortable with it, so we'll probably accelerate through some of that.
However, there is something that I would like you to know, which is we can always work
on a system on our own.
But there are some ideas or concepts that should be clear for us to probably troubleshoot
when things go wrong.
So we look at the Linux fundamentals from the operating system concepts, just a super
quick history, understanding distributions, and then start working on the Linux command
line.
And as we work on the command line, the absolute fundamentals of the file system,
how it works, how do we interact with the operating system, what are the different
file types, many core commands that will work across most of the Linux distributions.
We're going to have a look at those.
Pretty much everything that we are doing will be done hands on.
I would be sharing with you some, just like a lab file as well, and the content of this
as well.
I would say the starting point on working on any operating system is just the absolute
basics in terms of the concepts.
And you guys have already been interacting with the operating system, so we'll just
keep it very, very quick.
The core here is that the core of your operating system is what we call as a kernel.
And we interface with this kernel, typically through a graphical interface or
through some sort of a command line or a shell environment.
As you guys already know, right now, Linux, we have fantastic graphical
interfaces available, also for administration, and at the same time, we have the shell
available.
If you go back in the day, yeah, I think the only thing available was a shell, I'm
saying, 20, 30 years ago.
Graphical interfaces were not so common.
Today, we have the choice of both.
There are a few things you can literally do more efficiently only through the shell
itself.
Quick question, are you aware of different types of shells?
Not on my site.
No.
I think the comparison that I could have is that if you go to Windows, for instance,
we have one graphical interface, right?
Like one environment, one type of graphical interface.
And then you open a command prompt, that's your command line, maybe a power shell.
Linux Unix systems are known for flexibility.
So you can have different types of graphical environments.
And we also have different types of shells.
And they give different capabilities or different feature sets, for instance.
So it's just nice to know that when we look at the OS concepts, that there are
different types of graphical environments and shells available.
Typically, when we use a platform like Ubuntu or any other platform, we can
customize some of this during the installation as well.
So today, when you work on a shell, you're working on a certain type of shell.
When you're looking at a graphical interface, it's a certain type of
graphical interface.
And that depends on what type of Linux distribution you are working on.
On a fundamental level, the shell is your interface to work with the system
through the kernel, which is your absolute core.
Maybe the very first thing we want to do is just get started having a terminal
in our environment.
Maybe we can do exactly that.
You can see that in the online lab environment as well.
But let me just share exactly that.
Since you all are users of the Linux as well, what's the quick
shortcut to open a terminal?
Keyboard shortcut.
Let's try Control-Alt-T and get a terminal up and running.
Let's give that a try.
Control-Alt-T.
Let's just get a terminal up and running.
We like shortcuts.
Shortcuts are good.
Many ways to get the terminal up and running.
Let's try the keyboard shortcut.
I can see Paramount has got it up and running.
Control-Alt-T.
Yeah.
We have the terminal up and running.
And Austin, yeah, is up and running with the terminal as well.
Of course, the other way to get a terminal up and running,
you can right-click on many of the Linux distributions.
You can do that.
You can just right-click the desktop, open a terminal.
And I can also maybe go into my applications, the menu,
and search for terminal.
I see another terminal here.
Here we go.
So I have three terminals up and running.
But they're all started in a different manner.
One with the help of a shortcut, the other one
with the right-click on the desktop,
and the third one from the menu.
Can I request you to do the same, please?
Let's fire up three different terminals through the menu
from the right-click and from Control-Alt-T.
On the menu, where do I go?
So in the menu, you can just type to search.
Easiest thing to do would be to just type terminal.
And you might see this terminal,
made terminal for this GUI available there.
You might see multiple types of terminals.
We'll look into that.
OK, got it.
Thanks.
But you might see, again, depending honestly
on the different Linux platforms,
they might be in different places.
They might be arranged and organized under System Tools.
You can see here.
And then when in doubt, just search.
It's the fastest way of getting into the terminal
itself.
So in other words, we are working in a terminal.
This is a cell which provides us access into the OS.
And then we can do all kinds of things from here.
And as I said, once upon a time,
a terminal was the only way to work.
So as we work on that, quick question.
What are our privileges in the operating system right now?
Just by looking at the terminal,
what are our privileges into the operating system?
What does that dollar indicate on the shell?
You can take a guess.
Please don't worry about right or wrong.
You can just take a guess.
OK.
Is it not read and write?
So a dollar?
Yeah, go ahead, please.
Yeah, as in, OK, as I go with the read, because.
I understand what you mean by read.
And execute.
Yes.
I can execute a command.
So you can execute commands on all the terminals.
However, you are a normal user.
You don't have what we call as the root privileges.
In other words, you're not the administrator.
So certain commands that require admin privileges
just won't work.
You are a normal user.
If you have root privileges, what does the terminal look like?
What does the prompt look like?
What changes?
So let's try that on one of these terminals.
We have three terminals in front of us.
I'll explain the commands, of course, as we go in.
I'm going to do sugo bash.
No.
I can't do sugo.
If I do sugo bash, and I'll explain the logic in a bit.
I want you to notice if your terminal changes,
the prompt, the last character changes.
I believe it changes into a hash.
Would you please try the same?
sugo bash.
So now we have one terminal where
we have all the privileges.
And current other terminal is running under limited privileges
as a normal user.
Sorry, are we doing that on all of those three terminals?
Just one, please.
Pick one.
Oh, just one of them, OK.
Just to show the difference.
Just visually how it looks.
Does that work, Austin?
I believe it does.
Yes, it did.
Yes, it did.
Austin, there is a way.
Yeah, go ahead.
Oh, no, just saying that I have to find teams to unmute.
There's some open list, so it might be a little bit delayed.
Yeah, so you wanted to say?
No, what I'm saying is there is another name for a terminal
where you have root privileges.
Do you know the name of that terminal?
What's the root privilege?
Yeah, it is called as the CV updater
because this is where you make a mess
and you start looking for another job.
With great power comes great responsibilities.
The moment you see the hash sign on a terminal,
think twice and do nothing.
What that means is we work as a normal user as much as we can
till we need to actually perform
some system administration.
We wear the hat of the system administrator
as long as needed, and then we get out of that
and back into the normal user.
Can I request all of you here just
to type exit into the terminal which is
running under root privileges?
OK.
What changes onto the prompt?
Can we go back to the last time?
Yeah, we are back to the safe job
because here you can't mess up everything into the system.
Probably the very first thing I want to tell people
is when you are working on the shell,
how to recognize if you have higher privileges or not.
And if you have higher privileges as root,
the prompt changes.
And maybe we ask ourselves a question saying,
do I really need those privileges for what
I intend to do on the system right now?
Or is a normal user enough for me to carry on my work?
We'll get more into the sudo and the other commands
a little bit later on.
But just wanted to bring that point across.
Are we clear?
Any doubts, questions, thoughts?
OK, I take that as a sign.
I'm going to do exactly the same.
I'm going to exit and just come back
to a normal terminal, which ends with that dollar.
Just a little bit very quickly on Linux.
I really don't want to turn this into a history lesson.
But I think it's worth mentioning this.
When we work with Linux, we normally
hear the word distribution, Linux distribution.
And fancy people use the word distro.
Which Linux distro are you working on?
What that fundamentally means is
that there are many flavors of Linux, as it is open source.
A lot of modifications have been done.
Linux has been adopted and adapted
for various reasons by different organizations
and individuals.
And all of these are considered
as different distributions.
Very popular distributions will be something like SUSE,
like Debian, like Fedora, Ubuntu, like we have.
There are many, many, many distributions around.
And each has certain advantages, disadvantages,
specific purposes that we have got.
First question, how do we know what kind of Linux system
are we working on?
What is the distribution?
What is the kernel that we have?
How would we know what that is like?
Let's give it a try.
Please try this out, as you see on my screen.
If not, let me just share it with you right away.
So I try this command lsb underscore release
dash a.
Should give you a little bit of information
what kind of distribution you're on.
lsb underscore release dash a.
Now, not to make your life a little bit difficult,
but different Linux distributions have their own
unique ways of getting things done,
which in simple English translates to the commands,
the way they work on one distribution
may not work the same way on the other.
It can be a little bit challenging
if you jump from distribution to distribution.
And you might say, oh, on one distribution
I used to do this command or this tool.
Yeah, there could be some differences
as you jump across them.
And there are certain things which are kind of common
across all the different distributions.
So maybe it's nice to know, hey,
what kind of distribution I'm currently on
in terms of the Linux operating system?
What is the distribution that I'm working on?
Can be quite handy as well.
Let's try some very basic things right now.
We mentioned I'm back to my terminal.
I will minimize the other terminals.
I'm happy with just one at the moment.
If you're gonna make your user experience
a little bit better, you can always zoom in a little bit.
I do the control with the plus.
Just to zoom in a little bit.
So yeah, just take one.
I'm struggling with audio.
Hang on, is everybody else able to hear me?
No, you go away and then you come back
and then it goes, finish off and then come back again.
Okay, yeah, well, that's not good.
I shouldn't be going away.
Let me just make some adjustments.
I've just moved into a new home like three days ago.
So still finding that sweet spot.
I think now it should be better.
Is the audio a little bit better now?
Yeah, much better.
For now, yeah, for now.
So you believe that I'm a network engineer.
No, you're in a new home.
Yeah, you went, you as owner trying to find a sweet spot.
Yes, I hope that the audio works just fine.
Oh, you said control plus.
Yeah, control with the shift and the plus, of course.
Yeah, that should help you zoom in a little bit.
Let me keep a ping up and running to the gateway.
Okay, one and three milliseconds.
No, sorry, GP, the same thing is happening now.
I see no challenges with my network connections.
It's got to be teams.
Okay, let's just see how it goes
because from my point of view,
I just see a very happy connectivity.
I'm able to ping remote network systems
with eight milliseconds and I have a one gig
on my upload speeds around 250 MB, so.
Sorry, I had to drop the handbag.
So it wasn't only was totally with audio.
We can just do one thing.
I'll just drop out and join back in.
See if that makes a difference.
Okay.
Yeah, always worth trying.
Let me just leave.
Okay.
Okay.
Did you guys zoom?
No, my stream doesn't do it.
How's it now?
Just wondering.
Yeah, it's good.
Let's go.
Going and then.
Even now?
Let's see if we go.
No, you can't work.
You can't put it on the same page.
Okay, so I'll keep talking
and you can just let me know if it works.
I don't know.
Is the mouthpiece next to your mouth?
Because now you sound far.
Okay, hang on.
We can always find a setup that works.
Wait a second.
Hey guys, sorry I just gave away.
What's happening now?
We're just testing out my audio.
It seems they have some challenges.
Yeah, still.
But you sound better now
than before when you came back.
So I think every time I have to do a couple of pull-ups
and push-ups and I come back.
And it's all good.
Is it better now?
Yeah, it is, it is.
All right, let's carry on.
And then again, just let me know on the chat
if there is any challenges with the audio.
We'll try a different setup.
But frankly, from the network perspective,
I don't see much in terms of the challenges.
Okay, if you're with me, let's carry on.
And let's head back to the shell that we are in.
So we'll continue on just discovering
a little bit more about our system.
And we do that.
Let's share my screen.
And I'm here, back here on my environment.
So we did this lsb-release-a
tells us we are on Ubuntu.
There is a specific release.
You can look at documentation.
Let's try uname minus a.
It gives kind of a scary output.
There is a lot happening there.
So what do we get from uname minus a?
It tells a lot about the system,
but more specifically,
helps us learn about which exact kernel
is running in the system.
That might also make a difference
to the way some commands execute
or what capabilities of the system are available to us.
From the basic command line perspective,
it shouldn't matter.
Interacting with the file system
and doing basic system administration,
that this doesn't really matter a whole lot.
Let's see if we can find out
how long our system has been up and running.
So we can try a simple command, uptime.
So what do you reckon that uptime is on?
So it hasn't been up and running for too long.
It was a seconds.
Minutes.
Hours.
Kindly try the same.
We try uname minus a,
give some details of the kernel.
We try uptime,
tells us how long the system's been up and running.
All of us will be almost identical.
So I've worked on systems
where the uptime goes in years.
Many mission critical systems
literally just don't go down
unless it's planned maintenance.
So we're just discovering a little bit
about our system.
What's the distribution?
What's the specific kernel release?
A kernel version?
How long the system's been up and running?
The architecture.
Just some basic commands about our system.
Just discovering it.
What's going on?
We might also, on most environment,
just like to quickly know
how the system is performing.
Let's give that a try.
Let me fire up my shell.
All right, this will be easier to share.
Just anything new for you till now?
A command that you haven't tried before?
Everything that you just did.
Okay, listen.
How about the others?
Just check the things you've tried before,
things you've never tried before.
Yeah, maybe for me that has been...
Let me share my screen again.
So a very typical command,
just to understand how the system is performing,
is the command top.
And as I said in Linux,
there are many ways to go about something.
Top is one of the common commands
that gives you a live snapshot of system's performance.
So if I just write top and press enter,
it kind of fills up your screen, runs constantly.
You can almost think of it
like the Windows performance monitor.
And we can see
which application.
This is a remote connection.
VNC is taking around 10, 11% of the time.
Of the CPU, the overall CPU utilization,
overall load of the system,
the number of tasks running,
amount of memory, how much is free.
This kind of gives you a quick snapshot into,
again, in troubleshooting.
Is there anything eating up the system's resources
at this point in time?
Top command itself has a lot of details.
If I press Q, it will quit the top command.
And I'll get back to my tab.
Give that a go.
Run the command top.
You see some summary of system utilization.
You can see, yes, go ahead.
What command is it?
Because I'm only seeing the-
The running command.
Top, T-O-V, top.
Just run top and press enter.
Thank you.
So we can see now which applications
are taking the most resources
or which processes are taking the most resources.
10, 12% of CPU utilization.
Our system seems to be okay.
It's doing all right.
Austin, you can try the same as well.
Top command itself has many things
that we can do with it.
Wait, didn't you just use top alone?
You already ran top.
No, I already ran it.
Oh, that's fine.
I got confused a bit there,
but that's like, oh, it's copied with us.
That's the unless you're only using
the environment you're saying.
We just ran the command top.
And if you press Q to quit,
this is for everybody else.
It will exit the tool
and you'll come back onto the command line.
All right.
A quick look at the very basic architecture
of Linux.
Commands obviously is one aspect of it,
but understanding the OS helps
in understanding what the commands do.
So as we saw earlier,
we have the operating system kernel
which manages the hardware resources
and we interact with the kernel.
So the kernel itself
is here.
It works with the drivers.
For example, when you run the command top,
basically you are asking kernel,
hey, please give me the details
of the running processes.
So that's what the command is doing.
The command is asking the kernel
and the kernel is going
and fetching all the detail.
As I did mention,
there are different types of shells available.
We have the original shell,
born shell, C shell, T shell.
There are so many different variants of these shells.
Typically most Linux environments have
what we call as a born again shell,
but it can be different from environment to environment.
And there are many different graphical environments
that the different Linux distributions you work with
will have possibly different graphical environments.
And the good part is potentially you can choose also
what do you like.
In terms of the architecture,
there are plenty of different system tools.
We're gonna try those tools.
Again, we will learn not only how to execute
one tool or one command,
but the power comes from connecting the commands together
and we're gonna have a look at that today.
Can I tell you this?
This is a very important slide.
And the first point is the most important.
Anyone coming from Windows,
if I ask you what is a file,
what's your answer?
Windows, when you think of a file,
what do you think about?
Something you can read or write in your book.
So you're thinking about data, right, Austin?
Yes.
Anybody else?
What's the file?
I can see you're unmuted.
We don't hear you.
So I think this is the thinking, right?
I see the bubbles up the hill.
Yeah, I know.
I wanted to answer, but I'm like,
it's not my people.
That's fine.
I encourage any and every response, it's fine.
No, I thought you were fooling around.
Yes, fair enough.
See, in Windows, we associate files with storage.
In Linux, that's a mistake.
Because in Linux and Unix,
everything is a file.
And I'll prove it to you as we work on the system.
Your hard disk is a file.
Your keyboard is a file.
Your memory is a file.
Your user account is a file.
The screen you are looking at is a file.
The terminal you're working in is a file.
And that can kind of make your head spin
a little bit when you come from Windows,
because you're like, hey, the file is for data.
No, here, a file is a pointer to a resource.
And it's a very broad open definition,
like a pointer to some sort of a resource.
The resource could be anything.
Let's give that a little bit of a try.
I'm gonna go to my network environment.
I'm back onto the shell, as you can see.
The very first thing I'm gonna do here
is try a very basic command, ls, take a list.
What do I see?
Well, I see some resources.
But I can't tell if this is a file or a folder.
There are many ways to take a list.
We're gonna try them all.
The command ls itself, just to showcase,
has many ways to doing things.
What I wanna do here first, let me try this command.
And it's a very interesting command that I'm writing.
tty, which terminal is this?
I hope you remember, we also have other terminals.
I've minimized them, I find them at the bottom.
And in the other terminal,
I'm going to say tty, which terminal is this?
And what we notice is, when I say,
hey, what terminal is this?
It gives me a location.
slash dev, slash pts, slash one.
It's literally a file system hierarchy.
So what the system is telling me
is that this terminal that I'm looking at
is represented as a file here.
And this terminal that I see on the left-hand side
is also represented in the system as a file.
Do you notice that there are different pointers?
This is number one, and this is number two.
Is that based on which one you opened first?
Yes, absolutely.
Just one question, just one question again.
I assume the one that you're on with the desktop
is the one that you opened by a desktop.
Is there a reason why it's named differently?
No, no, no, this is just numbering.
They're both dev, pts.
The type of terminal is the same.
How do you do that?
Also, I was just asking the question
of where is the slash desktop?
Ah, you have been defined.
Yeah, I was just a matter of identifying.
Oh, you're coming to it, okay.
Okay, no problem.
But anyways, the quick-shot answer is,
right now the prompt is reflecting
the current location you are in.
Oh, so that's another thing,
instead of pwd.
Yes, this is just, they are being very helpful to you
because they know we are all lazy people.
They're like, hey, guess what?
You are in that folder.
Okay, thank you, makes my life easier.
One of the most common mistakes in the Linux Unix world
is write command, but in the wrong location.
So they're kind of helping you out,
and we'll come to that just in a short bit.
Okay, one and two, we can see.
I do have my third terminal here as well.
I have zoomed everything else other than the terminal N,
and I do the same thing here.
What terminal is this?
This is terminal zero.
So there is some numbering starting from zero.
This is device zero.
This is device one.
This is device two.
Let me try something.
Let me try a very simple command.
I'm gonna say echo hello.
Any guesses what it's going to do?
It's gonna show hello to the screen.
So it literally just takes this input,
and the output is on the current device.
So hello comes out on my terminal.
What if I did
that,
and I said this, dev vts two.
What am I trying to do here?
I'm trying to put it in that vt.
Hello to input net file.
Or since we have two a file.
But is that file really a file,
how we think about it?
No, no it's not.
So what's gonna happen when I do this?
Where does the hello go?
I was in that directory.
Maybe just list everything.
Look, look here.
The hello showed up in the other terminal.
Wait, oh is it?
I just saw that now.
Can you guys try this out?
I just saw that you actually listed a different path.
I didn't see that it was on zero,
but it's still true, okay now I just saw that.
Can we try this please?
Send a hello from one terminal to another terminal.
Mention the file that represents that terminal.
And just writing tty will tell you
what is the identity of that terminal.
The example is in front of you.
Just give it a try.
Guys, I hope you don't mind us doing these things
because all of you have said
you are a bit comfortable with Linux.
So I'm just expanding beyond the little bit of comfort
that you have with Linux with some core concepts.
No, we are good.
You want us to follow you also?
Yes, yes, yes.
Okay.
So arrange your three terminals.
Find out their identity,
which file represents them.
And try the echo command, just as you see.
So we should redirect it to two,
even though I don't have it.
Oh, I can do one.
Yeah, any other terminal is fine.
So normally we just click right.
We right click when we want to paste something.
Does it work here?
Sorry, could you repeat that?
When we want to say you've copied something,
you want to paste it.
Normally we just right click.
So we need to find out for this.
We can distribute it as it works also.
You can try that out.
That depends on the terminal
and the type of terminal application as well.
All right, quick question.
Do we understand everything is a function
and file is not just data storage.
The very important in the Linux world,
even devices are files, physical or logical.
I might say Unix by mistake, but I mean same thing.
Basic principles are the same.
So we answer a very fundamental question.
What is a file?
And the answer is this.
So what we would like to know,
let's just bring this up one second.
So let's have a look at what is a file
and then we'll explore it in our operating system
exactly the same way.
I'm just gonna run the figure again.
Look at the file types.
Here we go, and let me just share.
So let's say we have a file type.
So files that contain data,
we call them as ordinary files.
Even folders are considered as files.
Then we have files that represent devices or drivers.
We call them as device files.
The example we saw right now was for terminal.
And we have like shortcuts in the Windows world.
We call them as links.
And we have different kinds of shortcuts,
soft links and hard links,
and we're gonna have a look at those.
So let's just see the file types
and have a quick look at the,
what we call as the directory structure.
Here is what we need to know
about the directory structure.
And I would say like this is the
starting point for your journey.
In the Linux world.
Let me share my whiteboard here with you.
And let's just take a closer look at the Linux file system.
And obviously the starting of the Linux file system
is what we consider as the root.
Don't confuse the word root.
Root can be a term used to describe the file system.
And root can be used to describe the user.
Who is the super user?
The super user is super chill.
Here we are referencing the root
in terms of our file system.
How things are laid out.
And the root of the Linux file system
is represented by that forward slash.
This is the top of the hierarchy.
Every resource in the system
is somewhere down there.
So for instance, under slash,
I see a folder ETC.
This contains all kinds of configuration files.
Similarly under slash,
I'm gonna see a lot of other folders.
And learning Linux is half learning this hierarchy.
What is where?
The important thing is what is the top of the tree.
Or the root depending on how you wanna look at it.
So if we go to our
live environment,
let's try some things out.
The very first thing we would like to do,
I'm just happy in any one of these terminals,
the very first command is writing PWD.
And I think many of you know that.
It means print my working directly.
Where am I?
The thing to note here is
what is the starting point on the left hand side
is that forward slash.
So under the root, there is the home folder.
Under that is the student folder.
This is where I am currently at this point in time.
If I write CD backslash,
this is literally going to the start of the file system.
Everything is under this structure.
And if I say, hey, print my working directory,
it says, well, you are at the start.
Everything is under this hierarchy.
So this is the root of the file system
and everything is under this root as a file system.
And part of learning Linux is learning navigation.
Does anyone know if I just write CD and press enter,
what will happen?
Here is a command.
Many commands would need a parameter.
What happens if this command, I don't give any parameters.
Change the directory, but I don't tell you where.
It doesn't do anything.
Just be the same directory.
It takes you to your home directory.
Okay.
Can you try out exactly what you see in front of you?
Go to the root CD slash.
Verify that you are in the root
with a print working directory.
Just write CD and press enter.
And you are magically transported to your home directory.
What character represents the home directory?
Look at your prompt carefully.
What do you call the character again?
For what it is called?
Can you guys still hear me?
Yeah, we can hear you.
Can you hear us?
Yeah, all well.
Because I was tweaking it.
I was just saying the character for what it is called.
Ah, tilde.
Yeah.
You know why I like Linux?
It makes you realize we don't know our keyboard.
You just know where to press it.
That's all that matters.
Never mind the memes.
Do you know the story of the Q-W-E-R-T-Y?
Why those characters are up there on the first line of the keyboard?
No.
If you pay attention,
you can type the word typewriter from the first line on the top.
So back in the day when typewriters were becoming popular,
they designed it this way so that the sales people could go and pitch to everybody,
look how quickly we can type on a typewriter.
And they would type typewriter and people would be impressed.
Scammer.
And people would be like, wow, yeah, that's so fast.
They didn't realize that typewriter could be typed just on a single line.
All right.
I hope this worked for everyone.
So the character tilde represents your home directory.
And P-W-D kind of tells you what is your current directory.
And what that means is when you're working on the command line,
you need to know three things.
Commands have parameters and options.
Let's take a look.
What do I mean by commands have parameters and options?
OK, I'm going to just share my environment just a little bit.
And we'll take a break shortly, I think around 15-odd minutes from here.
We'll just stick to your regular break size.
I'm happy to take any suggestions as well.
Here, a quick one.
So here is a command cal, prints out calendar.
Now in this case, it says, hey, you don't have calendar.
Here is a command date.
What does date give me?
Let me clear the screen.
Well, date does a lot beyond date.
It actually tells you time.
And what does the command time do?
Just a quick one on that.
So the time zone is takes it away from the system.
Yes.
The system, OK.
Yeah, it's got nothing to do with your time zone.
It's the time zone set during the installation of the system.
And in these cases, these are virtual machines running on a hypervisor.
So typically, they borrow it from the hypervisor.
So this would represent which part of the world the infrastructure is running on, for instance.
All right, so a very interesting operating system.
I say date.
It tells me date and time.
I run the command time.
It tells me something I don't understand.
With the command date, what happens if I do dash dash help?
Some of these helps are a few pages long.
But the important thing here is how it's supposed to be used.
So it's saying there is a date, and then you can mention the options.
Options can be short or options can be long.
But the important thing is the options begin with a dash.
And there are many options available.
So let's try something.
We're going to make sure you are in your home directory.
If not, just type cd and press enter.
You can obviously verify that, that you're in your home directory.
Let's try the command ls.
That gives us a list of resources.
And in my home directory, there is desktop, music, public picture.
Many of these look like these are folders.
But I would like to learn a little bit more about how to use the command ls.
I'll try some help.
I do a quick dash dash help.
A long list of help shows up.
Basically it tells us all the options available.
And as an argument, I can mention which folder I would like to see.
Or which file I would like to see more about.
Couple of interesting options that we see there.
Minus f, minus g.
Human readable, minus h.
So there are plenty of them as well.
We have the long list format.
I'm sorry, how did you zoom in on the terminal?
Control with the plus, with the shift.
Or plus with the shift?
Or with the view.
Okay, that is better. Okay, thanks.
First thing that you want to do is customize it.
So let me run the command ls minus l.
When you do ls minus l,
pay attention to the very first character.
This is a long list.
We are looking at the very first character.
So what does d represent here?
All of these are directories or folders.
In Windows you use the word folders.
Typically in Linux you use the word directory.
These are all folders.
Okay, let's very quickly create a file.
What is the command to quickly create a file?
Which has nothing in it.
The command to do what?
To create a file, an empty file.
It's mkdir.
That would make a folder.
I want to create a file.
Touch, touch and the name of the file.
Let's have a look at the long list again.
What's different about my file?
By the way, everything I'm doing,
I'm expecting you to repeat along with me please.
Right now?
Okay, what's different is the size and also the rights.
Look at the first character.
Yes, it doesn't have a d.
So that dash indicates an ordinary file.
Just a file that contains data.
Do you remember the file that represents a terminal?
ls minus l would give me the details of that file.
What is the first character?
It is not a minus, isn't it?
It's some other character.
And it's not a d either.
If it starts with a c or a b,
we call it as a device file.
A file that represents a device.
So the very first command that you probably would like to learn
when you're working on file system is simple.
ls minus l. What am I looking at?
Is it a folder?
Is it a regular file?
Is it some special kind of file?
Is it a link to something?
ls minus l gets us that answer.
For instance...
Yes, go ahead.
A device file.
There are characters and blocks.
What about the one with t?
A directory or a folder.
And a dash is an ordinary file.
I think, see, writing commands on Linux is not so difficult.
But understanding the logic behind it helps.
Makes us more comfortable with the platform.
Because Linux can be a bit complicated as well.
Alright, before we go any further,
just a quick check.
Are we all good so far?
There's Andre, Austin, Caroline, Faith.
Oh, Colorfula, we just saw you.
Sorry, just happy morning.
Yeah, I'm so good on my side.
Yes, what I wanted to know is that
dash dash help brings up what?
I know it brings up a lot of info,
but what would the show description be?
So yeah, so dash dash help.
You're asking what does it do?
Are you looking for something?
Yes, yes, no.
So dash dash help tells you about the command
and tells you about all the options
for that particular command.
Some of the commands, if you ask for help,
you get a book as a response.
And then we just Google the option.
They're like, I'm not reading this.
Thank you.
I'll just Google how to do something.
And of course, these days,
your deep mind will work just as well.
There are commands like tar
for which you can actually read a book.
Yeah, but it does give you help on that.
How about the other space?
Too much, too little.
We know all this.
I just need to know.
I'm here on my side.
However, I think maybe when we come back,
I just wanted to know more about the list
because I just wanted to know the difference
between the ls minus ltr and that one ls.
So different options.
And what happens when you combine different options?
We're going to have a look at that.
All right.
So maybe a good time for a short break.
How about 20 minutes?
I'm very generous.
No, no, I'm kidding.
15 is fine.
After lunch.
Now we have six.
All right.
Then a short 15 minutes break.
See you guys in a bit.
OK.
Thank you.
OK.
Cool.
OK.
OK.
Go on.
All right.
All right.
All right.
OK.
All right, back with all of you, if you're around.
All right, here we get a big thumbs up from Coloferlo.
Big!
All right, Carol Mung is back as well with the second cup of coffee, I assume.
Not yet.
You're saving it for later.
Yes, maybe in about 30 minutes, because I had it later, like half past nine.
We have to be careful with the caffeine dose, right amount, right time.
Yes, and the thing is, I don't drink coffee for the next three months.
So I'm not enjoying this tea, like coffee.
Of course you're not.
Sometimes I can live with it, without it, two hours or three hours away.
Any particular reason for giving up coffee for three months?
I'm on a diet.
They didn't know coffee was part of any of this, but good to know.
Yeah, you know, I don't know.
My dietitian said that.
The dietitian has to say something, right?
So they have to be creative as well.
They're like, what else can we ask this person to not do?
How about coffee?
Yeah, let's go with that one.
Yeah, no, I also don't trust her, but she's a producer.
She's the best in the game.
Welcome back.
Hopefully you survive without a bit of caffeine.
Yeah, no, I have my water here.
All right, that works.
I once gave a break and someone came back with a kale juice and I said, you win.
Anyone who can come back with a kale juice just wins.
I know.
They're on another mission.
It's a different level when you're on kale juice.
Faith, Lissandra, welcome back.
Hopefully you're around.
Hi, Mia.
I see Austin and Faith and Mute.
Hopefully they'll be back soon.
Just give them a few minutes.
So just talking about what we were doing earlier, as I said, I would highly encourage you to try things out along as well.
I once said to some group, Linux is not a spectator sport.
It's the easiest operating system to watch somebody else do things.
And when you do it, nothing works.
You know, uppercase, lowercase, spaces, and you're like, well, when that guy was doing it, everything was working.
What's going on?
So you do need to try it, to make your own mistakes and then learn from it.
Yeah, that's true.
I would encourage you to do the same as well.
OK, hopefully the others just join us just in a bit.
Let's see where we are at.
So we're looking at different file types as such.
Ordinary files start with a dash.
Directory starts with a D.
We saw the devices start with a C or there is a B as well.
And we will get into the links as well shortly.
We're just familiarizing ourselves right now with the directory structure as well.
And some of the basics on the commands as well.
And I think part of that is just over a period of time, you kind of create a memory map of which folders are important, why they are important.
And that's mostly true for administrative side.
If you're working in your own home directory as a user, working on something, we'll answer some of the questions in terms of LS and a few other basic commands.
First, let's just take a quick look at the typical directories.
I'm going to share my screen in just a bit.
All right, I'm going to get back to my terminal.
Let's share this.
So we looked at the root as such.
And we were looking at the command LS.
We were looking at the options of the command LS.
And I will dive into that shortly as we get back into the commands.
The important thing I wanted as a message to come across is the idea that you have commands.
We have options.
And we have parameters.
So in this case, LS is a command.
Minus L is an option.
I have a long list.
And then maybe the location.
Are you moving away again?
Sorry, can you hear me?
Very fast.
I can promise you I'm right where I was.
Let's just see if the audio.
No, no, I'm getting the same idea.
I can hardly hear what you're saying.
All right, so let me leave and come back.
Okay.
All right.
Let's see if this is any better than earlier or if it is the same.
It's definitely better for my end.
All right.
Let me also try another trick.
Wait, wait.
Okay, how about now?
It's soft, but I think we can hear.
I don't know if the other guys.
It's softer than the other guys.
Okay.
It's all right.
I can always try something to make it better in terms of the audio.
Could just be a setting in teams.
You can always give that a try.
All right.
I'll just keep on talking and just let me know.
If any better or worse.
Yeah, definitely better now.
All right.
Okay, since we are spending time on the command line, it kind of helps seeing what I'm doing.
All right.
So back to the idea of command options and argument.
LS is the command.
Minus L is the option.
And the root file system is the argument.
I want to see a long list of the root.
And I kind of get something like this.
We can also see here.
There are a couple of files that begin with an L.
This is the fourth type of file.
Shortcuts or what we call in the Linux Unix world as links.
Begins with an L.
So we have D for a directory.
We have dash for a regular file.
We have C or a B for devices.
And we have L for the links.
This is how you know what is the type of file you are looking at.
Just to take a quick note.
What happens if I swap this?
If I say LS slash minus L, would that work?
Command, argument, options.
Any guess?
Let's say it's argument, options.
Ah, okay.
It's time to go back in.
And guess what?
If you try the same thing on older Linuxes or older Unix environments, it just won't work.
So Linux has become friendlier and friendlier and friendlier.
For instance, you have some color coding in a terminal.
I don't remember seeing this in the 90s.
It was nothing like this.
So the operating system, especially Linux, is a bit more friendly than typical Unix,
which is a bit more hardcore.
And it is the way it is with very little flexibility.
Your comfort and ease of use was not the top priority.
But here it is.
Coming at the other files.
Go ahead.
Are you happy with the improvements?
Why not?
That's progress.
There's no need to be a snob about it.
So a lot of people will have that snobby attitude.
You know, the elitist, if you don't know VI, you are not a Unix guy.
And if you cannot compile the kernel, yeah, well, it doesn't matter.
Most of those people are irrelevant now.
This is getting the job done.
Understanding the architecture is always helpful, no doubt.
Especially in troubleshooting.
Austin, that's where I make a distinction between a user, an administrator and an engineer.
So user is just using the system.
Administrator is managing it.
An engineer understands under the hood.
And in the olden days, I really sound old saying that.
But you couldn't be an administrator if you were not an engineer.
If you didn't know how it worked.
These days, not so much.
You don't need to look under the hood.
You can just do the system administration without taking deep dives.
This just means more productivity from an organization perspective.
As far as you can produce faster, that's all that you can say.
So cloud automation, all of this is a result of that, right?
OK.
So we see a lot of folders here.
And again, we see slash home.
This was where the user's home directory was.
ETC is where a lot of configuration files are.
Almost like the registry of Windows.
MNT is where you get mount points, basically access to any storage or other volume.
My computer, C drive, D drive, and others.
We have the bin.
This is where the actual applications or executables are located.
And many others are where log files and other structures are.
Over a period of time, as I did mention earlier,
you get more and more comfortable with kind of what is where.
Just to show you a reasonable mind map of that.
It's not easy to memorize everything all at once.
The more you work with the system, you kind of figure out this location.
ETC is configuration.
Boot is where the kernel is.
Bin is where the typical executables are.
S bin is where the system administrative tools are.
And other locations, you kind of discover them over a period of time.
And this is more, again, for administrative purposes.
You kind of get used to them as well.
And then over a period of time, the more you use the system,
the more you start realizing what is where.
That's part of learning Linux and Unix.
That has not changed.
The exact structure of the file system could be slightly different
depending on the distribution and other variants within Linux world.
Fundamentally, it remains similar, but not always the same.
So yeah, there are certain directory structures that you can get.
Let's look at some basic commands.
But before that, also look at the how do you work with the files.
Let's go back to the commands bit.
And we start our journey very quickly with the command ls.
So here, take a list.
The implied argument is the current directory.
We saw dash dash help.
Minus r, give me a reverse order if I'm sorting.
l, give me a long list.
Because it's case-sensitive, it's not always the same parameters.
So minus i lowercase is not the same as i uppercase.
rst, I'm sorting by time.
The newest first.
This is my home directory.
Let's do this option. I can do it two ways.
I can separate the options out.
Minus l, minus r.
I can also just combine them together.
So a quick bit of help might come in handy.
And of course, there are detailed helps available, which we will get into.
This is what we call as the man page.
Basically man is short for manual.
And the man page is quite handy.
So any command typically you want, we can open the manual page for it for a quick reference.
What is the difference between the manual and the help?
Some commands don't have that detailed dash dash help.
Most would have a manual page.
And man page is literally like opening a book.
So it's easy to jump from topic to topic.
Dash dash help is just a quick output on the screen.
Man itself is a tool.
Yeah, would we be able to jump from topic to topic?
So if you look at the help for man, we will talk about this as well towards the end.
But man page itself has a lot of commands.
You can find what is related, the pattern search.
You can generate an index.
So there are many ways to use.
So man is a powerful tool all on its own.
So for example, while I'm reading the help, I can actually execute a command.
While I'm reading help.
So it is very interactive, very useful.
Maybe towards the end of the session, we'll have a quick look at man in depth.
Once we have seen all of these different commands,
we can see how man pages can be helpful as well.
It's almost the cornerstone of Linux, Unix environment,
which is going through the man page and looking for what you want.
Again, remember this is before Google and all that.
So it's just the built in into the system.
But man is big.
It's got a lot of commands built into it.
And it's not the only help system.
This is the code that you will find.
Man is something you expect in every Linux Unix platform.
We'll dive into man as well.
You'll see some examples of how it could be useful.
Maybe I'll give you some small challenges as well along the lines.
As we start to work within the file system,
maybe it's good to start with understanding paths
and what we mean by absolute path and relative path.
So let me explain that.
First thing, I recommend that everybody is in their home directory.
And let's create a quick file.
Let's create a folder.
Just a simple file that contains hello and an empty folder.
Right now, when I have mentioned the path of file one,
this is what we will consider as a relative path.
I have not mentioned the exact location of file one.
So the system assumes in the current location.
When I'm making a folder, also I've mentioned the system assumes current location.
The only reason for that is very simple.
And you need to pay attention to this one.
Any time you mention a path, if the path begins with that slash,
then it doesn't matter where you are in this question.
Your current location is not very important.
What matters is you are giving the system the absolute location based on the hierarchy.
You are mentioning the full location, the full path.
In other words, if I go here in my current directory,
one way to create a file is just say echo hello file one.
What if I want to do this is the absolute way.
I'm going to say echo hello.
But now I'm going to mention the absolute path.
That means starting from slash home slash file two.
The end result in this case is the same.
There is a file in my home directory.
The only difference is here where I mentioned file one, I did not start with the root.
This is relative to where I am.
And here I mentioned the exact location.
Any time you want to be sure about the location of file system object,
you can start with slash.
Then you know for a fact exactly where that resource is.
So for instance, right now, if I say I want to see what is in file one,
very simple command cat to catalog to read a text file.
And it works.
If I change my location to another folder.
And if I say cat file one,
that's probably not going to work unless there is a file called as file one in that folder.
It is able I don't know where that is.
I can always mention the exact path, the full path.
So in that case, my current location has no meaning.
What the path begins with.
So this is called as absolute path.
And there are many other ways to mention the path relative to where you are.
So other way to think of that, I'll give you some time to now try this out.
But the other way to look at this would be, yeah.
Colorful, please go ahead.
Hi, good morning.
You have to be found that already.
Oh, no, no.
Can you change the part?
Sorry, I missed that part.
But you changed the part to it.
Okay.
Makes sense.
Good.
Anybody else?
What you're looking at is very important in the Linux Unix world.
Where something is located.
How do I mention where something is located?
Recommendation is simple.
When in doubt, start from the slash.
Start from the root.
Let's have a look at the whiteboard and understand that better.
So let's say, can you see my whiteboard?
Can I get a quick thumbs up?
All right.
Thank you.
So let's say under the root, we have a folder.
Under the folder home is the folder date.
Under the root is also the folder war.
And under war is a folder log.
If my current working directory is home.
How do I refer to the other locations?
First of all, I can refer to home, which is my current location with a dot.
I'll explain that in a bit.
That's a current location.
If I want to refer to a directory under home, I can just say, for example, CD data.
Where does it assume data is?
It assumes data is under my current location.
That works.
I can also say CD slash home slash data.
That will always work because I'm giving the full absolute path.
How do I change to the log directory?
If I want to give the absolute path and just say, CD slash war slash log.
That works, correct?
Important thing is I started with that.
But if I don't want to give a full path starting from the root, I want to give it relative to where I am.
How do I tell on the file system that from here we need to go up and then go down?
For example, how do I go from home to the root?
Let's try this out.
We're going to do this right now.
We're going to create a simple structure and we will try just maneuvering and moving around.
Can I request everybody to make sure you are in your home directory, please?
Just type CD.
Make sure you're in a home directory slash home slash student.
Any of you know this?
How do I go one step up in the hierarchy?
CD dot dot slash.
So if I do nothing else, CD dot dot simply means go one level up, correct?
Yes.
So I'm here in the home directory slash home.
From here, how do I go one level up?
I should be in the root.
There is no further up to climb.
This is it.
Let's go to our home directory.
From here, how do we go to the var folder, which is under root?
Remember, we are two levels below root, right?
Where will that take us?
From here to here.
So let me first of all just do a quick print working directory to prove that I am in the student folder under home.
What happens if I do this?
What does that mean?
Who's space is that?
Take me to the root, correct?
And then slash var.
Now I'm climbing down the hill.
All the way up to the root.
And now I'm going down into slash var.
Let's have a look.
From slash var, exactly the same way.
How do I go into the home student folder?
Not giving the full absolute path starting from slash.
So what do I start with?
What do I say?
One level up.
That will take me to the root.
And then down.
Can you please try this out on your own?
Make sure you are comfortable navigating around.
Try exactly what we have done.
Please move around a bit.
Once we are comfortable with navigating, then we're going to move into all sorts of commands and working on the system.
But this is the basics.
And you will realize what happens when you do or give spaces.
No spaces in the path.
Keramang as you do CD dot dot.
You know why I said this is not a spectator sport.
When you watch it, everything works.
When you do it, nothing works.
Great.
I can see that works.
Austin, are you back with us?
Is Andrea just checking?
Yes, I'm here.
Give it a try, please.
Exactly what we are trying.
I think I did.
Yeah, I was following.
An old trick.
Let me see if that works.
CD dash.
It just takes you to the last folder you were in.
Just CD dash.
Just takes you wherever you were earlier.
It's a quick way of jumping.
All right.
Could you please come back to your home directory?
Let me also show you the use of dot.
I want to copy.
Something.
Let's say I want to copy some file.
What's missing?
If I just say, hey, I want to copy this file.
It's not happy.
It says one parameter is not enough.
I need two parameters.
You want to copy it.
I just want to say I want to copy it here where I am.
One way of saying where I am is just a single dot.
I hope that's clear.
Dot dot is the directory above.
Dot is the current directory.
So when you do this in your home directory now, there should be a hosts file.
Could you please try the same?
Copy the ETC hosts file into the current.
That should work.
You should have a hosts file in your current home directory.
Please give it a try.
Here dot means current directory.
And take a list wherever you are.
You should have that file.
Brilliant. I can see it works for Austin.
Works for Keramon as well.
Faith, give it a try as well.
Faith says she's coming back.
I can see her working.
Maybe it's the spirit within the body cells.
Works for Faith.
Works for Austin.
Brilliant.
Works for me too.
Don't forget.
What if I was...
Again, this is just a demonstration.
If I want to copy that host file, what happens if I just put that tilde?
What does it do?
That represents...
The home directory.
Yeah, that represents my home directory.
But that would fail because of...
We didn't have a file like that.
Did it say that?
No, no, just take it on your site.
Yeah, yeah.
Do you see it saying that here in my terminal?
No, it didn't.
Linux generally, and Unix in particular, doesn't question you a lot.
You are responsible for your actions.
If you want that friendly option, please try this one.
Minus i.
What's the difference when I do minus i?
Now it cares.
Otherwise, it just does what you ask it to do.
Now it asks the question, hey, do you want to override?
So what happened?
It overrode...
Imagine doing that under the root privileges.
I told you why we call that as the CV updater.
You can wipe a system clean with one wrong command.
Is there a way of falling back?
That's easy.
All that's done is done.
No, what's done is done.
Fall back is update your CV, sir.
Sometimes, and we will see this later on, we will create aliases that make it a little bit easier.
You can try this on the terminal.
And I'm going to talk about this because it's a very important point as well, related to commands.
Do you see some aliases here?
LL is the same as this.
So maybe I can create an alias that says CP is the same as CP minus i.
Now, if I repeat that command, sorry, if I repeat the simple CP command.
Oh, it's doing something helpful.
How long does it keep the alias full?
This is temporary.
It's a temporary environment, unless you put it in some files which make it permanent.
Okay.
It then forgets.
The shell is a programming environment.
You can program it either temporarily or permanent.
Can I recommend all of you to try this out?
Check the current aliases, create a new alias.
And then try the regular CP command.
And see that it is automatically adding the minus i.
Even if you don't do it, the system's doing it for you.
Pay attention to the quotations.
Quotations, spaces, cases, these are all very critical.
Sorry, GP.
Minus i.
Just a question.
Go ahead, please.
Okay.
Just a question.
The up arrow and the C, why does that happen?
That happens to me a lot and I don't always know why or understand why.
Not sure if I follow the question.
Third line from the bottom, right?
With the CP override, home student dose.
And then at the end of it, it's an arrow up and a C.
Why does it do that?
Let me just look at your screen.
No, it's on your screen, actually.
Okay, hang on.
Yeah, at the bottom is third row at the end.
The up arrow and the C.
Ah, that is me interrupting the process.
Control C.
So what happens is when you're reading documentation about Linux online,
you might see a screenshot like this with a Control Z or a Control C.
So Control C is your best friend.
When in doubt, if you're stuck somewhere on a terminal, just press Control C.
It basically interrupts that process if you're stuck somewhere.
Here is an example.
I don't know if it's going to work.
Let's say sleep for 100.
Literally, I'm asking the terminal to go to sleep for 100 seconds.
Okay.
Or I could just do Control C.
To break that process.
100 seconds of sleep, basically.
Lissandra, is it clear?
If you're stuck in a loop or a process is taking very long, then you can...
It's like end task of the windows world.
Okay, I see.
So you get back to your terminal.
I lost you at the beginning when we did...
The alias?
Yes.
Before we got the alias, we were asking to overwrite those.
Yes.
So after that...
That's all right.
Let's just quickly have a look.
So when you...
Go ahead, Austin.
Now, I was asking the command to Jeff, are you then reversing the alias?
No, I'm reversing it.
Is it only going to focus on all of the only aliases or can you specify which one...
I specify the exact one.
So Lissandra, this is what we were trying to do.
We copied some file from the ETC folder into the current location.
Now, if we repeat the command again, it seems to not care.
It is just overwriting the file again and again, which is typical of Linux.
They don't always question you a lot.
If we use command like minus i as an option, it seems that it prevents us from overwriting.
That sounds like a good idea saying, hey, this is going to accidentally overwrite the file.
Would you like to do this? Yes or no?
So maybe we want to replace that every time we type the command CP, it actually executes this one with this option.
For example, I always like to do LSLTR.
This is my favorite way of taking a list.
If I just type the command list, it says, well, there is no such thing.
What I can do is I can make an alias where I can say list equals to LS minus LTR.
I'm just making a shortcut for a command.
Keep in mind, as I mentioned to Austin right now, this is just temporary on this level.
Now, if I type the command list, it should execute that alias.
And I can also double check the aliases currently on that system.
You can try this out, please.
And that should work.
I'm sorry, I just want to see the alias list command that you used.
You think command just try exactly the same thing, Austin?
Just type an alias and the alias you created.
An alias and the alias you created was list, right?
No, I mean that list, yes.
Then you just say CP, right? An alias CP.
That's the one you created.
So CP will be replaced with the CP minus I.
Alias is just make your life a little bit easier.
So Karamang, you're experiencing something on the shelf.
You started a quotation, but he did not close the quotation.
When you press the enter, you started seeing weird new lines coming up.
And you said, let me get out of here with a control C.
Which is fine.
So that's a perfect example of when to use control C.
You might have to unalias it.
I think that alias never got created, right?
Because you did control C.
Yes, but then I just typed it.
You tried it again, alias.
Ah, too many spaces, Karamang.
You love spaces, get rid of the spaces.
After list.
That's why you have to look a bit more carefully.
It's just pretty small.
I meant in general.
There is a space after list as well that you want to get rid of.
Now you know.
Watching it is the easiest thing to do.
There is a T missing before you press enter.
Missing windows already.
I'm just out of curiosity.
Yes.
You can just mention the path of anything.
So that will kick off that particular script.
It doesn't matter what you're executing.
Are we all good?
So that's alias can be handy.
However, this ties into a very important concept, which is.
When we are executing commands, where are they actually located as executables?
Let's have a quick look at that.
Give me a quick second.
Hello.
Yes.
After.
From.
Sir, bye bye.
I'm in a meeting.
Thank you.
So there is an interesting command called as which.
And what it shows is that the command Alice that you're executing on the file
system, where is it found?
And turns out it is found in the bin or the binary folder.
What if I look at tools which are meant for let's say.
The administrator.
System administration tool.
This system administration tool is in another location called as S bin.
Basically, this tool.
Sits in a folder which contains like management tools or administrative tools.
Now, why does it matter where something is located?
Well, one is that it gives you an indication that this is not an average system shell.
But this is mostly a command for the administrator to manage the system.
Also, sometimes if there is an alias, you can ignore it by directly executing the command from where it is.
Let me show you what do I mean.
I'm going to show two quick demonstrations here to get.
The first thing that I'm going to do.
Is I'll just keep two terminals just side by side.
In the first terminal.
First up.
Let me look at the aliases.
Let me create an alias.
CP equals to.
CP minus I.
And I can prove this that.
Now, if I copy.
Something into my current directory, you can see that it is asking, hey, do you want to override?
So clearly the replacement of the command has worked.
But what's this?
I want to know where this command actually is and directly run it like this.
I mentioned the full location of.
What happens when I directly run the command from a location?
Let's see.
Does it care about the alias anymore?
No, it doesn't.
But if I run the command CP again.
The alias is working.
What have we learned?
If you want to be 100% sure.
That you're not using any shortcuts or aliases, you can always mention the full location of the application that you're executing.
Because sometimes these aliases can be annoying, but we want to temporarily avoid them.
Does that make sense?
This is temporarily avoiding the alias.
If I just run CP, it will be replaced.
But if I want to run CP without this alias.
Austin, I don't have to unalias it.
I can keep the alias just temporarily run.
But how do I know where does the binary exist?
So guess what?
All you have to do is this command.
Can you try this out, please?
Just to ask, just one thing.
So most of the commands that you normally use, like your list, copy and all of those, they are all sitting underneath that path.
In bin, in binary directory.
That's correct.
In bin.
Under USR.
And the administrative tools are in SBIN.
Please give it a try.
I'll be back in just a minute.
And back to you all.
Let me check out how things are.
So very nice command.
Which, where is this command located?
In which folder is the command located?
And quick short summary.
Typical system tools are in the user bin directory.
And administrative tools are in the user SBIN.
And again, at any point in time, if something is not clear, please ask.
We explore a little bit more of the fundamentals and move into the other aspects of managing or working with the command line.
OK, I can see this is working for most of us.
All right, back to my terminal.
A few other quick basics on working on the system itself.
Maybe we have seen already how to identify some basic parameters.
Maybe one of the other things we want to know is who are we?
And there is a very nice command.
Who am I?
And it says you are student.
If I write the command ID, it tells me a little bit more about my user.
What is the ID of my user?
And what is my main group and other groups that I am part of?
So it gives a little bit more details about the current user account that I am in.
Very handy command.
I can't wait until you show us if you are root, if somebody is suited as root, right?
And yes, can you if you are suited as root, can I still write the command that will show me my home?
Home account.
If I am suited as root, can I remember what my original username is?
I am looking forward to learning about that command.
Sure, let's just take it out right now.
So right now, who am I says I am student, correct?
And my ID shows 1000 as my current ID.
And if I try to run some tool to manage the hard disk, it says OK.
That's the tool.
And if I try to actually work on the disk.
Let's try something.
I'm going to switch using the sudo tool.
I'm going to run the shell and that shell will have the privileges of the root user.
Now, if you do sudo bash, I think we can notice first up that in the profile, the way the prompt shows on the terminal gives me an indication.
Also, it tells me I am root at the rate, the name of that system.
That's another indicator.
What if I say, who am I?
It says, well, right now, you are root.
If I type the command ID, it says you are root.
The question that you had was like, who I really am.
Try this one.
This is like literally shouting at the system.
Who am I?
And it is fine.
You are student.
Give that a try.
Linux is fun, isn't it?
So you must shout if you want it.
Yeah, please don't tell to others.
What did you learn in the class today?
You have to really shout at the system and then it will give you the real information.
Yes.
I mean, that's one way of remembering it.
You literally have to shout at this.
Hopefully that answers the question.
Yes, it does.
Yes, it does.
Can it be used in scripts?
Anything and everything can be run in script.
Script is just a shell environment which is programmed to execute.
Anything and everything can be in a script.
And I'm happy if we can continue.
Many things you can do in the system.
Linux is still programmable.
So hopefully this tells us again who we are and what we are executing the command as.
We know a little bit about now the options, the idea of commands and options and printing our identity.
Let's try a few other simple commands just working on Linux as well.
Just familiarizing ourselves, so to speak.
Since we are still working on the file system, let's just also have a look at just the idea of creating links.
I think this might be a bit handy.
Let's have a look at that.
Then we look at the file system like copy and move and all of that.
We can quickly try this out since we are already onto the file system and a little bit comfortable working with the commands themselves.
So some basics.
Let me switch back to where I was.
So I have a file here.
First of all, I can just make sure that I am exiting out of root.
Just making sure I'm back as a normal user.
I'm happily sitting in my home directory.
I can execute as we saw different commands and I can create some files.
So for instance, if I have a quick look at this file.
And I think we currently have a host file already in our home directory.
So I already have a file in my home directory.
So what I can do here is I can create what we consider as links and we can create links.
We have to be careful when we use the word link because it's not exactly how we imagine it works in the Windows world.
Let's give that a try.
I'm going to use the command LN and LN says make links between files.
Careful, folders are also links.
So when it says files, don't just think of stroke.
Couple of options.
I'm going to try them out and here is an option that says minus S symbolic links.
Let me explain.
So I'm saying there is a file hosts already and I would like to create a link to it.
I will just put a little asterisk so any and everything that starts from hosts will show up.
I can also put it in.
It may not be very happy with that, but that works.
So if you just do what I have done right now, which is make a link from hosts to new hosts.
And you can kind of see that here.
It actually says this one points to that one.
If I read this file, cat or more or any of these tools will work.
If I read this, it displays the content.
So that means we can say that or we can argue that the shortcut is working.
When I work on this, it reads from there.
Just a quick question as you try this.
What happens if I delete the original file?
The link will still be there, but there will be no source.
So it wouldn't work, isn't it?
Yeah, it wouldn't work.
I'll just wait for you guys to try this part out first.
Make sure you are a student, not as root, not as root.
Call a fellow.
Thank you.
Are you awesome?
She wants to be fired.
Hey, it's not a fire. Maybe, you know, just looking for a promotion.
We do need to scare people away from root.
So I believe the shortcut kind of works, right?
It just works.
And faith, I did the star host star because any anything it starts with.
And in the middle is hosts.
So that will give you both the files.
So you made a mistake with the source host faith.
You mentioned the source as host, not hosts.
It still followed your order. It said, yes, sir.
But the trouble is the original file doesn't exist.
The terminal is very kind to you, showing in red.
I wish things were like this 30 years ago.
Green and red, but doesn't exist.
You can repeat the command again or just pick another file.
Yeah, so if you try faith, you're going to get an error.
Try to read that file.
It's fine, which is the perfect example of what we want to show.
So here.
I have the host file.
The new host file, which is a link.
Starts with an L.
What happens if I remove the host?
It's not very happy.
Of course, if I try to read it, it doesn't work.
So there is another concept.
Which we call as hard links.
Let me explain what is the hard link.
Suddenly you won't have to read too much about it.
The idea of the hard link is something like think of the file as a room.
So let's take a room and.
All right, let's take a room and paint it blue.
Now, if I create two doors in this room, does it matter which door do I enter from?
What color am I going to?
Doesn't matter, right?
I enter the same room, isn't it?
It just has two doors.
This idea is called as hard link.
If I close one door, do I have another?
What if I create many doors?
How many doors I need working to access the room?
Minimum one.
As long as there is one door you are in, isn't it?
This is the idea of what we call as a hard link.
Let me show you.
OK, I'm going to copy the original.
Host file.
And to the current directory.
I'm going to make a link, but this time I will not use the option minuses.
I will just say host host one.
Do you notice there is a number here which is incrementing?
Now it is two.
What do you guess that number two is?
Think of my analogy I just gave you right now.
Two doors?
Absolutely, these are two doors.
What if I keep saying, Ellen, host one to host two?
Look at the original file.
Three.
If I get rid of that first file, that's OK.
We still have two more doors.
And it will still work.
Can you please try this out?
This is called as hard links.
You can do that in Windows as well.
Just to show you the concept.
Please give it a try.
CPE slash host.
You got it right.
It's important that we try things out.
So if you make mistakes, we learn from it.
It's under ls minus l host star.
So you see all the files where the name begins with hosts.
I'm not sure if I was supposed to press enter because I did.
And then all of these came up.
After cat there is one.
Right.
Just looking at what you.
Yeah, yeah.
So this is the content of that file.
Yeah.
So cat is just a command to read a text file.
So one command that generally comes in very handy.
We will have this here as well.
Is this.
Just this file.
If you want to know what type of file something is.
Have you noticed in Linux we don't really have extensions.
In Linux there is nothing called as file extension.
So I can literally create a file like this.
The only trouble with that is.
If there is a file, we don't know what is in it.
Here is an example.
What type of file is this.
This is an executable.
What type of file is ETC host.
That's a text file.
What type of file is my file is so cool it's empty.
So the file command is very handy in knowing what is the file.
What type of file it is.
Is it a PDF?
Is it an image?
Is it text?
Since extensions are not really a thing.
I like that people are creating the file exactly as I said.
My file is so cool.
Appreciate that.
Okay.
That's fine.
Can we create it with our own.
Yeah.
No need for extension.
There is nothing called as extension.
So if you are looking at something and you don't know what it is.
Use the file command.
Of course, please use the tab to autocomplete.
If you are writing the path.
If you are writing a command.
Just use the tab.
It will autocomplete.
And it reduces the number of errors.
Just under file and extensions there, right?
So if you want to create a file for PDF as an example.
How would you go about creating that since you are not including the extensions?
Because most of the time I've noticed that.
For me I always just take a shortcut.
I just find a file with the same format and then just copy it to use it.
But I've never actually created a file with a different file extension there.
Yeah.
So the only thing we can create is just an empty file or a text file.
Other files you will create using applications.
Nothing different there.
But these are the basic things that can make it very confusing when you work on Linux operating system.
It looks very different than the OS windows that you are comfortable with.
Yeah, that's true.
Extensions are a very big thing on Windows.
So now if you don't have them, yeah.
Sometimes you will have them.
Sometimes you may not.
So that's cool.
All right.
So that was a little bit about the links and a little bit about just navigation generally speaking.
Let's just work on the command line a little bit more so that we can do like copy paste, just move things around a bit.
Manipulate the contents a bit beyond what we have just seen right now.
So we'll just have a quick look at the copy, the rename and other things so that we feel comfortable with that process.
All right. Back to my terminal.
So we are comfortable moving around.
Again, I'm making sure I'm a student.
I'm in my current directory.
First, let me very quickly handle renaming and moving because the command is same.
What does that mean?
Let me create a file.
Data one.
If I say move data one to data two.
MV is not moving it because there is nothing called as data two right now.
So MV says, OK, in that case, you want me to rename it.
I'll rename it.
If I say MV data two to data three.
It does the same thing.
It says there is nothing called as data three here.
So most likely you want me to rename it.
I will rename it.
Wait a second.
What if I create a folder called as data five or data four?
And I say, let's MV data three to data four.
Something is different now.
The command is the same.
But what is different is what I have mentioned as a destination actually exists as a folder.
In Linux, a file or a folder cannot have the same name in the same location.
So if I do this, what it has done is it has taken this.
That is my data four.
You can see that that folder now contains this file.
So it's the same command is for renaming and the same command is for a move as well.
The key here is, does the destination already exist?
If it doesn't, it just doesn't.
If it doesn't, then it's a move.
Because the fundamental idea is that you cannot have a file or a folder which has the same name.
Here is an example.
I'm going to create a file.
I'm sorry.
So you say you moved that file into the folder.
But if you already had a file or had a folder with the same name, what would have happened?
For example, if you are moving the data three right into into data four and I need a data four folder.
You already have a folder named data three.
Same as before.
It won't it won't bother unless you do the minus i.
It just won't bother.
It will override happily.
So minus i is your friend with these commands.
Okay.
Careful with that one.
Okay.
So let's say I create a file called as July.
This is a file.
I can verify that, right?
There is a dash here.
It's a file.
What if I want to create a folder called as July?
Should it allow you to do this or not?
No, it shouldn't.
So there's the same thing.
Because a folder is also a file.
In the Linux, everything is fine.
So you get a very confusing message, right?
Cannot create a directory because the file exists.
And then you'll be listing and not seeing it.
And you're like, where is this file July?
I don't see it.
There's no other folder called as July.
It's just that we cannot have the same name because the system treats them as the same.
Just something for you to notice.
So that's MV can be used for rename.
Can be used for a move.
You can also obviously use commands like CP.
Call a fellow.
Please go ahead.
Before we move on.
So what if I touch July dot extension?
Like maybe CSV and I make a folder called July.
Will it still be the same?
Yeah.
So the idea here is good that you mentioned it.
If a folder already exists.
Let's take an example.
This is my current home directory.
I see there is a folder called as the.
Or data for.
And I have a file here as well.
Right.
So let's take an example.
You can see this.
I'm going to start scratch.
I will just do something very quickly.
I will get the host file in the current folder.
And this minus this host file works all as well.
What would happen if I touch this file right now?
The file already exists and it has some content.
Any guess?
Overwrite this file.
Not really.
It will only update the date and time stamp.
That is a non destructive command.
What happens if I touch a folder that exists?
Same thing.
It is only going to update the timestamp.
If you create a file first.
It won't let you create a folder with the same name.
Because another file exists.
Does that answer your question?
I think.
Let me try it out.
Try exactly what you see.
Same for the others.
Feel free to try.
And I appreciate the questions coming in.
Okay.
I know you can't see me.
But I'm shaking my head vigorously.
Linux is fun.
It takes a while for you to warm up to it.
But it's all right.
Let's try a little bit more just on the file system.
Similarly, let's just have a super quick look.
And how you will copy things.
We have already seen CP.
But as we work on CP again.
I'm making sure I'm in the current location.
By the way, you can make an entire directory structure with a minus P.
For example, in the current folder.
I want backup.
Slash.
Files slash January.
So what it does.
Is this just creates the whole path for me.
I don't have to do it step by step.
It's kind of nice.
When I'm doing a copy, of course, I can use the wild cards.
Can be useful.
For example, I can say, let's copy from ETC.
Anything that ends with the dot com.
So multiple files might match this filter.
Where do I want them to go?
I want them to go into my backup files.
Jen folder.
Just a quick copy.
What if I want to copy a whole folder?
It says I don't like copying folders till you mention minus R.
Fine.
We will mention minus R.
Recursive.
I have two folders.
So that's a simple example of copying files and folders.
Please try both.
Can you please go up a bit?
Let's see if.
I didn't miss anything.
Yeah, there was one folder path that we created.
Yeah, which is that.
That's one.
Good works for this Andre.
Call a fellow.
I appreciate you guys doing everything with me live.
Yeah, Mohammed trained as well.
He'll be back with you.
Don't worry.
Just we're not complaining.
We're not complaining.
That as well.
If you see any errors, just revisit and one more suggestion.
Use the tab to auto complete, especially if there is a path file names backup files.
Is there a folder like that?
Yeah, should be Jen.
And then later on, you're copying that folder to another.
I'm just one thing.
What would cause a delay?
When you're in the training room, I'm struggling to see your screen anymore.
I think we still see connecting and connecting, but it's not showing up.
Is anyone still in the training room?
That's true.
That might be a network issue, right?
I'm just trying to refresh.
Yeah, I did that.
I just want to do something.
They can fall.
I mean, we should think to a different browser sometime.
Could just do the trick as well.
Okay, I just need a second.
I can see it works for everybody else.
Yep.
Wait, so minus R is forcing it to do it for a folder as well or a directory.
Yeah.
Austin, let me know if it works.
Yeah, let's switch sometimes.
All right, let's copy and move a little bit.
Some other file system level tricks.
What if you want to get rid of things?
So we have the command RM.
Thankfully, it does not assume anything.
It says if you want to remove, well, what do you want to remove?
Maybe I want to remove a file.
No questions asked.
Maybe I want to remove all the files that begin with hosts.
No questions asked.
What if I want to get rid of the folder?
Doesn't like it.
Hey, it's a directory.
Okay.
How about now?
Well, that is fine.
If you insist.
We'll get rid of that.
Give it a good go.
And it can't remove what you don't have.
So I can just do LS minus L to see what files you have.
You can remove something that exists that you created.
I have data three file one file two.
Good for most of you.
Right.
That's frankly more on the file system.
And then obviously there are lots of tips and tricks in terms of reading the files.
We're going to try those out as well.
There are some other just I would say shell related tricks.
Simple things that you probably can try out.
If you remember that was the command date.
This was the who am I.
What happens if I do this?
Wait.
And who am I?
Executes multiple commands at once.
Nice to get many things done at the same time.
We can execute multiple commands.
And there are other interesting ways to kind of chain the commands together.
Do the second one only if the first one works or do the second one only if the second one or the first one doesn't work.
There are many ways to chain these together.
But that's the easiest of all just in terms of executing kind of commands together.
And I may have executed many commands earlier.
I can have a look at the history.
And it's a long history.
And maybe I can repeat some command from the history.
Let's say my command number 174.
That I copied a file.
So I check the history.
Just do that.
I write the command history.
Figure out a command I would like to repeat.
I can just do exclamation mark and put that command number.
Saves time.
Nice one.
But first please check your history before you execute.
Type the command history first.
I can't hear anything.
You guys are getting nothing when you do history?
I'm saying I can't hear you.
So I don't know what I'm doing at all.
What I need to do.
Wait, can you not hear me?
Oh, is that history? No, we couldn't hear you.
Okay, now we are back.
I said write the command history first.
To get the list of all the commands.
And I picked one of the commands where I was copying a file.
So I executed that command again.
Just by writing exclamation mark.
Don't do that.
Because it's your history that you need to follow.
I think she wrote line 144444.
That's a very long training course.
Just have a look at my output.
I just did a bit of history.
Any command.
Let's say there is a command that says who am I.
199.
I can just repeat any command with an exclamation mark and the command number.
Pick a command of your choice from your history.
So that's kind of handy.
And again, just repeating anything that you might have done before.
And saves us time.
So there's a bit on the file system.
It's also a little bit also on just working with the history itself.
And then comes in working with the text command and so on and so forth.
What's a good time for your lunch break?
Typically, is it now?
I'm happy to have a lunch break.
We're squeezing just another 30 minutes of this time.
That's about 27 minutes.
You want to carry on for another half an hour?
Half an hour is too long.
25 minutes.
Oh, wow.
That's such a big difference between 25 minutes and half an hour.
I'm learning things about South Africa.
I thought I didn't know.
Five minutes is a lot.
Five minutes is a lot.
Yeah, yeah.
It's a mind thing.
Don't tell us 30 minutes.
Five minutes.
Yeah, that is very true.
And I have clients that I work with and there are amazing people sometimes I work with.
There is a meeting invite that they send you.
They send me like a meeting invite.
Three weeks from now.
And between now and then I'll receive at least 10 changes of the schedule time.
Up until like a day before it.
I'm not entirely sure what the purpose of sending the invite out was.
It's just to make sure all the resources invited have that exact opening.
Yeah, you can't say I didn't know.
That's it.
Yeah, we told you a month ago we're going to meet sometime.
That's it.
That's good enough.
Work with it.
That's fine.
Happy to carry on.
So that was a little bit on just in terms of tips and tricks on the show.
We're going to see a bit.
Hopefully we are comfortable with the navigation of the file system itself.
And frankly, every single command has many options that you can explore.
And that's part of as you work with the system.
We learned based on what we need.
So we don't open the main page and read the 10 million options.
We go based on the task at hand.
If needed, then we look into the options and we learn more about the options.
So this is more about just familiarizing the file system with the shell, the way to move around and so on and so forth.
OK, a few more.
Go ahead, please.
What is the command that you screened at the machine there?
Because the way I'm typing is not going through.
Are you writing it?
No, not that one. The shouting one.
The who, M, I?
Who, space, M, space, I.
That's it. Don't type that.
Let me check. OK, thanks.
The one we equated as shouting at the system.
Wouldn't do much if you're already signed in and that you're not going to see anything.
Oh, it didn't show anything.
That's why I was asking.
They say what is this would make it like that?
When you are switched to another user using Sulu and other tools, then it will show you the original user ID.
OK.
OK, now look at that.
All right.
Working with, as we are currently on the file system, just a quick look at how do you work with text files.
First quick reminder.
The command file can tell you that you are working with what type of file in this case, a text file.
We have many commands.
So let's check out, for example, this file.
ETC password, which contains everything except passwords.
If I want to look at that file.
I can get it.
Basically, it reads the text file and shows it to me.
But if it's the long file, it just kind of runs through the screen.
Instead of cat, which is good for small output, I can use the command more.
Which allows me to read the file kind of step by step.
I can press enter or space.
Here I'm pressing enter.
Line by line or press space page by page.
And this is just an example of reading a text file.
So we have cat for things that fit in a page.
If it's a Musbiger file, you can use the command more.
If you want to read the.
Let me try this out.
If you want to start reading from the bottom up, you can sort it out.
We have cat, we have tack.
This is literally the opposite.
So here tack reads from the bottom.
Cat reads from the top.
Each has its own advantages, what you want to read.
Sometimes, for example, if I say cat slash hosts.
Or if I say tack slash etc slash hosts.
I start from what was the last entry.
Maybe that's what I want to see.
In many Linux configuration files, we make changes by editing the file and making some entry into it.
So for instance.
Let's take an example.
You can try all of these commands, cat, tack, more.
One of the very useful commands is the one that counts how many lines are in a file.
Here is WC word count.
If I just press enter and I write some.
For example, this is sentence one.
This is second one.
There are 12 words.
And if I do like control C or control D here, end of file.
Control D is end of file.
You don't see the control D that I am doing.
What word count is doing is taking the text and saying there is one line.
Four words.
18 characters.
So what if I do word count for an existing file?
Let's say etc hosts.
Hosts.
I just want to see how many lines.
And it says there are 14 lines in that file.
In Linux, many commands on their own don't make a lot of sense.
Like why would you care about this till a day you care about?
There is some use and you're like, oh, I wish I could count the number of lines.
For example, how many users in this system?
Well, I know that this file has one line for every user.
So this tells me that there are 50 users defined in the operating system.
So counting can be very handy.
If I want to read the file, I can use the command more or the cat to read.
Remember, this is for text files, not PDFs, not executables.
We are looking at text only.
You can try this out.
It doesn't work on executable.
The word count, because this is for executables.
So executables like binary files, this won't work.
You will see each image.
Your terminal will kind of freeze.
Happy to show you that.
Let's try to get the second session.
And then.
Sorry, could you could you say it again?
No, I didn't want it to freeze.
I tried on the PDF.
Yeah, it won't work on binary files very well.
It's for ASCII text.
Faith, after you write a couple of lines, press control D.
Control D is the character for end of file.
OK, thank you.
That's OK.
Back in a quick second.
Just underneath yellow, how are you?
Those numbers, what are those for?
Because I know it reads how many characters are there.
But the 1 and the 4, what are you going to do?
Say it again, please.
On the WC, right?
In the last sentence.
Again, you do the control D to count the number of characters.
And the total weight is 80.
So what does the 1 and the 4 actually represent?
Because that's where I'm lost now.
Oh, the WC dash L.
Or the 1.
I don't know.
The 1 and the 4.
That's what I want to understand.
I think it's one line.
It's one line, four words, 18 characters.
Oh, four words.
OK.
So if you do it again and maybe have multiple lines, it might return.
Because I didn't do a different thing.
You gave me five.
One, two, three, four, five.
Oh, yeah, I should write.
I didn't completely do the other sentences.
I did.
OK, thanks.
I don't know.
OK.
So I WC then wrote two lines.
And control D, I get.
It seems to only count at the last line.
Let's see.
Let's see.
Color.
Yes.
No, what do you say you counted?
So I run around the command and I wrote two lines of what?
Not two lines.
And then the count only return the last line.
Is it?
All right, so back with you guys
Yes, press enter press enter go to a third line and then do the control D
What is the definition of a line
Anything after and anything at the end there is a carriage return CR IBM terminology
We need a carriage return. We need an enter for it to be registered as a line. So guess back in the Unix days
Administrators will edit a configuration file
Type a new line at the end of it save it and the system later on will generate an error
And you will read the file through the cat command and you're like what is incomplete about it
What it won't tell you in simple English is a man just go present Austin now try control D
So I mean it's improved quite a bit in the new generation of operating systems
but back in the day this enter was
Let's put it this way. There were 10 million ways of me. So that's why Austin, you know Unix
Administrators will look down upon the Windows administrators saying you guys are just clicky clacky. You don't know anything
So I'm just also suffering
Unless you know the true hierarchy of how the kernel works. You're not a true admin. Yeah, that's look
There is some truth to it, but then it's about being productive
Hopefully that answers the question if there was a question in the first place
Yes, even this the shift and I also get recognized
Right, so that's a little bit of cat and more and word count and all of that
Just from the file system and working from or working with
Text now why we care so much about working with text. It's because a lot of not a lot pretty much
the system
Configuration is spread across in text files
So in back in the day you would have to know every text file where it is and for what purpose
What changes have to be made into it today? You use graphical tools to do administration, but behind the scene
Many of them will go and update the actual files
hence the
You need to know how to work with text file was an important bit
Still to some extent still very true
So for instance
Let's have a look at this file
And this file simply has a mapping for your own network engineers
So I have the IP address and a hostname
And if I do let's say
Let's try
The current hostname
Let's look at the existing host file
That works and if I ping DD node
That hostname works as well
If I want to add another local hostname entry for that, I'll have to edit that file
So working on text files kind of an important aspect at least from the configuration
perspective for instance
These days you're gonna find
Graphical editors, so let's choose like nano
It is a player again
Is it the audio or the interface? No, it was only the audio the interface is still there, but I can hear you again
Okay
So
I hope you can still hear me
Let me know if I am audible a quick thumbs up would work. Yes
Yeah
I'm just a clip one. Yeah, just you access the GNU there
The graphical editor, yeah, yeah, I'll just show it again. I'll just show it again
So, let's say I create just an empty file
file X I
Can use a graphical editor like nano, let's say I mention nano file X. I
Type a few things in this
And again for others that character means control
So control X is exit
Control K
All of these are shortcuts here is a control X do you want to save
Yes
What's the file name file X and let me read that file?
Okay, there's gibberish in there, but can you just do exactly what I did?
Just create a blank file use the editor nano to open that file
Type something in use control X to exit save
Once you are back just verify that the file contains that content
The nano is a friendly tool. There are many such friendly text editors. I
Have to be honest. I am not used to the friendly text editors. All I know is the super old-school
I am also not very familiar with
Friendly, yeah, yeah. I am I feel uncomfortable in friendly editors. I'm much more comfortable with me
But it's a matter of what do you start?
Can you do like a line come to it man on
There's a lot you can do with VI as well
That colon set and you
Million things you can do with it again
We I the only reason someone like me would prefer me I because that kind of works in every distribution that I work on
So when I used to work on solaris it worked their HPU exit work there
Every flavor every distribution of everything. I know that that classic tool just works
Control
I
Have saved buffer as an option as well as you're working an existing file you can just say I want to say
Or actually I don't know what I did that time but you didn't give me that option anyway
Yeah, yeah, I don't know what I did that time but it's fine. All right that works for you. How about the other?
Please give nano a quick try if you're already used to it and you use it on a daily basis, then it's fine
But showing you that there are text editors
Nonetheless and depending on the distribution that you're on you might find some tool
You have no no you have G edit there are many tools
Again they all range in the level of
Friendliness and then the commands that they support
Just pick the one that works for you if you don't want to deal with a million command something like nano and G edit
I can give you I can give an example if I work on I don't know if you can see my screen if I work on
I
Was I have to type I to insert something right? Yeah
Let's say I accidentally said today is 91st, but what I wanted to say was today is 19th
Here I can
Work
Go here escape XP I can just quickly transpose if I need to
How many people need to switch the two characters I
Want to make this 32
Yeah, I can I have many tricks in vi
Oh
But then well not everybody needs those tricks
So
Let's come on so please pick a text editor that
But you can install some of these but because
Nano is already there that kind of fits the bill
So various different text editors which can come in
Is this the time for lunch or we are on the 26th or 27th minute
I
Can see you guys enjoy meetings quite a bit
Question
All right, so we take a break now I think by now we have a
Fundamental level of comfort just working around in system. We come back
We look at more commands other things on the command line that make our life a little bit easier
Will be coming back in typically is it 45 minutes
All right, nobody's saying anything so it's 45 minutes
Oh
Fair enough are you taking advantage of the fact that I don't know
We do that with us
It's in the SLA is it okay
All right, it's part of our KPI is it all goes on
I get it. I get it. I
Live it I live and breathe in the same space that you guys do
I'll probably sign in again later. Yep makes sense
I
Oh my god! Who put this here?
They put it here to see the curtains.
This is the food and the other one is the lift.
This one is for drinking alcohol.
The delivery has started.
Follow up press 2.
The delivery has started.
How did it come so fast?
It was their field trip today.
But now they come by themselves.
That's why it takes so long.
Did you go to the washroom?
Yes.
Let's go.
Oh my god!
Oh my God, what a cold girl!
Surprise!
My...
There were only four children in the bus.
Really?
For the children.
What do you mean?
Like, there were only four children.
Were there four children in the free trip?
No, there were four children in the bus.
Okay, to take you guys there.
Yeah, that's right.
Can you please wash your face?
I need water!
Good job.
So, after we came back from the free trip,
it was practically free for the whole day.
She was not to make a study and she was outside and she didn't care.
Like, me, Ethan and Parneka were playing ball in the corridor.
She didn't go in the corridor because in the fourth day, I think some teachers had a meeting.
So we weren't allowed to go there.
No.
I don't want to go to the park.
Will you come?
Can I take a picture?
Yeah, put up when I just come.
She also needs to know.
But you won't come first, you'll eat and then you'll go.
So, me, Parneka, Ethan and Parneka were playing in the corridor.
So, Parneka threw it and it hit Ethan's head.
It went like this.
It hit here.
It was so high that it bounced off.
And it hit Royce, the sixth grade footballer.
It hit his ear.
And we were like, who did that?
And he went down to pick up the ball and his trousers split.
It was so hilarious.
Then his trousers split.
Then we ran.
We went to the staff room and we couldn't stop laughing and laughing.
And then when we came back to class, I was like, why are you in the sixth grade class?
I was like, why are you laughing so much?
I was like, why are you...
Till you wash and come, I'm not discussing anything.
So, I have to do my night right now.
I promise I can go to the park before eating.
Before eating?
Yes, early in the morning.
You didn't eat anything?
Did you take something with you?
Yes.
What did you take with you?
I didn't take anything with me.
And I also...
You finished everything?
I finished all the stuff.
Okay.
Do one thing.
Wash your hands.
And I'm fine.
Wash your hands.
Take your aunt with you.
Play.
Come and take a bath.
Okay.
I'll have tea.
First, check if your aunt is free.
Yes, until then, eat your aunt's food and then take her.
You can go change your clothes off.
Yes, listen.
Let your aunt eat first.
You go after 10 minutes. Let's have a food.
You go after 10 minutes.
You go after 10 minutes. Let's have a food.
You go after 10 minutes.
You go after 10 minutes. Let's have a food.
You go after 10 minutes. Let's have a food.
You go after 10 minutes. Let's have a food.
An ethernet port, a quarantine input, an optical audio out for connecting a sound bar, and two USB ports.
The included fiber optic cable is only 5 meters long and isn't rated for in-wall use.
For in-wall installation, Samsung sells a longer and in-wall rated cable.
Next we have the Slim Fit Wall Mount.
Mounting it isn't the most exciting part, but Samsung makes it easy.
First, attach the bracket to the back of the TV with the provided screws.
There are two lengths.
Longer screw for the use with the spacers if your wall isn't flush, and the shorter screws for flush walls.
The bracket might seem loose, but that's intentional for flexibility.
Mount the wall bracket using the provided template.
Connect T1 and T2 based on your TV sizes.
Tape it to the wall and mark the start point.
Use a start finder if necessary.
Drill pilot holes, ensuring they are level, and attach the wall bracket with the provided screws.
In my case, I used a magnetic laser level to make sure that the bracket was leveled.
The end-to-end bracket length for a 65-inch TV is 42 inches, which you can confirm from using the template or by measuring the TV bracket.
I also installed a 14-inch structured media enclosure from Leviton behind the TV to house the One Connect box, with power and two ethernet cables for a wired connection.
I prefer admiring my devices whenever possible.
Before mounting, I placed the One Connect box in the recessed enclosure, connected all the wires, and installed my Apple TV box.
I also ran an HDMI cable through a PVC flex for easy future connections without removing the TV.
Then, we mounted the TV.
The bracket works like a picture frame.
Without these two people, lift the TV, align the wall and the TV bracket, connect the power cable, and place the hook into the wall bracket.
There's a magnetic piece between the wall bracket and the TV that ensures that the TV sits flush against the wall.
Okay, coming.
I can't do it here.
So you sit on it.
Oh, these are the people falling over.
Oh, that's perfect.
I tried before.
Go around and sit on that.
Oh dear, oh dear, oh dear.
You sit on it, and then you go...
Oh, no, no, no, no, no.
I don't know.
You don't have to be so comfortable.
You don't have to be ready for something like that.
So you're there, and that's it.
You're just waiting for it to work.
Yeah.
All right.
Sir? Hello?
Sir?
Okay.
What's up?
Brand new tiles, son.
I have some sense of responsibility towards your house, brother.
The general recommendation for TV-mounted eyes is at the center of the screen at eye level.
There are only seven children in our class.
The other parents come because the trip was excuse.
Like the last time they already went for a day one,
but that day I came two hours later and I'm over it.
Mmm.
Okay.
Okay.
It's not always a term used in the right sense.
It could be considered as rude.
It's just like a girl who's a little bit more boyish in behavior.
Yeah, because if my friend told me that I was a tomboy,
I would like to take football and basketball and keep on getting hurt.
That's it.
And that is rare.
We need to learn how to just ignore...
I didn't think it was mean.
That's okay.
I'll just think of it.
There, there, there.
There we go.
That's it.
That's it.
In the morning.
11 o'clock on television.
What kind of video?
Because I want to see,
No, I don't wanna No, I don't wanna
What have I told you about touching anybody's screen now?
He was trying to get out of there on the top.
And he is calling others.
Oh, oh, oh, okay.
Okay.
It was so disappointed when it came down and there was nothing there.
Why is it disappointed or disappointed?
It would be like disappointed.
It would be like this. Look. See like this.
And then you see the second one join the first one. One and two.
Look at that.
One, two, three, four.
And then it was a reflection.
This one was hitting him.
It's the funniest thing I ever saw. They were sitting together.
This one took off.
And he pulled him from behind and went down.
This is a video from Sanjana.
Try going up and down. The door is open.
Look down a little bit.
But it didn't come down.
Both of them kept trying to go from the top.
But it could have been smarter than us, to be honest.
It could have been smarter.
He was sitting on top.
Did you get water?
You're not coming down. Look at both of them.
I wonder how we get out.
Well...
30 centimeters down.
The door is completely open.
They're sitting inside for 3 minutes.
How do we get out?
What do we do? How do we get out?
You're done.
The meeting is over.
You have to charge your phone and then go out on your own.
That's not happening.
Will you go with your auntie?
You can charge your phone and then go.
I'll tell you a funny thing that happened in my school.
Surya went to the real park.
Huh?
Bye bye.
Bye bye.
Bye bye.
Bye bye.
Bye bye.
Bye bye.
Bye bye.
Bye bye.
Lovely. Thanks for letting me in.
Welcome back.
Hello.
Welcome back.
Welcome back.
Welcome.
Welcome.
You're the one who's letting us in.
Yes.
I think the whole people are late.
That thing was come to me.
I don't see KG.
I think maybe she'll be joining in a while.
Just give a few minutes for others to be here.
I recorded, but need to drop for a while.
I recorded, but need to drop for a while.
Yes.
So now we are left with Faith and Austin.
Faith, you're around?
Yes, I'm here.
Is everyone here from Cape Town?
Joburg, where are you from?
I'm from Cape Town.
Lisada as well.
Coffee time, Faith. Coffee time.
She just came from lunch.
She's busy with some work.
I didn't get a chance to go on lunch.
Lunch breaks are for meetings without eating.
Lunch breaks are for meetings without eating.
Yes, they are for meetings without eating.
It's literally the time to just get work done, I can imagine.
It's literally the time to just get work done, I can imagine.
You're in a call while you're on another call and now you can't keep track of which calls you're in.
You're in a call while you're on another call and now you can't keep track of which calls you're in.
I can relate.
What was for lunch?
For those who ate, Austin?
Lunch is just the name of the time to not eat.
There's no contract, is it?
The contract is lunch break will be provided.
Lunch is not guaranteed. Terms and conditions apply.
It's just time to get other things done with people running after you.
It's just time to get other things done with people running after you.
It's always difficult, I understand that.
Nobody cares, you're in a training.
You're not our problem.
I think it's interesting that you shared those things with us to be joining in a few minutes.
Sure, lovely, that sounds good.
Share my environment.
Let's see as people come in.
All right, Karavan is back. Welcome back.
Thank you, thank you.
That's all right, we'll just give everybody a few minutes.
We might get one more.
Give me a second, hold on.
I can't see right now.
What's the matter?
I'll be back, give me five seconds.
Hopefully others will just join in.
Let's see where we are at.
Let's share a couple of tips and tricks.
Where is my screen? Hopefully this one.
If you could confirm that you can see the screen.
We're looking at the different ways to interact with the command line.
What I want to share now is actually some of the common tricks on the command line that generally help when you're working onto the system.
We saw earlier that we could take multiple commands.
Let's take date.
Who am I? That was great.
We could take multiple commands and run them together.
But there are a few other things related to how to work on the command line.
And this might come in very handy.
Probably the very first concept is running things in the foreground and background.
And there are many tricks around it.
Let's just give it a try.
If I run the command jobs right now, it kind of tells me that there are currently no jobs running.
What it is talking about is in the background.
Typically what might happen is some commands that take long time to execute something.
For example, if I use the command find and I'm looking for a file.
Now this command can take quite some time to execute.
Right. Because I'm doing a search across the entire system.
Now, while the command is going on, I don't have access to my terminal.
Because the system itself is keeping the terminal busy.
Anyone knows how do you deal with such a situation?
So you want to execute a command, but you want to keep the terminal available to you to do other things while that command is working in the background.
Not even as a script, just on a normal command line.
So let me explain what do I mean.
One way to explain this is to use a simple command like sleep.
Because as I mentioned earlier, literally all it does is just sleep.
You use this in script sometimes to just pause for a while.
So for instance, if I ask the terminal to sleep for five seconds, you can see it keeps the terminal busy for five seconds.
Now this could be any command. Doesn't matter.
But here the command took five seconds, for instance, to complete.
If I did ten and replace with any other command that takes some time.
Now right now the terminal is not really available to me.
The terminal is available to me once the command is done.
So let's say if I say a command that takes forever.
At this point in time, if I write who am I, press enter, nothing is going to happen.
Nothing is going to happen because it's busy executing that command first.
So some cases where we don't want to wait, we can abort.
We saw control C earlier, but that's not the ideal situation.
I don't want to abort the running command.
So what I want to explain to you is there are things running in the foreground.
There are things that could be running in the background.
And I want to help you understand how to work with that.
Step number one, just keeping a command running as you execute it, running it in the background.
So what do I mean by that?
I take a command like this.
And if I know that this is going to take time and I need my terminal, I put an ampersand sign.
I want you to notice that now when I did the sleep command, the terminal is available to me right now.
I can continue to work.
And if I write the command jobs, you notice something is in the background and it is running.
And whatever is running in the background might finish someday at some point in time, depending on what that is.
In my case, I have set sleep for 50 seconds.
At some point in time, that command will complete.
And let's see if the job is still there.
Can I request you to please try this out?
This is running a command in the background, making sure the terminal is available to us.
You might notice now the job says done and now it's clean.
Done.
This is exactly what I want you to see.
And Austin, if you just say five, it's going to disappear very quickly.
The command itself won't.
No, that was a point.
I just wanted to check something.
So I'm thinking now, in what instance would you need this to be sleeping?
Unless you're running a very long command.
Yes. So the point here is not to you.
The point is not of the command sleep.
Actually, the command sleep here is just simulating here for us something that takes time to execute.
That's it.
So the idea is you could be running any command that just takes long, long time.
And for me to simulate a command that takes long time is a command sleep because it literally does nothing but just take time.
Would you still have to specify the time?
No, any command that you execute, just put M percent at the back of it.
The command will execute, but in the background.
So your terminal is free for you.
Oh, OK. OK, that's fine.
That's noted.
You know, you know, sometimes you'll be using commands for so long whenever you want to do something, but not necessarily understanding exactly what that actually is.
This is one of those pieces.
Yep.
I've used this multiple times.
Yeah, OK.
I can see it's working for others.
So the job kind of sleeps, sleeps and then, you know, it just disappears.
So this is if you knew when you started the command that you wanted it to run in the background.
But that's not always the case.
Sometimes we just execute a command.
And then we sit there waiting and we're like, ah, now I don't want to kill this.
If I wanted to kill it, I'll just do control C.
So instead of that, I'm going to do control Z.
The difference here is it has sent the command that was running.
It has sent it to the background.
The foreground is available to me to do whatever I want.
But actually in the background, that process isn't running.
It's just been sent back and paused.
So I can continue to work.
I have the terminal available to me, but I probably at some point in time want to run what's sitting there in the background.
So I can use the command BG.
I'm hoping it works the same way on Ubuntu as well.
And you see that number one job number one.
I can just mention percentage one.
Run this command in the back.
The difference now is in the jobs, it's actually running in the back.
So in this scenario, we started a command normally.
We changed our mind.
We threw it to the background with a control Z.
Keep that in mind.
The terminal is available to us.
We can verify something is in the background, but not running.
Then we made it run.
Continue to run in the background.
Basically, we resumed it.
Please try this out.
If you have multiple jobs in the background, that number will simply increment.
It stopped.
We run jobs to see.
There is something in the background we can run.
So you have a lot of jobs already done.
Now that is number one, which has stopped their faith.
Yep.
Check jobs again.
And it will be cleaned up.
If you run multiple background jobs, you will see many.
Now, if the ones that I have already projected.
The one that I ran earlier for five seconds.
I was doing that to check how long it would take before it deceptions from.
Yeah, it's gone instantly after that done.
So now when you see number one, it's another number one.
Not the same.
Yeah, because I'm looking at this now because I see all that's gone.
It's going to clean up.
Yeah, because I saw a few seconds, then it's gone.
All right.
It's not going to show you the history of terminal jobs.
It's just right here right now.
So you will only see pretty much the current status at this point.
All good.
So we have seen two things at this point in time.
Just a quick recap.
We started by running things in the background directly.
We also did run in the foreground and change your mind and send it to the background.
What if there is something running in the background and I want to bring it to the foreground?
So let's say if I say.
Sleep on three hundred.
And one way or the other, it has gone into the.
And the terminal is available to me.
What if I want to do the reverse?
Something is in the background.
I want to bring it into the foreground.
We can generally do the opposite.
And now you notice my terminal is not available to me again because that command has.
I can again change my mind and do control Z and punch it back.
Do keep in mind though it's stopped.
If I want to run it in the background, I can do that.
If I want to get rid of.
Please try that out.
Should we check something?
I've been writing the background and.
For what?
Does it teach them that nothing is happening?
Back with you.
Tell me.
Go ahead, please.
Yeah, I was saying that I've been ready to sleep.
This is the part of the background.
But now whatever under command.
Percentage one.
That does not.
Yeah.
First, write the command jobs, please.
Are there any jobs at all?
Stop.
Two and three.
So you need to bring that one back, sir, with the same idea.
FG percentage two or three.
Look at the number on the left side.
Yeah.
Yeah.
Yes.
Yes.
We have to refer to the job ID.
Oh, that's why.
I've been wondering.
What's going on?
Why is it not showing?
OK, same for faith as well.
And then mention the job ID.
OK.
No, it's not here.
Thanks.
Yeah, I just lost a bit there.
Yeah, just do first run the command jobs.
This is for everybody.
Yeah.
So caramong.
You have no jobs.
There are no jobs.
There is nothing to kill in the background.
You run something in the background just like the sleep with the M percent sign.
Eat for long, like 200 or 300.
It simulates something that takes time and do that with an M percent sign.
If you don't do that.
Yes.
And caramong.
That's fine.
We can do control Z for you.
It will run the command.
It will stop the command.
Throw it in the background.
And if you want, you can kill it now.
OK.
Try that out, please.
Yeah, that works.
And then.
Yeah.
And terminated, as you can see on caramong and also for faith.
And for Austin, it's been terminated.
There we go.
So that's one trick.
And this usually helps as well.
So I think this is handy when working on the command.
All right.
Some of the others.
Yeah, this would be very useful, especially if you're adding scripts.
Sometimes you realize that you've got to write it out, maybe into a file.
So now it will be hiding the background to make things easier for us.
And a little bit quickly on just a few other tips and tricks.
Also working on scripts and otherwise as well, which is redirection and also working on what we call as piping.
These are, I would say, almost essential skills on the command line.
I mean, not just about what commands, but.
How do we connect the commands together?
So what do I mean by that here is.
Let's have a look.
For instance, earlier.
We did the command.
Let's say cat.
Of ETC.
So this is one command.
It produces an output.
We also know that there is another command like word count WC.
What if I was to do this.
And use a pipe.
And then do a word count.
Now word count normally is waiting for an input.
Would you agree?
If I just did word count minus L and I press enter.
What is it waiting for?
This is a lot.
What do I count?
Give me something to count.
If I say line one.
Line two.
And then I do control D.
It says aha.
These are two lines.
So the point is the command is waiting for an input.
What if I did this?
This command produces an output.
What if I pipe this into the next one?
That means the output of this becomes the input of next.
This piping becomes very, very useful with a very specific command on the shell.
Which is to filter out the text.
A command called as grep.
Here is an example of what grep can do.
Let's have a look at this file.
We looked at the file that contains all the users.
And there are a lot of users in this file.
I want to filter out any user which has no login.
That means these are not normal user logins.
These are for service accounts.
So they can't interact with the login.
In any output, I can pipe and give it to the command grep.
What do you want to filter out?
What if I say I want to filter out no login?
What it does is in the output, it only shows me those lines which contain that specific set of characters.
Think of it like a simple filter.
Takes the output and filters something in that output.
What if I want the other way around?
A reverse filter.
What do you notice now?
It does not show me any user who doesn't have the no login.
It's the opposite filter, the inverse filter.
Piping is very useful because you can chain the commands together.
And one of the very nice things to pipe is the command grep because it can filter things out.
Show me all the users which don't contain the no login.
And here is a beautiful part.
Watch this.
How many such users are there?
So what am I doing now?
Taking the output of this text file, giving it to the grep which is filtering out, and giving that to the account.
And what the account is going to tell me is that there are ten such users.
Please give it a try.
This is a quick history of my commands.
And it's not just about executing the command.
It's also you checking out what the output looks like.
Let's see if that works.
Where are the other people who are joining in some time?
I see Austin, Faith, and Karaman.
We are missing a couple of the others.
You are low again.
I was saying that you are low again.
I think you are asking us about people who are going to join.
Liz did say that she will join later.
And I think a little before she left, she did say that she might not join the afternoon session.
Can you hear me better now?
Yeah, now you are better.
Have you guys tried this out?
Does it make sense what we have done?
Yes, I tried it out.
So piping one command output into the other.
And then one of the nice things to do is to use grep as a filter, which is very, very handy.
Some simple examples of the same.
Let's say ls slash etc star dot com.
Give me a list of all these files.
It's a long list.
Do you notice there is some month here?
Feb, July, April, August, June.
So I can simply say, OK, I would like to see all of these files.
If you don't care about the upper case or lower case, just you can do minus i to ignore.
In Jan, there is only one.
In Feb, there are quite a few.
How many?
Let's do that.
So...
Give that a try, please.
So obviously, as your use case, you will start to figure out.
I think learning Linux fundamentals is the same thing.
You don't have the recipe, you have the different ingredients.
And then as you spend more and more time, then you have your own use case.
What do you want to achieve?
And then you use a combination of these commands to get that.
You just go piece by piece and then you kind of string it together for your purpose.
So it's more about like, what do I want to do?
And what's the way to get it done?
Cat slash etc slash password, grep.
Maybe you can just do minus i, Austin, if you don't care about upper case or lower case long.
And no need for wild cards for that.
It's not taking it as a word, it's just taking it as a string of characters.
You want a word, you use minus w, if you're looking for like spaces around it.
There's a long story, there is grep, there is e-grep, there is f-grep.
And if you read the help of these commands, it's scary.
Yep, that's the simplest way of using that.
Very nice.
So I'm hoping that as we are diving through this, like in the morning you guys said you are,
you have worked on Linux, you are comfortable with the command line.
I'm hoping that some of these tricks are just helping maybe close a bit of those gaps.
Or just make us a bit more productive.
Yeah, no.
This will help you because some of these commands, some of them you will find it's been running for years,
but you didn't really understand to an extent of how you can manipulate it better also.
So this is really nice.
It's going to set things up for us.
Yeah, and also if there are scripts with existing commands in it, it helps to interpret those better as well.
And we always have the case of, it's always the case of somebody did something
and then you are dealing with work done by somebody else.
And since we're all network engineers here, you know how much we love documentation.
So it's not always that readable.
Yeah.
Yes, you want a command that was used 30 years ago.
It's been passed down and passed down.
Yeah, do this.
When that happens, do this.
It's like this.
Yeah, is that control panel mentality, right?
Which button to press?
Just press this button.
Don't ask questions.
And then you wonder like what exactly does this thing do?
Sometimes it looks so mysterious.
And then once you learn what it is, you're like, that's what it does.
That is something amazing.
Could be quite simple as well.
So this again goes into the extension of your ability to be more productive onto the command line.
Now, you saw a redirection a little bit.
I'll just touch upon that as well and see how it can be handy as well.
Earlier, what we did was, for instance,
we took any command and redirected the outputs to a file.
So, for example, I can say let's take the output of date and put it into the file.
Now, that's a simple example of a redirection.
But when we do a redirection,
we have to think it in different ways.
Input as well as output.
And maybe we want to split a good output from the bad output.
Let me explain.
I'm going to run this command ls slash mnt.
There is nothing there right now, but the folder exists.
If I say ls slash opt, there is nothing in there as well.
If I say ls slash etc, there is a lot of things out there.
ls slash var, couple of things there as well.
Now watch this.
ls slash var 1.
Does such a folder exist by default?
It doesn't.
What am I going to get when I execute this command?
No big surprise.
I'm going to get an error, isn't it?
What happens if I do this?
What will this command produce?
You have a space between the var.
So there are two parameters.
One command with two parameters.
By the way, I can show you.
Both?
Yeah, I'm just saying both of them.
But the question is, is it going to execute one and ignore the error?
Is it going to say because there is an error, I'll do nothing?
Or is it going to give me both the outputs?
I think it's going to give you both.
If there is nothing on the other one, then it will go to the next one.
So what do I get?
I get the error.
As well as I get the good output.
Correct?
Yeah, correct.
Now let me do exactly the same thing and redirect this.
Into a file called as output log.
What do you expect to see in the output log?
It will just be what you just showed there.
Error?
It will not access that error.
Just one question.
If you're using two greater sizes, what's the difference between that one and the other?
We'll show you that as well.
That will just append to the end of the file rather than overwriting and creating a new one.
Oh, okay.
I'll show you that in a bit as well.
Just a quick one.
Faith, Carol Wang, still with me?
They call it as show me a sign of life after lunch.
Same as a hostage situation, right?
Where they demand sign of life.
It's after lunch and I'm demanding a sign of life.
Faith, I need to get that coffee there.
Did you get it, Faith?
No, I just went to plug on water.
Electricity just came back now.
I'll be fresh in a few minutes, I know.
Yeah, I know. I'll be good.
And mine left just before two.
Oh, yeah.
But we are here.
I appreciate it.
Please ask questions or just slow me down if it is too fast.
Yeah, I know. I think I was going to get it right because I wanted to answer this one.
That you were going to get the contents of the first part.
Yes.
But something interesting happened.
The output log only contains the good news.
Where did the bad news go?
On the terminal.
Oh, that's lovely. I run a script.
I capture the output of that script.
Everything looks amazing when I look at the log file.
Because the errors that happened just showed up on a terminal.
They were never recorded in this log.
Okay.
So if you want it to be locked also, what would be the hard command to use?
Yes, so you are just a step ahead of me.
So we're going to now break it down.
Let me stop with the questions.
No, please go ahead. It's good.
So what we're going to do is I'm going to run exactly the same command.
In which we know that it produces a good output as well as the bad output, isn't it?
But what I'm going to do now is I'm going to do this.
I'm going to use the sign 1 greater than file 1, 2 greater than file 2.
And now let's see what's...
So first of all, did you notice that no errors showed up onto the terminal this time?
Yeah.
Okay.
I think it's because of you. We have two files.
So this is file 1. What does it contain?
The loud information.
This is the good output.
That's called a standard output and this is called a standard error.
Okay.
So 1 is a specific identifier for standard output and 2 is the identifier for the errors.
I can split and redirect the standard output and the standard error differently.
Can I recommend you please try this out?
Yeah, go ahead.
I was trying the other one.
This one.
Redirecting it to what?
Okay.
Can you repeat that? Sorry.
Maybe it's possible that you can run your history so that I see that it's true.
Yeah, that's correct.
So I'm just looking at your screen, right?
LS var, var log, output.
We saw that earlier that the errors will show up on the terminal.
And the good output is going into the log file.
Yeah.
Now if you look at my screen, I'm splitting the standard output and I'm splitting the error.
By looking at my screen, my terminal, you saw 1 greater than and 2 greater than.
So this 1 and 2 are standard identifiers.
1 means the good output, 2 means the errors.
Okay.
So do what you see on my screen.
I'm here with you.
Give me just one sec.
Yes, tell me.
Is everything done?
Is everything finished?
You go upstairs and clean it.
We have to clean it for 2 hours every day.
Yeah, he's saying like that.
I have to clean it for 2 hours.
My wife has to clean it for me.
I have to clean it.
I have to clean it for 2 hours.
Clean it.
I have to clean it.
I have to clean it.
If I don't clean it, I think it won't be working.
I have to clean it.
Is it the address?
Yes ma'am.
Do it again.
So the error is on the terminal.
Yes, it's on the terminal.
So that's why I can't find it's a picture and also that the air I can be specified somewhere can be written somewhere
instead of just
Oh, okay
Austin you can be my translator tomorrow as well
Oh
That's all right happy if it is clear
Yeah, I know
All right appreciate that
So one of the things that we do sometimes when we are scripting
Is that we simply want to ignore the errors? Okay, so let's have a look
We saw that there are all kinds of interesting devices right your terminal is a device
Everything is a device
There is another device
Hopefully still there
Yeah, and any idea what this device does take a wild guess look at the name dev null
It is quite literally a black hole
Anything you send there just disappears
So I could run that command
Any command
Here we know that this command has a standard output as well as a standard error
What if I run the command and saying I'm not in a mood to seeing the errors?
By the way, that's not how you should run every command on linux, but
What happened now
And try this out
What happened to the errors?
Are they recorded anywhere are they on the screen?
Are they in a log file?
Or they are simply sent to a black hole where they disappear forever
Give that a try
Also basically you are sending that to indicate because we are using true to send whatever whatever
Yep, okay
Because sometimes we don't want to see all the errors coming up on a terminal like we expect to see some errors
We know that there are certain files which will not be found or there'll be some error which is known
So we simply want to ignore all of them also this this command you only use if you know exactly
That the response from that one is going to be an error
Yeah, or you know, you simply do not
Uh care
Generally, this is done when we have known
Challenges with a certain script we know there are some outputs, you know, one of the most difficult things in linux world in my experience
Is knowing which error
Is really critical
And some errors sound like it's the end of the world
And then the experts tell you yeah that one. Yeah that you can ignore
And there are other errors which which sound just harmless
And then they're like, oh my god, how could you ignore this and you're like, well, how am I supposed to know?
Like which error is the end of the world?
And which one isn't and and that frankly comes from from experience
So something sounds like oh my god, that's it
And then the experts come and say yeah that you can ignore. This is normal. This happens all the time
So you can't retrieve them if they're there
Sorry now i'll say you can
Well, maybe gp can't depilite so it's like you've recycled or recycled
Um
Yeah, okay that one it takes a person who understands the error because I would want to keep all the errors
So that it guides me to where the issue is
Yes, you can always refer back to it
So at least now you know how to do that like how do you take the output any errors in the output and then
You know keep them somewhere for the safekeeping and then go back and look at it
Your system on its own itself maintains tremendous
logging capability as well
All kinds of logs exist
Every component every service typically has its own logs
So there are all kinds of you know
Logging capabilities which are part of the system and that's part of learning as well
Are all available
Through the logging demons
So yeah, I think many different ways to see that
Uh
Let me see if I can show you especially on open two. Uh, the reason I mentioned this is that there are
different kind of logging
I would say mechanisms across different uh distributions
but generally
And also the path is unfortunately sometimes different I want to show you something
Uh
Log I think in these it might be in var ADM
Uh, we have the var log itself and you can see all kinds of logs are here
For the graphical interface authentication kernel logs all kinds of that as well
Uh, we have syslog can also be used as you guys already know to centralize
Any logging so we have a couple of these
Different logs for different systems available as well. There's a lot you can do here in basic
troubleshooting
Let me show you there are some commands that we can use and there are some
Uh log files that we have so your syslog
Would be your starting point
So in terms of practical how do you see the log I will show you now
Uh, there's something we can just try so there is this is like the main log file
Into an open to system some unix machines will have var log messages, but
So this is the main
Log file as you can see here. I can't access it
And I think you know the reason why
So
Just a normal user
As root I'm gonna try the same
So this is the main log file now it can be a bit scary if you look at the size of this log file
So maybe what I want to do is the opposite of cat which or more
Tail so tail shows you as the name suggests the tail of that file i'm looking at the last few entries
If you can look at those timestamps so very handy I can just say show me the last five
Entries into that log file
So
Besides this there are other tricks, but this is one so can you try this please switch to root
sudo bash
And look at the last few errors
Into your log file
Again different linux distributions maintain logging slightly differently at times
Yep, I can see everybody's trying it out
And besides this if you do know like which log file you want to look at and that happens different
Components have different log files as well
There's another little nifty little trick, which is this
I'm just gonna exit back. I have two terminals
As the same user
I am a student in both of these
And
What i'm gonna do here
I'll just make sure I am in the home directory on just to make it easier frankly the actual path doesn't really matter
So let's say I create or there is a log file
Right now the log file is empty
And let's say some errors are coming into the log file
And can you just try this bit
Then we will see the double arrow as well what happens one second
Wait, did you do something that i'm not aware of why are you getting an error while trying to get that fire pp? Hello?
Everybody
All right, does that work
No, wait, I was asking what did you do? Why are you getting an error now while trying to access that log file now?
You're pitching something on it or what? Yeah, so what i'm trying to
Showcase here. Let me just switch to my screen
So
I have a log file and what we are simulating is that some error is getting recorded into that log file
So you might have logs for specific applications or it might just be the main
File that we saw the var log
syslog itself the trouble is any file that I want to look at
Oh
Yeah, so
So we're just simulating some errors coming in through the log file
Hmm
But the trouble is I am not looking at the log file in real time
So what we normally do
Is this?
Ah, what am I doing?
Okay, and what we're gonna do now if you look at the
tail
in the options
It says f
Follow the file
So tail minus f the log file what it is going to do now
You notice that the terminal is busy
It's keeping that file open. So as new errors pop up
I'm doing this from the second terminal you watch that happening there
And what I'm going to do Austin is I'm going to add to that file
I'm not going to override that file
Here is a new error here is one more new error
And one more do you notice that on this terminal it's keeping the file open I'm watching it live
As new events happen
I can watch it happen
Oh, but you're still cheating. Yeah
So minus f keeps the file open the log file open that you can keep watching
So if you are running a script
And you are taking all the errors into a log file. You can watch that log file live
also here when you're
Redirecting just keep in mind that I don't want to override it
I want to keep what is there and just add something to it. Can you try this out? Yes boss
And keep the two terminals make sure you are in the same home directory make sure you're just a student
Just to keep things as simple as possible
Austin on one you are as root
in a completely different folder, maybe just make sure
Uh, you don't have to be in the same root, but i'm just saying just easier
Hey don't talk i'm in the workshop quickly
Yeah, what is it
Oh, yeah, come on quite try that out get two terminals up and running
And see if that works so in one you are in the backup folder austin yeah
Always make sure you are, you know, where you are at caramel. Are you trying this out austin? Can you hear me just confirming?
Yes, I can yeah good and now from the second terminal I think he did mention that about
uh
Electricity issues. I see she's not on the corner now
This is also an old
For now for the time being it's just me and is here the challenge
Is this common power issues?
It we haven't had it in a long time so
Yeah, the problem is starting at a long time
It seems okay also nuclear on what's happening now
Yeah, I know until what's happening and it was actually my fault
You gave us instruction and I kept on knowing you that
Is that the price I paid for ignoring you?
No, that's fine
You need to experiment also because sometimes when you make a mistake and then you realize why then you tend to remember it
So it's okay
That is yeah, okay
Experimentation is highly encouraged
Initially when you're learning sometimes then we recommend that you follow
Precisely what we are doing so you can see it exactly as it is but it's okay
Yeah
Because part of that then you learn like why this is not working the other guy is doing it
It's working for him. Why is it not working for me?
And then you realize oh i'm in the wrong location or my syntax not correct. Whatever it is
Just a question on this, uh, just check on this on the screen of mine here
On this terminal here. I see it says
Uh tail lock file file
Conquered it has appeared
That's because do the same thing for you
Yeah, because see what happened on the on the terminal on the right hand side you did greater than right?
So it kind of closed the old file and created a new one
I
Delivered it. Okay. Let me just do this quickly
Oh, yeah, now we took you okay. No, thanks
I think these guys are gone
Yeah, Liz is it losing I I just
from my side i'm
trying to catch up because I got a call from
the office so to drop off a bit, but
No, i'm
Yeah, i'm also not not we'll be supposed to be
But yeah, just go back to my laptop
Um, that's all right, so just open two terminals as you can simply see on my screen
And i'll just take you through it hang on give us
Okay
Okay
Okay
Okay
Okay
Okay, yep as you see two different terminals open them side to side
What we are really trying out is the command tail that shows the end of a file
The trick here is the option minus f
So you can literally watch a file live as errors or data comes into that you can see it
So on one terminal you're keeping a log file open
Uh create that log file, please if it doesn't exist use the command touch to create that log file on one terminal
And then watch it with the minus f
Faith you are also in the backup folder on the terminal that you are in
Please take a note of your current directory. I'm sorry. I didn't get that
I think in one terminal you are in the backup folder in the home directory
Okay
Keep the two terminals side by side if you can so it's easier just the way you see it on my screen
Okay, yeah just restore the window again get side by side
Okay
That shortcut we did this morning to open up a terminal what is the first one control alt t
Control alt t. Okay. I like that. I like that we are ending with where we started
Life's come full circle
Yes
Looks like you guys are struggling with power issues
I'll take uh
There will be a word document
Which contains many of what we have seen today?
As well as the deck the slide deck which summarizes the core commands and some of these core tools that we have seen
Uh, it will be in the same folder that kubeb normally shares with you
Through his cloud storage
I'll just make sure that the same link is
Active for you so you can use that as a reference if you want to go back
To these documents the other recommendation I have is that you can
History that you have
Like in my case, let me go to the third terminal
One nice thing is you can also open tabs now
You
Could if you want just take your entire history in the terminal where you have been doing everything you can save that as well
But this is just an example of watching a log file
Since we are
In ubuntu in this particular case there are specific commands like general control
These will also print out any errors
Onto the system as well
So that's a little bit of a trick on how do we operate onto the command line
How do we
Operate with lock files just keeping an eye on the errors which are going on
And obviously there are a lot of tools a lot of
Options and over a period of time just a bit of practice and you're all good
of course, uh
We have some ways to get some help as I said, you know manual pages
One way
Many linux distributions also have something called as info pages. I think man pages can be a little bit
Intimidating
Just because of the detailed nature, right? So
If I look at the the tail command here is an example. I'll just do ctrl c to close this
Uh tail if I look at the man
I'm going space by pace
If I press h there is a help of the man page itself
How do you move forward and back but man pages can be quite intimidating as well
Many linux distributions contain something called as info
And you're considered as the
The you know the the successor as well the advantage of man page of course is that also with info
If i'm looking for something specific
The output itself is so big but you can type slash and search for something
Go up and down
So there are some tips and tricks. So if I just run man without asking for
Help on any particular command
It says well
What man page do you want? Well, what if I want the man page of the man command itself?
That's matrix for you right there
And we go in and it says okay, this is how to use man page
This is how you read the manual pages and it gives you some basics
It says man page has many sections
So
It's like reading a book has many chapters
Are you shaking your manual of the manual? Yes
Because how do I use the man command well check the manual of the manual
But it is actually useful because it's telling me that the manuals are divided in many sections
Yeah
Are you looking for shell commands? Then this is section one
Are you looking of help in files? I'll give an example, okay?
Password is a command also which you use to set your password
And password is a very important system file as well. So now if I say man password, which one
The street
It says
Do you now understand what that number one means here?
That's the first example the first section which contains help for commands
So what if I say well man minus l password
I'll have to read the man on man on this again
So
Here has many sections
You can choose this one
From which section
So I can say man password dot and I can mention the section which is for configuration files
Okay
This is a long list but minus l should have worked for us as well
Should print out the topics
So yes, you're right it's a bit strange to be reading the man page of the man page
But it is useful to learning how to navigate it how do you search the man page?
How do I filter what I'm looking at?
I just tried I just tried what we have the
um regarding the man
Wherever you can specify
You can specify the section. I said the man man space password
It didn't work
Yeah, I tried man password dot one
Because it was section six that it was section one that that was showing the
But it's not showing
No, let's just check again. I think we'll just double click. Yeah. Sorry double check here
Executable I should be five I think for passwords
Yeah, oh it's five so
I don't have the one so why are you unable to pick that one? No, no, that will just make sense
Is it
Yeah
That's not what you said
Let's be men. Okay. I'll just set your screen. That's okay
Yeah, set my screen please
What did I do wrong? It's men
Oh, no, I see why no my bad as I typed out the password
Password
It's pa double sorry pa double s w d we pronounce it. It's a very bad habit
Yeah, it's built over the last 30 years and for last 30 years people are telling us
You don't pronounce that password and we say well we do
Um
Yeah, sometimes it's easy to me specifically after about that to see that okay
Is it typed out as a password or as something else?
So if the for the password it is section five because we are looking for password the file the path or the file
Okay. Yeah
And there is password the command
Which is section number one?
Yeah
Okay, thanks
But is it minus capital n one second this one happens when you don't see all the sections
Isn't it man minus k? How come it's not working. Wait a second. What am I trying?
Ah, yes, come on. Okay. Yes
So if you try man minus k it kind of lists
Like a search in the whole man pages
Anything to do with possible so you see here is password number one, this is a command
Yeah, and here is password number five, this is the five
So you can search for a keyword so here for example if I search for a keyword like this
With a minus k
So this is not searching for the command name but searching for the concept
This might be useful to you because I think sometimes the problem is sorry go ahead
No, no, no missing anything
I'm hearing things that's a bit scary
Uh, I think one of the bigger challenges in linux and unix is not knowing what command
To look for for example, yeah, because I don't know what is the command for something
So I look for what man page of what?
I don't even know. What is the command for it?
The thing with this is most of the time you'll you'll have waited to use the menu just go to google
Wherever you have all the details that you essentially need there
Sometimes you find it easy to go one
Very important word of advice for you austin and everybody else
the trouble is
When you google for it, you may not be looking for something specific to your distribution for this particular kernel version
So in 99 percent of the cases it wouldn't matter
But in one person that was once
And if you are reading forums
Uh, no, no, so what happens is we we
We do what the first guy says in the first post I guarantee you
Maybe 99.99 percent of the time. No one tells you how to undo what you just did
Yeah
No chip on taping messages there. No one responds and then you scroll 10 pages down and the guy says oops my bad
This messes things up and you're like geez. Thanks
Something
And frankly this is where
uh
Generative ai your chat gpt is your deep seat. They are brilliant
But you do need to be very clear and specific to like this version this kernel blah blah
Yeah, because also that also some of the
Exactly what you need and you might want something that destroys
So you just have to be careful also with that
So any we'll never recommend you to make any changes to any production system anyways
Yeah
Change control
All right, hopefully, uh, you can you can see man minus k this is for everybody you can search for a key word
So if you don't know exactly what command to use
It's very hard to get help on it if I say man minus k network i'm going to get a long list of things
But the good part is I see many things related to that for example here ip
So man minus k could be handy
It may not always give you exactly what you're looking for
Yes, in that case a quick google at least for the basic commands will be
So for us that is ip address
I have the loop back
I have a simulated ethernet interface. I have the v4 and the v6 up and running
The very classic, uh networking command will always work
Next step
Is not here but we can add that
Most distributions will have their own tools ip is the tool of choice
And initially it might look
A little bit confusing but actually instead of having 10 different commands. It's easier to have a single command
And just work on different objects
That makes it very easy to program as well
And scripting becomes a lot standardized
Yeah, so this kind of comes in handy
So
These are some of your interface os tricks that we can try onto the command line
And then yes from here you try as I said I I there is a reason we believe in the main page of the system
Just because it matches exactly what you have on your system
Even a slight mismatch sometimes
Between one kernel and the next kernel or one one release to the next release the files can change the configurations can change
Again we are thinking is thinking more in terms of system
Basic navigation and working on the os principally remains the same and is generally backward compatible, right? So you're gonna see
If I look at the root
Of my os
I
Can see there is a link
Well, why is that link?
well
Why is there a link
This equals to that
Well because long time ago 30 40 years ago when we wrote the scripts
They mentioned this path. Although the path has changed
We have still maintained the links
So that even your 30 year old scripts don't break they are portable so typically they try to keep things portable
So even if the os has certain changes the older locations
as pointers
Just take you to the newer location and it makes the scripts a bit more portable
Across distributions and so on and so forth
But other than that, please look for very specific documentation
Linux basics will kind of remain the same the moment you step into the system administration
As basic use is just
Questions doubt thoughts
You
Express yourself is the one judge
I just want to say I really enjoyed today
I thought that that was part of a class
It's very informative listen stop putting me on the spot
Because what I see so I had to make sure that at least I'm calling names
And you're getting back at each other are we that we're getting back at each other are we
Yeah, no today's session was very helpful
Because because this has some of things that we use are these are what we use on a daily basis
You always have to go to the Linux to check certain things are not not and although you usually have our own
Command that you normally run at least you found out you showed us
Better ways of doing them and also again, which is more important understanding what you are running true
Because you normally know like okay
This is what you run to get a specific thing, but you don't really understand
every parameter on that
On that command that you write so at least today you manage to see certain things like oh, okay
I've been running this for years, but now if you understand how you can actually even manipulate it even better
Make sure that you get the best of what you need on that
So yeah
This is gonna be only for one day
Yes, so I think the command line bit is
Yeah
I'm not so sure if that's down the line, but not so sure if it is frankly at this point in time
So I think this day one is command line basics really go ahead listen
Now once you know, are we gonna get any of this info like I saw you were sharing some slides
Oh, yes, so both of the recording. Yeah, so there is a small word document which contains like some command samples and output samples
Just to kind of summarize some of the core commands that we have seen
And the deck has a summary as well. So i'll make sure that both of these
Uh are there in the cloud storage so for you to refer it any other time later on as well
Thanks
You're meeting kobe on
Friday
Well, I wish you guys very good luck
And can I be very honest like
Maybe like if I go 20 30 years ago
You had a few choices in in your career in it used to be like you're a programmer
Like that was a very separate stream
And being an infrastructure that system was a very separate stream
And it was very clear that these paths are very separate paths, but the world has completely changed now. It's it's everybody is everything
so
I know that the journey from your network into development. It's it's a challenging one
so I commend you to be
For for being part of it and going through with it
Always good to see yeah
But I guess it's what the future is gonna actually be about anyway to make sure that we just brush up on certain skills
But yeah now now the jobs are not really like before but you know when you are
Yeah waking as a developer for example, just about development system is there you're just system is there now
You have to be able to take everything and work on everything at all at the same time
Yeah, so a lot of automation scripting. It's all embedded everywhere now
So it's almost a core skill
To the extent yeah, I wish you guys all the best for the capstone as well
You'll get the resources from kubeb as well when you meet up with him
Is there anything else I can tackle?
In the dying hours of where we are at
The graveyard shift as they call it. Yeah, it is when people go to sleep
It's that you need a lot
Yeah
Too much coffee
All right faith any questions lissandra anything on your mind
Oh, yeah, no, I just wanted to see on the file issue that we discussed here on remember when I asked you regarding
Writing because the challenge I always have
Is that whenever I want to have the same type of file?
I usually just copy it whenever it's there somewhere and I'll just copy it
But i've never been to a point where I I create it in that
Less informed as the other one for example
You'd use that for your shell scripting for example, whether it is.sh
When you create a file with the dosage it's not the same as
When you have the one whereby it's already an sh whereby it's green in color
Because the one that you create just gonna be because like you said the extensions are not really
Taking into account when you're doing this. It's about permission
Yeah, so what would be the best thing to do in the converter to create it?
Because that's why I usually flop I usually just go and copy for that
With the speech that I want that is green and then take it from there and change whatever I have to change in there
Yeah, so it's more to do with the
permission
on that file
So the idea here is that you can take anything and write a bunch of commands in it
but
What you want to do?
Just very quickly here
Right, so if I go to let's say nano
My script
And my script is quite boring it just says who am I and shows the date
Now how do I make this as an executable
So
Maybe I can execute it by giving it the full location
River slash home. This is how you executed binaries also, right?
You just mentioned the path
But if I do that it says hey you're not an executable
What if I mention a shell and call this one
Oh wait, what is in my file, but why are you not having permission to just
Check that file. Sorry. I'm just working on the wrong file
Uh, it's my script
Let me just run this under students. Yeah, I just made I just mentioned the wrong file
So home student my script
You see that works right
I had to do nothing in terms of permissions and it's not
Any separate color what it is is a matter of
Is it marked as an executable?
So if I look at this file
my script
What most likely people do is this?
I want to take this file. Oh, you're just making it executable. Just making executable. Let's see if that makes any difference
Stern green
If I mention the exact location now
That works
Or I can just call it like this
And that works
Yes
I mean
Yeah, because i've been talking I thought maybe can hear me
Sorry, can you can you hear me? I don't know why I have been muted. No
You were gone for a while there because I was asking the also I see you're having the check mark to make it executable
So it doesn't matter even if it doesn't have the sh
Yeah, yeah that that matters not at all
That is it is just so that you know as a human being that this is a shell script. That's it
Yeah, yes
Because I think that was us like I know you already told us and I even mentioned that there are no extensions on this
So right now i'm thinking I know I know the other one's always executable one of it is sh
So I think that's what usually usually just gets me on that because I'll be like why is this not executable now?
Whereby the sh is not there
Okay. Ah, okay
You have no idea how much
I
Hopefully that's clear now so you take any text file that doesn't matter how you make it
Just make it executable with that little plus x
on that
Once it's executable you can call it directly or
Yeah, okay
I was gonna ask you why did you have permission issues when you you're trying to access this
Yes, because it is not executable
Oh no, oh
I thought maybe you're trying to see the internet and you see that you're executing it
Yeah, if I do this and press enter I am saying I want to execute this just like a binary
Yeah
Mmm, it works now because I have marked it as executable earlier. It was not happy to execute it
Okay, okay now
So if you pay close attention to the output of ls minus l
Just after we have done what we have done
You see a little x
Everybody everybody can execute this
Before the script did not have the x mark
Yeah
Okay
Just do scripts like this
But it's usually each on my site
Like the basic the simple basic that you've taught us now the fact that there are no
Extensions to to linux. That's something that was every time i'm trying to
uh
To the f or whatever case it might be and it will just be failing and failing so many times
Which is because sometimes you work into these things
But you don't really they're not really taught the basic basics to say like oh no. No, just look. This is like this
So I guess yeah, that's the difference between
Uh doing something and knowing exactly what's happening behind the scene
Yeah, yeah, that's true and that fundamental helps. That's the objective frankly of the session today
So i'm glad that it has helped
Uh faith, uh, I know you said you'll be right back. Uh, listen to any questions from your end
No, nothing nothing anymore. So I guess the only question is when does this end
Yes, yes
Appreciate you guys being here. Thank you so much. Good luck on your project. See you around someday
No, thank you
How would say
Now I am done i'm going to now arrange this room every day i'm arranging this room for the last seven days
I don't know
Oh
Oh
I
Oh
Oh
Oh
Oh
Oh
Oh                

on 2025-02-19

language: NN

                  WEBVTT
keep the space open and lock it
keep the space open and lock it
keep the space open and lock it
keep the space open and lock it
keep the space open and lock it                

on 2025-02-19

language: NN

                  WEBVTT
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the right.
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the right.
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the right.
Fold the corner to the left.
Fold the corner to the left.                

on 2025-02-19

language: EN

                  WEBVTT
you
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on 2025-02-19

language: EN

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you
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on 2025-02-19

on 2025-02-19

language: EN

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you
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on 2025-02-19

language: EN

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on 2025-02-19

language: EN

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on 2025-02-19

language: EN

                  WEBVTT
I mean, I don't have the permission to do that, but I'm not sure if you understand.
Yeah, I get it. So what can I do to help you out?
It's possible to give you those permissions or just make me, I just want to see once
to determine how much money is a bit, since it's a bit more now that that is written.
You want to make it a full screen?
I just want to make it a full screen, yeah.
If you go to your far, on the right, far right, on the bottom, there's some icons there.
This one that I put out, pointing.
Others do that?
I managed to maximize my screen.
But yours is like this.
So you need to, you'll probably have to switch between mine and yours.
I'm just wondering.
No, it's fine. I'll give it a chance.
Okay. Just let me know if there's something I can do.
No problem.
All right. So we've got three terminals opened up.
Can I request you to do the same on your desktop?
Just open three terminals, please, whichever way you like.
Quick one, it's Control Alt T.
Yes.
Right click.
Yes.
Terminal and then it's a menu.
From the menu, just search for it.
Just search for terminal.
Should be able to find it.
Yeah, yeah, that's the one. It's just a graphical environment.
So probably question number one, before we do anything on this environment,
just looking at the terminal, there is a little bit of a prompt.
This prompt is very friendly.
It tells you the current logged in username at the host that you're on and the current directory you are in.
That's kind of nice.
Just to know who you are and what kind of location you have to be.
What is the first thing that should stand out to you when you see that dollar sign?
What does that typically indicate?
And please don't mind.
I will take you through some fundamentals.
I know you're all comfortable with Linux, but there are certain things I just don't want to take a chance.
So now go over the concepts, making sure that we are all on the same page.
What does that dollar indicate when you're working on the terminal?
You can always take a guess. If you're not so sure, you can say you're not so sure.
Obviously it's not for money.
So that dollar indicates you are not the super user.
You are a normal user into that system.
But that's your privilege.
We can very quickly try something on any of the terminal.
Let's do a quick sudo bash.
We'll talk about sudo a bit more in depth maybe later on, but just a quick sudo bash.
Switch and start the shell as root.
What changes into the prompt?
Last character.
So that's your hash.
And what does that indicate?
You have all the privileges.
You are a super user.
And we have another name for a terminal which has the super user.
Do you know the name for a terminal which is running as super user?
We call it as the CV updater.
This is where one mistake can wipe your system clean, forcing you to look for a new job.
What's the command?
sudo bash.
We used to actually kill Unix machines in 10 different ways.
When we were doing clustering and we wanted to kill one node to show that the other node can sustain the cluster.
And we used to come up with creative ways of killing a Unix machine.
I'm definitely not doing that here.
The bottom line is you work under root privileges when some system administration is absolutely necessary.
You do that and then you exit back to safety.
I would request you to do the same.
Let's just exit back and be a normal user.
That's just very quickly. First thing to know about the terminal, which is what are my privileges.
We're still going to explain this sudo bash.
Yeah, we'll have a look at sudo later on.
Yeah, because the way we switch to root, the first time I see it is sudo bash.
Just use sudo su like that.
There are many ways to get things done in these kind of operating systems and they are set up in a certain way.
In most enterprises there might be some differences in the way they are set up.
So question number one is what distribution are we working on?
We have to check.
And how do we check?
If you're working on a terminal, you can zoom in a bit with the control and plus.
I'm just going to do that.
Just making your life a little bit easier.
You can do the same from view.
Of course, that's the answer to everything.
There are a few things to consider.
Anyway, the first thing we probably want to do is this command lsb underscore release minus a.
Let's give that a quick try.
Yeah, because I was about to say that command will depend on the.
Yes.
So since we are currently on Ubuntu, that's what we are doing this.
And different distributions will also have multiple command and there are some core commands that you can always use.
Across even Linux and Unix environments.
Not just Linux distribution, but all the way to different kinds of environments.
How do we know what kernel we are running?
I just said I used uname mindset.
I just missed the questions.
I keep in mind many commands, especially commands like you name might provide a lot of output.
You may not need all of it.
You may have very specific things that you want to know.
This is running on Intel platform.
Yeah, great.
Obviously, you can look into the help to see the details.
Let's try some simple commands.
How long the system has been up and running.
Quick uptime.
I worked on systems with uptime is in years.
There was a funny comment back in the day to check which users are logged in.
I'm not sure if it was finger or fingers.
Yeah, it's more of like on a remote system.
It used the finger tool to get you the answer.
So a couple of different ways to do that.
Maybe the command who and who minus a might answer that question.
What does W do?
Yes.
And then you look when we are working on live environments.
We stick to one thing that has worked and that's good enough because it works every year.
We're not going around experimenting with this.
We don't have time to kind of do that all the time.
So if I don't want to see everything with you name, maybe I can just do you name minus R.
So we have commands and options and arguments.
We're going to come to that.
But this is just getting to know your system a little bit.
By the way, running commands is not the difficult part for many commands understanding the output.
Classic example for that is running the command top kind of like the performance monitor and task manager combined in the Linux world.
It has 10 million options.
But if I just run top kind of gives me a summary overall percentage of CPU utilization, memory utilization,
which processes at this point in time are eating up most of your resources.
What processes are running in the system?
When you run it obviously keeps in this case your terminal running and it is showing you these statistics live.
Why can I ask?
I see there when I, on the terminal it's got my name.
It's lucky there.
Oh, but it says student and lucky.
Because I wanted to ask why there's no name there on the student.
So I'll come back to the terminal if you see my screen.
I have just come out of top with the command Q to quit.
Frankly, this is your new generation shell which allow customization of the prompt.
And right now it is your user name at the date.
Let's find out your host name.
See if that works.
Is your prompt a combination of these two things?
And this third thing.
What's your host name?
Who you're currently as in this terminal?
Which user?
And what's the current location in the file system?
It's a friendly prompt.
I remember when we first saw this 10, 15 years ago, we were like, wow, that's amazing.
Something we enjoy a lot is a command like which and where is.
Because it has a lot of system admin.
Yes, of course.
No.
It's what which and where is.
Where is and which.
For instance, you're looking for Java, which Java C or where is Java.
Which app dynamic.
It is installed.
You need to find it in the terminal.
It's useful if you're updating Java for instance.
You're updating any application.
It's very critical to figure out the path of what we're at.
And yeah, that's a big part of system administration.
Frankly, it's mostly about the most common errors in the Linux index world is doing the right thing, but in the wrong place.
Yes, yes.
Don't give it all away.
So just some, again, just getting to know the system a little bit.
How long the system has been up and running.
What's my distribution?
What's my kernel?
Who am I currently logged in as?
Who else is on the system?
What's my host name?
Maybe we can add to that fundamental like what's my IP address?
Quickly try that.
Sorry, is there a question?
Sorry.
Is there a question or is there something there?
I have showed you something there.
So you can see IP itself as a command can be used to configure a lot of layer 2, layer 3.
And in this case, A is short for address.
So it's printing out your network configuration.
So you can see you have a loopback configuration.
You have the v4 loopback.
You're all network guys.
This is your v6 loopback.
Here is my Ethernet.
This is a VM at the end of the day.
But I can see my physical addresses.
I can see my v4.
Are we in the same segment?
Yes, I only just know there is it ifconfig.
Yeah, so classic ifconfig.
You might have to add again, depending on the distribution.
This is where the difference in the distribution comes into picture.
So I come from the historic Unix background.
I always natively start writing ifconfig and the Linux machine says, what's that?
So changes in distributions can make a difference there as well.
Also, the user sometimes, if I'm not mistaken, if you're not a super user,
there are other commands that you can't run.
Yes, of course, very true.
Just give me a second.
I don't understand why you put pajamas there.
I'm comfortable with my space here.
It's expensive coffee.
It's not really coffee.
Coffee.
Coffee.
I'm not coffee.
You are not coffee.
No, I'm not coffee.
You are not coffee.
Yes, I am coffee.
You are not coffee.
You are not coffee.
Now you are out of touch.
So guys, how do you zoom in your terminal?
Let's see.
Yeah.
How do you zoom in your terminal?
I have the same question.
I asked the same question.
I remember you showing us.
What is it?
No, it's very simple.
Okay, I'm going to zoom in on that.
Oh, control plus control.
No, yeah.
All right.
I don't know what you're talking about.
I think you're talking about the...
No, the double screen and whatever.
No, no, no.
That's just another issue.
Oh, so you don't have a double clip?
Whatever happens, it doesn't work.
All right.
So very quickly, some fundamentals.
Let's have a quick look at those as well.
So, yes, we looked at different distributions.
There are many different applications that you guys are already familiar with.
And of course, these tools depend on the platform as well.
There are all kinds of different shells.
There are many different graphical environments that you can work on.
There are plenty of different system tools.
And some of these are basically for super user, basically system administration tools.
And many of these are common tools that anybody can work on the system.
I want to focus on this first.
Basic principles of Linux.
And the first one is very important.
When you come from Windows, what is the finding?
Sir, what's the finding?
If you come from the Windows operating system and somebody talks about a file, what do we think about?
No, I hate Windows, so I'll pass the question.
What do you mean?
I can still ask the question in a different way.
What is a file?
A file can be text file.
It can be Excel file, web file, yes.
And most of the time, sometimes coming from Windows to Linux, there will be, I don't know if it's a coding or what it is, but sometimes you kind of open the other side.
Okay.
But I don't text file from Windows, but the other files are kind of open.
I'll take that one.
Now, the very basic fundamental question is still there, which is, what is a file?
Well, the answer is the right thing.
Everything is a file.
It's a small thing.
It's like storage.
It's interesting.
Because now you can stretch it to say it doesn't have to be text.
Okay.
No, so I think that as you just said, a file is everything and everything is a file.
Because there's nothing but text and files.
And the answer to that question is, in the Linux Unix world, when you describe a file, don't think about storage and don't think about date.
File is a pointer to a resource.
It's a very broad definition.
It's not just about data.
It's not just about storage.
It's not about your volume.
And it's not just about your file system.
Here is an example.
So we have, we can try this right away.
Just bring two terminals side by side.
And as I'm demonstrating this, we will try to answer a question, which is, what are the different types of files in Linux?
And the answer is not text files and PDFs and PowerPoint.
So let's try and answer that fundamental question.
The first thing we're going to do is we are on a terminal here.
I'm going to share it.
Yeah, I'm going to do that now.
Just arranging two terminals.
Remember the command we wrote earlier?
Who is in the system?
Right now it shows me on a terminal.
If I do who minus a who is well, basically everybody.
I can see there is student and student is on many terminals.
One, three, four.
So if I write the command TTY, what is this terminal that I am in?
It gives you a path slash dev slash BTS slash two.
Well, that is a file.
It's a location.
But it's not data stored on the system.
This terminal is represented by a file.
Let me go to the other terminal.
Why?
And it says it slash slash BTS one.
So that let's try a very simple command echo.
Hello.
If I do that, what's going to happen?
Then I press it.
And we're going to say hello on the same terminal.
Correct.
What happens when I do that?
What am I saying?
I'm literally saying put hello.
Send it into that file.
Before I do that, I can just say like this.
I want to create a hello file.
What is that going to do is in this current directory is going to create a hello file and I can read that file.
So all I have done here with the redirection is take this text and put it into a new file.
What does the dash in front of this output indicate?
That first dash means it's just an ordinary file.
It's a file that contains data.
What I'm going to do right now, I'm going to send hello there.
Can you please try the same?
From one terminal, send hello to another terminal.
Find out the identity of the terminal with the command pty and send it from one to the other.
Everything I do, I would recommend obviously that you try it out as well.
Sort of the two screens there.
You can see it.
So what about your last thing for the going hello into depth-dts2.
Well, which terminal are you sending it to?
Please first write pty on both the terminals.
We have two terminals opened up side by side.
Just look at my screen if you can.
That's fine, at least two.
Everyone okay with this?
So everything is a file.
So with that in mind, coming back to my screen share.
Let's have a look.
ls minus l del ptst.
What is the first character in the output of ls minus l?
Compare it to the ls minus l I did for a file I created which contains some text that was started with a dash.
This one says c.
Any ideas?
This is what we will call as a device file.
Device files can start with a c, start with a b depending on whether you read character by character or these are blocks.
So it's a special file.
This file represents a device.
A device is not a hardware.
A device is something that needs drivers.
So in Linux, your terminology is completely changed.
Third, let's have a look at the root file system.
So we're going to do ls minus l.
Let's put a forward slash.
Say we want to look at the root file system.
I want to see the top of the tree or the bottom, however you want to say.
Notice something here.
Bin points to usr slash bin and look at the first character.
That is l, which means what type of file is this?
That's l.
l here would mean this is a link, like a shortcut.
This is the third type of file.
I repeat, there are ordinary files that begin with a dash.
There are device files that begin with a c or a b.
There are links like shortcuts.
They begin with an l.
And what does the d indicate here?
So a directory is also a file.
So l is a link.
I've never seen l.
Is it a matter of connection?
Yes, a symbolic link.
Is it a matter of connection?
Do you need certain permissions to say it or is it just normal?
Nothing special for you to see.
The majority of the links in the system are just to maintain backward compatibility.
So scripts that were written 20, 30 years ago, sorry lucky, scripts that were written 20, 30 years ago,
they pointed to slash bin, will continue to work even if the binaries have now moved to a different location in the new Linux Unix systems.
But a script that still says slash bin will continue to work 30, 40 years later.
So the majority of the links are system built.
You will see later on how to make them and how to use them.
Lucky, go ahead.
No, I was just saying it's like written as a shortcut.
Yes, it is.
It is and it isn't.
We'll look at symbolic links and see how it is slightly different.
We have soft links, hard links.
Okay, so a very fundamental question we would like to answer, which I hope that we have, is this.
His comments are exposing me. I thought I had no Linux.
Do you know Linux by any chance?
Yeah, Linux, I work on it, very difficult.
As I said, it's not so difficult to get started, but to truly understand what you're looking at.
And then in Linux there are three levels.
You have users, you have administrators, and you have engineers.
So engineers are above administrators in the sense that they understand under the hood behind the scene how the system functions.
And administrators can do the admin work and set up a platform and set up the user and services and all that.
So there is the third and the fourth level in this, which I totally understand.
I don't do a lot of that these days, but we used to spend a lot of time with high end systems.
I spent 20 years on Solaris as an OS, and we used to do kernel tweaking and tuning,
and we'll have people coming in 10 years of experience with a lot of confidence saying, I know Unix.
And then after five days they said, I don't know Unix.
I thought I knew I don't. And that thing is true for everything.
There is a next level for everything. That's just how it goes.
And these systems can be complicated.
A quick look at what I'm sharing on the slide.
There are four types of files, files that contain data.
Remember, they have a dash in front of them when you do ls-l.
We have directories. Directories are also considered as files.
We have devices. This slide is incorrect.
Devices are not for accessing the hardware.
Devices for accessing anything that needs a driver, including hardware.
And we have links. We're going to see more of the links later on.
But on the OS, we can understand the different file types
by looking at the output of ls-l.
ls-l
slash etc password. This is what kind of file.
So when it doesn't have a normal file, yeah, it's a data file.
So remember, this could be this could be an image.
This could be a PDF. This could be a document.
Please understand that in Linux, there is nothing called as extension for the file.
We put the dots and the three characters at the end,
A, because it makes us feel better.
B, because certain certain applications will make some assumptions.
But technically in the Linux unit, there is nothing called as extension.
So when you look at a file with a dash in front of it with nothing at the end as a dot text or whatever,
how do I know what is in it? Is it an image? Is it a PDF?
Is it an executable file? Is it a binary? Is it a script?
How do I know? That just tells you it's a file.
But what type of file? Is it PDF? Is it a document?
We use this.
Can I please request you to try exactly what you see on my screen?
It's a binary. So what kind of binary it is?
Okay, so is it more like, because in Windows you always expect an extension.
You don't have an extension. It's a different type of tree.
So here it's more like, basically a file is almost,
we say it's an object that contains information about the resource, like name, size, link, the file type and all that.
The logic is very, yes go ahead.
By changing an extension, you're not changing anything.
Because there is nothing called an extension in the file system. It's just a file name.
So how do we see the metadata of the file? More like when was it created?
LS typically will print everything about that.
As you can already see with LS minus L, permissions, UID, GID, sizes, date, time.
So typically LS command will do all kinds of things for you.
Not really. Not really. That's not the reason for it.
It's the kernel architecture itself, which is slightly different.
And anyways, I don't want to get into this, but each OS has its own vulnerabilities.
So architectures make a big difference as well.
So I would again request all of you to please try this out.
I can guarantee you Linux is very easy to watch, very difficult to do.
Sometimes when you see something, it looks very straightforward.
When we try it, things may not always work out.
So I hope we have at least answered some core fundamental questions.
What's a file? What are the different types of files?
How do I know what type of file I am working on?
Or I should be working on as well.
We'll get into the commands a little bit as we go through this.
But this is also where we would like to just get comfortable with the file system.
And that's another bit, which is depending on the Linux distribution that you're working on, some things might be different.
But generally speaking, if I would like compare it to Windows, you have the Windows folder and you have the programs file folder.
There are certain locations where we expect certain configurations to be.
In the Linux Unix world, half the battle is trying to figure out or remembering what is in which folder.
These don't matter too much for an end user working on the command line, but they probably do matter if you're a sys admin.
Then you need to familiarize yourself with many different locations.
The starting point, the top of the tree, is what we call as the root.
And under that, there are plenty of different folders, each containing some specific type of files or configurations to be found.
So, for instance, under the root, the ETC folder contains a whole lot of confidence, hundreds of files where all kinds of configuration exist.
For instance, let's say, again, as network engineers, I would like to check this out.
Cat, read a file, and I want to read the host file.
And all this is, well, it's the host file.
In Windows, you find it in C, Windows, System32, Drivers, ETC.
Guess where the ETC folder on Windows came from?
So a lot of the Windows hierarchy as well that you see also comes from Linux and Unix more or less.
So the host file, for instance, in Windows is in System32Drivers, ETC folder.
Same place I see the host file here as well.
So different locations matter in the file system.
For instance, if we have a look at the root of the file system very quickly.
I see boot, MNT, proc, run.
There is a temp space.
There is bin, sbin, opt, where software packages are found.
Home, which is the location of the user home directory, which is currently, I mean, as a student.
So my home directory is under slash home, student, desktop.
As you get more into system administration, then you spend more and more time on, or in this particular folder, what exists in that particular folder.
And you become familiar, frankly, with a bit of time.
There could be small differences between different, I would say, distributions at time.
But on a high level, it's kind of something like this.
Sorry, GP.
There's another question.
I think I should have asked you when we're doing the echo.
Hello.
If, for example, I am an admin and I want to see into which terminal is using, how do I do that?
And then I can send that message if I just want to say, hey, if you stop watching this.
So, so first of all, who minus a will answer that question for you.
Who minus a will also show you remote users who have delineated or SSH into the system.
You will see everybody local as well as remote logged in users.
Even as a normal user or as root only or as super user.
No, we can do both. Who typically prints out all the information?
It should be.
Some binaries are limited if they're not running under super user account.
Some binaries are for everybody to use.
And lucky what happens is in many organizations, they want to strictly limit the privileges of even a normal user account.
For example, why does a normal user account need to see all the running system process?
That's a classic example.
So what we normally do is we then harden these systems and there are different mechanisms by which we do system.
Creating restricted shell and so on and so forth, limiting what commands you can execute.
So then like I think what I'm trying to say is so that an operator who has specific tasks doesn't do anything beyond those very specific.
But it takes some work to do that kind of hardening.
So in many cases, an end user might be able to do a lot more than maybe we really wanted them to.
Hopefully that kind of answers the question.
Yes, yes, yes, yes.
All right. Any other questions from anyone else at this point?
We have it all good.
How about the others?
I know when we started, everyone said you guys are intermediate on Linux.
So I hope this is not super basic.
But as I mentioned, I just don't want to take a chance.
Yes, no, don't take a chance.
Now we can see where we are.
At least I didn't say I'm in TBL.
What is that word that I will use?
Intermediate.
Comfortable, comfortable.
So hopefully we are making you uncomfortable with your comfort level.
Yes.
Yeah.
Yeah.
So that's the reason I'm just going through some basics that I think I don't want to take any chances here as well.
We'll work on the file system in a little bit.
Maybe a good time for a short break.
Fifteen minutes and then we resume.
Yes.
Yes.
All right.
Good to have a point person.
We like outsourcing anyway.
See you guys in 15 minutes.
Ninety seven.
You.
You.
You.
Had some coffee.
Apologies if I haven't mentioned, I'm based in Dubai.
Oh, just like Kobe.
So we are colleagues.
I've known him maybe 10 years now.
I'm based in Dubai.
I'm from India.
I've been in the Middle East since the late 90s.
Dubai, I've been here since 99.
So you've been to Asia before?
I haven't.
I mean, you know, Manla is there and every time there is a client engagement that physically requires me to be there.
And the clients change their mind at the last moment.
You are too expensive.
Let's do this online.
It's definitely on my mind.
There are some parts of the world I don't really go out of the way on my own.
Since I know that as part of some engagement, I'll end up there someday.
So I think this is one of those places where I know I want to be there, but I know I'll end up there one way or the other.
I had a couple of my family friends with recently and they went to some beautiful, gorgeous places.
And it was just very tempting when I saw that I said I need to go there.
Beautiful coastal locations.
They look really nice.
Yeah, for sure.
Everyone here is in Cape Town.
Joburg, where are you guys at?
We're in Joburg.
So half of it is Joburg and some of it is Pretoria.
Because Budapest is Joburg.
I see.
I work with people all over the place.
Lesotho as well.
Specifically, I've been in Africa.
I've been to Egypt, Ethiopia, Kenya, Tanzania, Zanzibar.
But that's about it. I just need to go down a little bit more.
And it's almost in that order that I have traveled.
How about the others? Are you back?
Winnie, you've been very quiet in the first half.
Yes, I'm back.
I'm the quietest in the entire group.
Okay, fair enough.
You've been outed, Winnie.
Taki, how about you? Are you with us?
Yes, I'm here.
I'm just listening to Ivan.
He likes Cape Town.
I don't know why he didn't tell you he likes Cape Town.
He's bad.
I'm sure now it's not long I'll have a picture of myself.
He is bad.
Good to have you back with me.
Let's soldier on.
So that was frankly the first half.
Just getting to know some fundamentals of the Linux.
What we want to do next is just get a bit more comfortable with the file system in terms of the structure.
How do you move around?
I'll give you some tips and tricks on this.
As I said, partly the challenge is doing the right thing but just in the wrong place.
So we're going to focus a little bit on just moving around the file system.
We spent a bit of time just knowing that there are different types of files that was a starting point for us.
Ordinary files and links and directories and so on and so forth.
The first thing probably on any table, as I mentioned, is just figuring out where you are at.
And that would be a quick PWD.
Print my working directory.
And that will just very quickly tell you where currently in the file system you are.
As I did mention, we have the root and everything under the system.
All the resources are available under the root.
So we can just do this CD forward slash.
And that means I'm on the top of the tree or at the bottom.
But all system resources are available under the root in terms of the file system.
And here we can again validate that with a quick print working directory.
Yep, I am absolutely at the root of the file system.
And all the resources are under that.
What happens if I just write CD and press enter?
Would it accept that?
It takes you to your home directory.
Quick shortcut to go to your home directory is that.
Just write CD and press enter.
Can you see what character represents your home directory?
That's the tilde.
Tilde represents your home directory.
It's what tilde?
Yeah, tilde.
Linux makes you reacquaint yourself with the keyboard a little bit.
Okay, is it the one that we use if we want to go to the directory that we wait?
Say CD tilde dot dot.
Oh, you said you have to put dot dot.
Yeah, so tilde simply represents your home directory.
So what is my home directory?
Right now it is slash student slash, sorry, slash home slash student.
Correct?
Let me change my current directory now.
Now I am in the root of the system.
Let's say I want to create a file in my home directory.
Do I have to go into the directory first?
Not necessary, I can just mention the path.
Yes, but before you can go there, I see up there the first three lines.
You see there's that tilde and then slash desktop.
What is happening here?
Under my home directory, there are many folders.
Oh, okay.
One of them is the desktop.
Desktop, okay.
How did I start this particular terminal?
Most likely by right-clicking the desktop and say open in terminal.
So then it opens a terminal and the current location in the terminal is the desktop.
The desktop is just a folder under my home directory.
I have documents download because it's a normal user account and all kinds of other things.
Are we okay with this?
Tilde represents your home directory.
As a shortcut can be used for the same.
Now, when you're working on the file system, we mentioned that there are two ways to move around.
There is something called as the absolute path and there is something called as the relative path.
Let's just look at that with a quick diagram.
I'll just share a quick whiteboard to represent that idea.
Give me a second.
And then we will use that to move around the file system a little bit.
So in terms of how do we move around and how do we mention the path, let's say we've got the root.
And then under the root, I have the folder home.
Under home, I have the folder student.
The root, I also have the folder who are here.
So the first thing is, what's your current directory?
So let's say my current directory happens to be slash home.
Absolute path means anytime I mentioned the path and I begin with the forward slash.
The moment you start a path with slash, you are referring to the top or the root of the file system.
And then you have to give the path according to that.
If you're not starting with this, then you're starting from the current.
What do I mean by that?
If I'm in the home directory and I want to go into the student folder, there are many ways I can do this.
One is I can just say CD student.
It assumes that student folder is relative to my current location.
It will work.
What happens if I say CD slash?
The moment I say slash, it doesn't care where I am anymore.
I need to provide the complete path in the file system.
Slash home slash student.
So you can use relative or absolute path.
In many cases, like scripts and all, we want to give the exact path where something is.
Sometimes relative is just faster.
I don't want to start from the root every single time.
All right, let's give some of these things just a quick try.
I'm going to just share my screen and do exactly that.
First, I'm going to go into the home folder.
You can not find this out as well.
After you have a quick look, I'm in slash home.
Will this work?
No, because you started with a slash and you're already at home.
There is no such folder under the root.
If I start from the slash, then I must say slash home slash student in the full path.
Don't forget the shell is a little bit friendly, so you can use tab to autocomplete.
Tab is your friend.
It helps us eliminate typical typing errors that we can have.
If I know that one very well, then I like the tab.
Of course, it's more productive and less errors.
The less we type, the better it is.
Now, from slash home, how do I go to slash what?
What's the question?
From slash home, I go to slash bar, which is another folder under the root.
You have to say these.
So if I start with slash means I'm giving absolute path.
How do I do this relatively?
So what will this do?
Level up.
So what is that?
That is the root, isn't it?
Over home.
Then I can say slash what?
I climbed up and then climbed down.
Okay.
Now I have a question for you.
Please watch my terminal carefully and look at my current folder.
I am under home.
Under home, I'm in student folder.
From here, how do I go what?
Relatively.
I know.
Absolute path is simple.
Please give it a try.
If you are here, because I see you are on the slash bar.
If you want to go to that path that you are coming from.
Another way.
Just looking for that.
CD8S.
Oh, I thought this thing.
What do you call it?
That thing that represents your home.
Until death.
No, CD- is simply a way to quickly jump between two locations.
Current location, last location.
Glad we have answered that.
Thank you very much.
So.
So CD- is just a quick way of jumping between two locations.
You can obviously use dollar, sorry, tilde.
If you want to specifically refer your home directory.
It might be faster.
What's that going to do?
It's going to create a file on the home directory.
That's just much faster.
Vinny, I don't see you trying things out.
Okay, I can see you're doing things in the terminal.
Akona, are you trying things out?
Hi, sorry, sorry, sorry.
I got distracted there a little bit.
I'm doing that now at 12 o'clock.
All right, welcome back.
I can see Lucky is doing the same.
Okay, so creating a file.
So creating a file called new file, right?
Yeah, just in terms of what's happening.
Look at my terminal.
Start from the top.
We are just trying to navigate the file system.
Using absolute path and relative path.
Absolute path.
We are starting with the slash.
Relative path is from where we are at.
We are using something like dot dot to go up or tilde to refer to our home directory.
Just moving around the file system.
All right.
No, no, no.
That's fine.
That's fine.
I appreciate that.
And just writing cd with nothing takes you to your home directory.
Yes, yes.
And cd space dash helps you hop back into the directory you came from previous location.
Okay.
So cd dash will help you hop between two folders, one and the other.
Okay.
Back and forth.
So new file already exists.
That's okay.
That's okay.
You can just touch dash that tilde new file.
This is just to show you that tilde refers to your home directory.
Okay.
Okay.
Okay.
Can I request everyone come back to their home directory, please?
So dot dot was the parent directory.
Now let's look at this command.
Just for instance.
I want to copy this file.
Copy is a command.
And it needs some argument.
Have argument.
How many arguments are needed for the copy command to work?
We need to copy to the destination.
So we need a source and a destination, isn't it?
So if I just write copy slash etc hosts, it's not assuming the destination.
This is not enough.
Yeah.
Where is it going to go?
How do I say here?
Copy the file where I am right now.
Hopefully that makes sense.
Dot means here.
Dot dot means in the parent location.
Bring me the file where I am at right now.
Okay.
So there's no default.
For instance, it doesn't provide a default.
If you leave it blank, then there's no assumption.
It doesn't default to anything.
I thought it was going to default to the current.
Yeah.
So if you can also use the tilde.
Yes, of course.
But maybe it's just not in the home directory.
I am somewhere else.
Dot simply means in my current loop.
Dot does not mean my home directory.
Okay.
I get you.
So dot is here.
Yes.
Wherever that here happens to be.
Are we a little bit more comfortable with the file system?
Dot dot dot slash.
We are starting from the root of the file system.
Yeah, yeah, yeah.
Yes, yes.
I feel comfortable.
I'm becoming comfortable.
I think what we hear, I'm not sure if I still get into it.
One thing that took me, when using the CP command and the tilde,
was copying from one server to another.
Then you need SCP.
Which is very useful.
SCP, I'm assuming, is an extension of CP.
Yes.
So secure copy between hosts.
Secure copy between hosts.
The colon and tilde at the end.
Yes.
Or just use the tilde for the home directory.
Yeah.
So hopefully this adds a bit more clarity to it.
Yes.
All right.
So that's again the basics of the file system.
Other things to note about the file system is if you want to just see what are the different,
I don't want to say partitions, but what are the different file systems.
We can do this command df minus h.
H is for human readable, very kind of them.
Because otherwise, good luck with the calculations on how many blocks.
So someone somewhere said, well, actually, humans need to understand it.
So we have df minus h.
And it kind of tells me a little bit about my partitions on my file systems.
How much space is there?
How much is used?
That's kind of a little bit handy.
What is a little bit tricky sometimes is understanding the folder size.
Let me explain.
If I do ls minus l to start listing the file system, first of all, I'm in my home directory.
If I do ls minus l, you can see like I see some folders.
I see some files.
If I do ls minus l.
Now, you know that let's start with home directory.
You know that under slash home, we have home directories of many other users.
So we start from here.
I do ls minus l home.
And it tells me that there is stool.
Now, the question is, what is the size of this folder?
Right now, what does it say?
But let me do one thing.
Let me go.
This is just a demonstration.
You don't have to do this.
I am in my home directory.
And if I just look at some of the files that I have, that should be more than four.
These are all directories.
Directories just show 4K.
So what might be difficult at first is just to figure out.
Well, actually, what's the size of the folder?
There is a tool called this du.
And typically most commands, if not all, support the argument dash dash help to give you some help.
Sometimes the help is so big that we simply Google these things.
But I have this du summarizes the use of the set of files.
And we have this one minus h print.
And I have summarized minus s.
Give me a total.
So what I'm going to try now is du minus sh slash home.
That is better.
Slash home slash student.
That's nice.
What about the etc folder, which contains configuration files?
Ignore any permissions denied.
Because we are a normal user.
So some files we can't get to.
That's around 18 MB.
So this is a quick command to understand the folders.
Because this doesn't show up in LS minus L for a folder.
In Unix, we used to have MK file.
I wonder if it's here.
Yeah, it's not here.
And this is just for me to try things out.
Oh, we do.
OK.
Equals to big file.
The current location is block size five.
Nice.
By the way, I've just created a file of a certain size.
This is for the advanced people.
DD is literally copy.
Guess what that device does.
What do you think that device does?
They have zero.
Gives you no price for guessing.
It gives you zeros.
I'm actually reading from a device that gives zeros.
I'm putting them in output file in the block size of 500.
And I'm repeating that 50 times.
Please be careful with this command.
I have now created a 26 KB file.
What if I repeat the same thing?
Make it five.                

on 2025-02-19

language: EN

                  WEBVTT
Okay, I'm back. I'm back. I like that I have to prove I am a human every time I come knocking.
And someone once said, it's funny that robots are asking us to prove we are not robots.
Isn't that true? It's a machine which is saying, hey, prove to me you are not a machine.
Let me just share my screen again.
So we'll just, you don't have to try this. But what I'm literally doing is just creating a file made out of nothing.
But now I'm creating a file as you can see.
26 KB. I'm just overwriting anyways.
And now it's 2 MB and one more zero. And now I have a 26 MB file.
Created in my home directory. I can repeat that command.
Give me a summary.
Hopefully you can see if you execute the same.
That now you're taking more space in your file system.
So nice handy command. Give me a summary which is human readable.
Just careful with the spaces.
Anytime on Linux.
Careful with spaces.
Does it work for you? You don't have to try this.
But just showing you the output of TU-SH.
Just with the file systems.
All right. So we're comfortable with just some of these fundamental commands.
Maybe I'll add to this.
Good old LS.
Which is the first command that we looked at.
Just how to see what's in my file system in that particular location now.
LS has lots and lots of options.
If I do dash dash help.
I have plenty of options with LS.
The one that we just tried first was LS minus L.
Gave a long list.
It was a little bit handy.
We could see permissions.
You can see some basic information.
Date timestamps.
The type of file all shows up there.
There are many ways to do this.
Give me the size.
Give it a reverse order when I want to do some sort of sorting.
T sort by time.
And everyone has their own favorite LS command.
For instance.
We created a file.
Earlier.
Called as my file.
What if I create a file with a dot in front of it?
I take a list.
And I really.
I don't see it.
Is it not?
It is somewhere there.
It's there.
You're going to see everything.
You do LS minus A.
Give it a try.
So with the minus A, a lot of things that have been hidden come out.
So LS minus A kind of literally means all show me everything.
What that means is if you create a file with a dot in front of it.
It is hidden.
The file system.
Unless you see it with a minus.
I think.
Assuming that works for everyone.
Yes.
So the lot of hidden files and for different purposes.
But that's one.
If you just put a dot.
Now comes one more very interesting thing.
I create a file called as new backup.
And now I need a folder.
Would it let me create that folder?
Yes, because one is a file and the other one is a.
And what is the directory?
A type of.
So back to my question.
Would it let me create this folder?
No.
In Linux you cannot create a file and the folder with the same name in the same location.
Because the folder is also a file.
So this message is a bit confusing, isn't it?
I cannot create a directory because a file exists.
This hopefully now again gives us some understanding of the file system characteristics.
Hidden files navigating around in the file system.
Referring to parent directories and current directories and absolute paths and relative paths.
The fact that multiple files and folders can exist with the same name.
How do you know what mount points exists?
How do I know what the size of my file system is the folder so on and so forth?
And again, commands like Alice have hundreds of options as well.
So we have Alice.
We have CD things that you've just done.
The other thing that might be handy as you work on the system is again just knowing who you are and where you are.
So come on like I.D. is very useful.
What is your user ID and what groups you belong to?
Obviously determines your privileges.
We saw the who am I.
It says you are a student.
That's the user that you have logged in as the current terminal.
That's where your privileges are.
To find out what's the current time, what do you type on the terminal?
So time doesn't tell you time of the system.
Time tells you the time it takes to complete some task.
Yes.
So I switch from my user to an application user.
I run commands.
I want to know who run those commands.
I'm according to user or user Tomcat.
I switch to Tomcat and I run certain commands.
So the short answer is I've understood your question.
I believe.
Let me prove that here.
So what I'm going to do is I'm going to do pseudo bash and I'm going to ask who am I.
Right now, what does it say who am I?
Root.
Now the way system accounting works, basically the way logging works.
It's not just keeping track of this.
It's also keeping track of the real user from which you switched.
So right now, who do I?
How do I know what user I really, really am?
Because right now I have just switched to a shell which has root privileges.
So you say, who am I?
But this time you shout.
This is shouting at the system.
Then it says fine.
You are students.
Oh, OK.
So if I were to search for who am I.
So this is you.
I try to remember which user you looked at.
Which user you switched from.
Yes.
Now.
So I guess you need to manipulate the system command to.
So now you have.
Now you can root.
It will show you the commands.
But it does.
Let us know.
I think in terms of what you're trying to do is simply called as auditing.
And there is a system accounting that must be configured.
And it will keep track of the real user.
This these are none of this is auditing.
None of this is accounting.
What you need is a system level log file.
That kind of does this.
In the Unix world we used to do Hulu.
In the Linux and others.
You just have to set up accounting to do that log.
OK.
Then you can maintain that historic log.
So just you guys try the same.
The who am I and who am I.
After you run the shell with root privileges.
Just checking all of you are still with me.
Yes.
Akana you around Vinny.
Yeah.
All right.
You're all network people.
So I'm bringing you to see if there is a timeout.
Looking for latency and if ICMP is coming back or not.
When you ping what is the ICMP type for equal request and equal reply.
That's a question.
Yeah it is.
What is the question?
When you ping you're using the ICMP protocol.
What is the exact type code for the equal request and equal reply.
Code.
Yeah.
So it's a type 0 and type 8.
That's your equal request and equal response.
I did my.
I started my career as a network engineer in 1994.
Things changed.
In 1994.
We were waiting for the.
Besides.
We were.
We were.
What kind of.
We.
We.
No.
No.
Some kind of.
So I worked on.
Your task.
IBM.
I work on IBM systems and OS tools at that time
We didn't use TCP IP protocol. It was IPX SPX on novel that way
It was routable as well
We worked on MTS tax x400 and x500 for directory and communication
And then TCP IP kind of came later as the internet started to became more popular
They're like what's this TCP IP thing? Nobody will use it
And then the rest is history of Kuta
All right, there's a little bit of
Who am I?
Just telling you
Who you have signed up as and in the system, what are you recognized?
So that's just some basics
Now yes, since you're working on the file system
Request us to kindly exit and come back to our home directory
Then we
It's
Still within the terminal of that was set up homes
Yes
And that's where you add the dashboard so that you get the complete environment
Basically all the not hidden files which contain a lot of configuration is loaded as well
Space SU dash or the pseudo minus I
Yeah, you're doing pseudo as you yeah, it's the same thing here
Switching to root
The idea is we don't want to completely switch to another user we can just
Restrict you for certain commands. That's where sudo is very handy
Okay
Hopefully that answers that question
Since we are now, you know, we are navigating the file system a little bit
It's also a good time to just manipulate the file system a little bit very quickly
We saw the command touch creates a blank file. There's nothing in there
You can create a folder
With mkdir you can create a complete folder structure
With a minus P I won't back up
Logs
You see doesn't give me any errors the rest of the path is already created
It helps me quickly create the structure so you can just do touch to create a blank file
And you can do mkdir to quickly create a couple of files
Can I please request that you make folders with the similar naming as mine just so that as you follow
The commands coming after this you don't have to keep adapting it to your directory structure
Yes
And nothing has root we are happy to run this as a moment
This is for everyone these do the same
So that's making folders creating a file
Copy
It DC host now, that's a single file
Let's copy it in that location
Let's copy
Multiple files with a wild card anything that starts with whatever but ends with a conf
Let's copy it the other location
If
It finds any folders it doesn't copy them
It's copying only files get into that
If I try to copy
Logs
Logs
It says I don't like copying folders
And what it suggests if you know work on folders mention minus I
Recursor the whole structure
What if I copy the same thing over and over again
Doesn't care right it's just alright then good or bad
Some will argue it's good. It does exactly what I want to need my nanny
I
Hope I like my side you know, then you should not be a says admin some will argue
Yeah, the problem is between the chain
Yes, it's the network layer we say this is with layer layer
When I used to be on service desk that the joke we would have saying oh, it's a layer 8 problem
If you know, what's the layer 8 well the layer above the application?
People wouldn't understand it like huh. Yes, it's between the chair and the desk
It's called as the OSI layer 8
So it doesn't mind just quickly overriding
If you don't want that to happen
We'll discuss this later on but we can do a minus I
And minus I is a little bit more friendly
It's a bit more interactive and it says hey you're gonna overwrite
You can pick and choose whether it's something that you desire a
Couple of file system
Options you can copy
Multi-compiled into the same destination
By default it just overrides
Assuming all of you are giving this a try
In comes
The command to move or rename one command does both
What does that mean
How can it move or rename?
so
First of all
Data file
MV
Data file now careful with the destination if I say
MV data file. This is the source the next argument is the destination
If I say MV data file data file one, what is it going to do?
Yes, so there is no file called as data file one right now data file doesn't exist a data file one
There's not so all is going to do
Is
Just going to rename this to this
So I know MV sounds like it's a command to move but it moves or rename depending on just one simple factor
Does the destination exist?
If the destination exists is gonna move in there
If the destination does not exist, it will simply
Rename here is another example
Try this one out. I'm gonna say touch file X
I'm gonna say MV file X but this time I'm going to say BKP
What do you think is gonna happen? Do we already have a folder called as BKP here? Yes
So, what is that going to do is it going to rename file X to BKP or is it going to move it to that?
If the destination exists, it's a move
So does it look like copy and yes
No, no, no, it's just a move you're moving this file into that folder. Oh
If the destination does not exist it will simply rename this
Let's have a look at and let's file X
Hey file X is not here anymore
It's gone there
Please try this part out
Create a file move it to a folder watch it disappear
I was not even going to
CP will copy
Okay, just a ping
To live many hops crossed minus one making sure it's not zero
Again, yeah, please do give this a try it to with us trying things out
Okay
Just a little bit of file system nice to know how to do that as well
Of course at times you might have to get rid of things my screen
We can always do that RM
In this case not many questions asked I've created a file I've removed a file
What happens if I say get rid of
All
Let's see what is in that folder
There's something in there
What if I say this remove everything under that folder
That it doesn't mind I use a wild card question marks for one character or you have star for all matching characters
You don't know that one is easy
It wise that folder go ahead. So quick question. Why?
Because that's a folder so it doesn't like deleting the whole
It has no problem removing all the files in the folder you're gonna get rid of the folder and
Minus
I
Any open files yeah crash and burn that's all I
Want to delete I don't care about the rest of you on
Please give this a try and you can now see
I
That's your little bit of file system, how do we get rid of things?
I
Am is kind of very handy if you want to remove only empty folders this command comes in
It only leaves empty folders
Kind of like a safer approach only going to clean those files
I
Think we are all good with this
We'll continue on with some more tricks in the file system itself and that
Is about links you might remember we said there are four types of files
Ordinary files device files folders and what we call as links. Let's have a look at links
So what I'm gonna do here
I'm just gonna take hello and put it in a file
My data I will read this file first of all, this is
Just a file that contains ASCII text
LS minus L kind of proves that to me begins with the dash
so
I know that it's a regular file right and I can read it very quickly
I'll wait till you do this and then we will do the links business in a bit
Now let's try something let's create what we might think of as a shortcut or a link
I'm going to use the command and
To create a link we will use this option called as minus s called as symbolic link
So this is the original file my data
and I'm gonna create a
Link called as my data one
Let's have a look at
The details a little bit
I think you should notice that
Can you tell what is the original file and which one is the link
Hmm and it tells you also right my data is my data one is pointing to
My data so you're very clear. One is the shortcut. The other one is a real fine
I can work on both the same way
Do you notice the link while you're working on it? No, so same thing when you're working on a folder it could be a link
also
You wouldn't know
Yeah, you just wouldn't know yeah, of course it's gonna show you the whole part absolutely
So if you look at the root you will see that slash bin is also slash user slash bin
When you use the command LN you will mention the path and it will tell you the same
What happens if I get rid of
The original file so to speak would it let me delete it or it will say no you have a shortcut
I couldn't care less what happens to the shortcut of the link
So here the shell is very friendly showing you something in red color I wish things like this existed 20 years ago
But when you try to use this file
I
There's no
As long as the path is satisfied it's happy
And I just request you to try this again everybody
Then it fixes itself back again soon as the requirements are met. All right. Now we're gonna do something slightly different
Let's talk quickly about the idea of hard links
What you saw right now is what we consider as a soft
What exactly is a hard link let's take a look so I guess the analogy for a hard link will go something like this
let's say we have a room and
This room has
Two doors
You have door number one and you have door number two
So if a room has two doors, how many rooms do you have
The someone can come in from door two and somebody else could come in from door one, isn't it?
Yes
But you actually end up in the same room
Yes
Put some table there
You
Access the same resource, but you have multiple doors
Would it matter if we closed one of the doors?
Would still there be a way to access the room?
Yes, and
We could always add more doors, isn't it?
Yes, how many doors do we need operating minimum to have access to the room?
No one as
Long as there is one door. We are happy we can get it to do
This is the idea of what we call as hard links. Let me show you
Here is file one
Here is a link this time
But at least somebody noticed that it would be worse if I go on for half an hour
That's fine so we are like a minute away
So here I have just created a file you can do this after you come from the break just watch my screen for now
So I've created a file I'm gonna do the link come on this time there is no option minus s
Let's see if that makes any difference
I already have fire. So let me just create another one
Okay, I'll call this as the blue file
I'm gonna make a link
To the red file
Let's notice something interesting
Do you see anything different here and the way the links show up then what you saw earlier
Does anything say that it is a link to anything else?
What's that number guess what is that number
Remember my diagram on the whiteboard there are two doors to the same room
Let's watch the blue file now we haven't done anything something happens on the blue file
What have we created we have created the third door
What happens if I remove the blue file typically we will assume that this is the original file isn't it
Yes
But the other
You know
Look for the identity of the file we call it as the I know number
What is common between these files
This is the room number this is the room number
These are two doors
This is called as hardly feel free to try this out
When you come back from the break it take an hour
So let's resume and I think it's
1 p.m. Your time. Is it correct?
Let's take an hour whatever the time it is for you, I think it's two hours difference any questions on what you see on the screen before we
Have a look
No anybody else all good
Of course, yeah. Yeah. So the key is pay attention to that that problem
All right, see you guys back in an hour i'll probably disconnect and let me in
See you guys enjoy your lunch
Okay
Welcome
I can hear you can hear me. Hello, can you hear me?
So
Can you hear me
For a tv today, can you just check i'll give you the number can you hear me
Oh
So
Say number
Exclamation yeah, I have registered two numbers. This is the alternate number
No, yeah, it was supposed to be today I've been calling on the last two days I said it's due today
That number is all up
Go ahead
So
So
So
So
Surrounded by
Showing the apple
An ideal for small spaces
Maximize functionality without supervising complex
What's the home
So
Here is my new office space
Oh
As soon as I pulled the desk away from the wall
So
This
So
Since this is technically
It's not so I have to come up with ways to make it seem like it's actually
And one of the easiest ways to do that is to add some mirrors. I added one right here, which is a rectangular
Full like mirror basically and another one right here
And chose to fill up this large empty wall with an equally large rounded mirror to soften the design
Having such a large mirror does give you the illusion that you are in a bigger room
This time I definitely wanted more storage space so while keeping with the industrial feel and design I added this
I found this industrial style shelf at ikea and it's called the
You know what? I'm not even going to try it to announce that I considered this corner an expression of my mother
Photography and fictional giant and maybe not so giant robots
And this shelf also serves as a storage area for my lenses my cameras and also some of my bags that sit
at the bottom shelf
And here's another name that I can't pronounce but I do love this chair
I think this shelf has a lot of character and is quite affordable and also pretty easy to build
Although it may take me a little bit longer to you know, assemble this just because of the limited space that I have
And also because I messed up the first time
And the second time one of the benefits of having this on the layout is that I am still able to maintain
Eye contact with my guests if I have them over for a podcast recording because this monitor arm is
Adjustable I can basically just move this out of the way so I can it's not awkward
I'm trying to look at them behind them under
Well, it's maybe slightly a little bit because I can't really see you're actually not allowed to touch it
It's just that I can't I can't really see you anymore
So on this side of the room is where I keep my podcast equipment so come take a look for podcasting
I'm using the rhod pod mic mounted on a PSA1 go mark alongside probably one of my favorite pieces of tech
Which is the rhodcaster pro. The rhodcaster sits on top of my new filing cabinet full storage and convenience
Along with my magsafe charger i'm using rhodemate's wood magsafe stand with a brass finish
It glides perfectly in space and is also very comfortable
Mounted underneath the desk is the drop amplifier alongside the cowl digit ts3 plus for easy access
For listening to music I still like my sanheiser 58 xp release that I got from drop.com
And it sits on top of the rhodemate headphone stand from lolite
I also mounted my satetsu desktop charger underneath the desk as well as this headphone holder that I found on amazon
I know i'm mounting a lot of things underneath the desk but it just keeps everything a lot cleaner
And speaking of keeping things clean I have to briefly talk about how I manage my cables using ergonomysis cable management solution
And if you look at their website, it looks like I have it on backwards, but I actually prefer this for a good reason
Since I have an audience in this way if anyone should sit in front of me
I don't have to look at any of the nasty cables
I even have my m1 that can be mounted underneath the desk so that all the cables are just nice and clean and hidden
And since all of them are basically connected to the power strip
I just need one cable that runs down the leg and to the wall
Which means if I were to raise or lower my desk none of the cables get tangled or pulled
Regarding the desk itself. I'm still using my same ergonomysis suede desk at 30 by 60 size in dark walnut
And I just really really love this desk
I also added this very fluffy area
So
So
So
To me
Here with you, let me know if you're around
I think maybe we
Now most of the guys they will come in here for just one minute. It's all right
You can wait before
You don't know you won't say I wonder what's for lunch
So that
Yeah
Um, so it's five past three in the afternoon
Based in dubai. Oh just like the baby
Oh
So he's on my team
I know him for many years
It said yeah, it's too hot that side
Yeah, it depends on your definition of too hot. So
Anything from 25 degrees that's our winter
And i'm not joking it is winter right now and it is 25 degrees
Our summer starts at 40
Yeah
38 would be considered as pleasant
The the worst I have I mean it can reach 50 here as well
Peak of the summer you expect 42 44 kind of on a daily basis
It can be 40 in the middle of the night
At dubai being
Coastal so, you know it gets humid as well
So that's more of a challenge than the heat
And the worst I have seen is 56
56 yeah
I was in iraq for a few months and i've seen 56 i've seen like 44 at 7 in the morning
So 25
Yeah minus five
Here we don't know what is a minus
It's not part of the mathematics that we learn give me one quick second i'll be back and then we'll get started
Oh
All right, i'm back
You have the gardeners and the lens capers and everybody
Offering services all the time
All right, assuming everyone's here with me, uh winnie
i've um
All right, all right, so welcome back
We are on a journey in the world of linux
Hopefully we have seen a few things we haven't tried before
Any thoughts on what you have seen so far just in terms of linux fundamentals
No, it's good it's quite exciting because there's actually
Uh something very close to what we do on our
So knowing the ins and outs and what these simple
Commands for what we need to be a simple command actually true or mean
Friendly is meaning the end
That's good to hear so as as we can see that we might have done some of these things before
There might be some gaps here and there. It's just nice to know
Uh some tricks around it. All right, let's see we can continue to work on
our environment
We'll just see how to edit files
And then we will move our
How do we work on text files because a lot of if you are doing administration to some extent
There is some file editing looking at the configuration. That's quite common
as well
And then we will move towards
like tips and tricks
on the shell the environment itself
There are a few things that we can do i'm gonna switch back to
My
I do have the same presentation deck as well as a small word document which kind of summarizes many of these
I'll make sure that Kobe passes on to you as part of the materials that he typically shares in the cloud
So you'll have access to that as well in case you want something just as a reference
And you want to look back at some of this content and other content as well
So you've seen a few things the last thing that we saw was
Hard links if you haven't tried the hard link part, I would recommend please do so
Before lunch if you didn't have the opportunity, please try it out
Just so that it's not missed the key is that when I created the symbolic link with the command
I did not do minus s
And that's what makes it a hard link because that minus s is missing minus s
Symbolic link or a typical shortcut as you see
Is that when you do that ls minus l you see that number increment
And we equated that to doors of a room
As long as one door is open you have access to that particular resource
Give that a try
Let's see just giving it a try
Out
How come you've done the same
Hi
Welcome back
Let's ask if any questions
I want to
It is that sometimes we might be building on something so that's all
Is this
I don't know if you have ever tried this command. I just popped in my head as you said taking notes
I usually like this command. I run the command for the script give some log file
Now what happens is everything I do
The output
Of the command as well as the output
Let's do exit
And now I have a log file
Which contains everything I did
You wouldn't know
It's just like a screen capture of sorts
That's a good one
Yeah, sometimes you look for the help for something and then
10 new words pop up and then you go into that rabbit hole and you're like, you know what? Never mind
Yeah, just take your word for it and thus create a time script
So
Just kind of what it does here is this
if I say
script my log
Pretty much anything that I do from now on on this terminal
The output of and the commands will be captured into that log file
So if I say hey show me what's in the opt folder well it's blank
Uh show me
You name minus a
Okay, that's the system details
Who is on this system? You know, i'm just typing a bunch of commands with some outputs coming in
I do exit
Now it has stopped recording this
Terminal session
And the command I had done earlier I mentioned a log file. So let me read
That log file
And it kind of has the output of what I did just saying
You don't have to do this, but it's a nice way sometimes just to keep track of what you are doing
And to keep track of the output
Of the commands
If you want to go back
All right part of
Since we were working on the file system
I think part of working in the file system, especially in the linux unix environment
Is working with text files
A huge part of our system configuration is stored as text files and historically
Making changes to the system configuration required editing some sort of a text file now
There are the classic old school text editors which are terminal only not based on a graphical interface
Tools like vi and then we have the friendlier tools like nano
Or gedit and you pick whichever editor you are comfortable with take an example
Nano
My
Okay, and in this case well that file kind of already exists nano notes
And an o notes
So here is a new file
Editor and those carrot signs basically are the
Commands that we can give out
Exit I can save it if I do ctrl x
Just do you want to save what you have done
Yes, what is the file name i'll keep it as notes
And i'll now create a text file
Give it a try
Yeah, so we are again very classic very powerful but at the same time a little bit complicated
Some people might prefer a friendlier version
Vi person as well. I don't use a lot of these editors
Maybe I could then we have commands like gedit and many other editors. It's a it's a text editor at the end of the day
So it's a text editor I would say at the end of the day just pick the one
So this one is default
You would see nano in most if not necessarily all
I think these days you're gonna see nano almost
And that's where if you're not sure you go back to
Something like vi for instance, just give it a try. Yeah
How to save and and you have a control x
Control x
So it will save automatically it'll ask you most likely
Oh, okay
Save modify. Okay. Yes write name to write notes
Okay, all right, okay, so so so just a quick question when saving
um
that name
That originally was created example loads now
And give a different file name as well, it should just say well likely as a saver
As
I think somebody muted me there. So what I wanted to find out is just change the original file name
Let's just create a copy and then
Yes
You can add anything
Add something and then exit save and then here if you just change the
Rename or just create a different copy
Um
It asked you right so if I said yes, then I probably end up with two files
Okay, now try opening loads
Because we did the file save as right
I'm just reading the file
So
That's like file save as right
That's the new file
Let's get into that just after this so you're one step ahead of me
But yes, we're getting into that just after this once we create some documents
Cat is good for things that show up on a single page more allows you to read large text outputs
with more capabilities
Typically by habit I just do more
I do cat when I know that it's gonna fit within one page
Okay
Everyone okay with this?
Okay
All right
Here we go
So that's just an example of a text editor
When it comes to reading text files, first of all, just a quick reminder
Use the file command to see
If something is a text document if I want to read it I can always use cat
Which is technically to catalog and it just prints out the file onto the terminal
If you're working on large files
You probably want to work on the command more
For instance, the password file is a big file has a lot of users defined into it
So with more
As you can see it has now paused on one single page. I can scroll
With the space bar or the key bar the enter key enter goes kind of line by line
And space goes page by page
If you are reading a long document
And you found what you're looking for
You don't have to read through the rest of it. You can just press q to quit
More is also handy because it allows you to search for something in the output
So we can kind of do a quick filter and look for something
within that document itself or the text output
So it is very handy. So if i'm looking at more right now
instead of pressing enter or space
I can just put a slash and type something i'm looking for
And it kind of
Scrolls is not the friendliest tool in the world, but it kind of scrolls to bring that part of the page where
What you're looking for is there you might still have to hunt around
Looking for it exactly where that is, but it just brings that part
Uh
And onto the screen so many things can be done with more
If you just press h for help
While you are doing more it tells you there is a lot you can do
You can fire up vi from the current line you can go forward and back
It's just plenty of options. There's a very interesting one. I want to execute a command while i'm reading that file
That's kind of nice
So if i'm reading a file
I don't want to exit go to the shell and come back to this file
I can just do exclamation mark
And run a command
I get the output right there
I can still continue to read the file
So this can be handy if you are like reading some configuration file and you want to make some changes
But don't want to hop in and out again and again
Very powerful very useful. This is more so
So here if you already in the file
Yeah, you see with with the pwt you're only checking pretty much where you are at the moment
But uh, are you only I mean, what are your limitations here can you
Just run whatever whatever you run will just run in a sub shell. That's it
What do you mean by limitations? I'm not sure so
So while opening this file
Can I arrange?
Just randomly forget that I mean
It just brings you back it executes that one command and brings you back into more it's hard to forget
Oh, okay. I'm still in this fine
Yeah
So
Just can be useful
Every command has so many options in this platform. So everything boils down to what you need
When you need in terms of capabilities the terminals brilliant the shells allow you to do a lot
All right. Hopefully that answers the question. That is more
In many cases you don't want to read the entire file so
We have cat which kind of reads the file which we saw that but we also have tac in lelex
Which also reads the file just in the opposite sequence
That was the last line now here it has become the first line
So it just reads the file but from bottom up
Sometimes
You want to see the last few entries first
Okay, that is
Some way of doing everything
So you can read top down you can read bottom up opposite of cat
Uh, you can also in many cases we do use this we can just read some specific lines at the start or at the end
typically we use command like
Give me the first five lines
From host or the opposite head and tail give me the last five lines
So it can be handy if I don't want to see everything but just the start or the end or a text file
I know what i'm looking for
Give it a try very simple one
And then tail
Other things that you can do again, so this is still working on the file system specifically working with the
text files
This kind of works
And we have tail
Uh, we have another one that can help us sometimes
In certain scenarios where we we need to know how many lines
are there
The command i'm talking about is called as word count
And it is called as wc so if I just run this command word count and if I press enter
Uh, it just gives me nothing but a black screen. So what i'm doing here is i'm going to type a few things
this is
Another
We have one two three four one six seven eight nine
11
11
words
Now that i'm on a blank line i'm going to close this file
The linux unix shortcut to close the file is control d
d for delta
It is end of file I do control d and word count is counting this text
And it is telling me I have three what?
Three lines three lines 11 11 words and 50
50 characters in total
Uh and remember as I said sometimes you learn things and you're like when am I ever going to need this
Maybe I just want to know how many users are in my machine
Okay, count the number of lines in that file
Well, I know that each line is a user
So I can quickly tell I have 50 users defined in this os the use cases come over a period of time
Some you never use
Some you do this is word count
Simple tricks, but they can be quite handy as well
All right. So now from
the file system
Let's move more towards
The shell environment and some tips and tricks around working in the shell environment
We are comfortable with text files with the directories with manipulating with editing
With moving around with symbolic links
Let's now have a look at just some of the tips and tricks in terms of how to use the command line
The very first few things we need to know is what you are executing
where it is
And how to create aliases to make your life that bit easier
Some of you already mentioned that come on for example, which
Wc, where is this?
Executable the location of this
Executable is in user bin
basically the binary files for everybody
That location
means a common system tool
Which I be
This tool or executable is located in s bin
Or single user super user basically means it's a system administration tool. So what we are executing
On the shell as commands and executables can be in different parts
for example
When I do cp
Copy something
Copy is located
In the usr bin. So that means a common
binary
For system when I use the command cp
Let's say
To copy the files
We saw this earlier that cp doesn't care if we are overriding a file I did it twice
No questions asked anyone remembers how to make cp ask us in case we are overriding something
Minus i
So
It would probably be very nice if every time
I ran the cp command that actually replaced it with the cp minus i that would be nice
And this is what we call as creating an alias
You execute the alias and it is substituting it for something else. How do I do that?
Just like this alias cp equals to please pay attention to the spaces and the quotations
This is single quotation. I'm gonna say cp equals to cp space
Minus i
And now if I copy again just like I normally did earlier
Something happens
It seems to be replaced with a cp minus i
Can I please request everyone to try this out? I can see vini is already doing the same
Would this be just locally for you your machine or even if
Lucky accesses
Even look at terminals, I have another terminal open here
It doesn't seem to be caring about that alias
So your terminal is a programmable environment in this case what we are simply seeing is programming it temporarily
Specific to that terminal
And then if you want any of this
customization of programmability to survive
Then as a user there are a few hidden files in your home directory where you can make some of these things permanent
And as system admin if you want to make some changes like this for all the users
Then there are some other configuration files that you can work on
So that way you kind of make it more persistent system-wide. This is temporary
programming of the terminal
Okay, so as you can see the other terminal couldn't care less
Wherever we yeah back to
This one
So what we can do here
Is run the command alias just to see do any aliases already exist
And
Looks like it does there is some alias is L is actually LS and LA and LL
And you can make your own aliases for any commands that you like. Just pay attention to the quotations
And then there is no spacing here
Between the alias and
And there's a command that replaces that alias itself
If you don't want the alias, it's fine. We can unalias it but before we go                

on 2025-02-19

language: EN

                  WEBVTT
I don't care if they allow it or not, just take one.
I'm back, I'm back, I'm back.
I just accidentally killed the laptop.
I'm back here with you.
Now, hopefully you're still here with me.
So we just made an alias for CP.
What if I want to execute CP without the minus i?
Right now, as expected, the alias is working.
So right now, it's a little bit annoying.
I just want to run CP as it originally does, not the alias.
What happens if I directly refer to that path of the executable?
Would the temporary alias or the alias set still be an effect?
Looks like not.
If you directly point to the executable, it ignores your alias.
If you don't, your alias is an effect.
Give it a try.
When you hit a CP, you can see CP on its own is replaced with CP minus i.
So the alias is working.
What if we didn't want to run the alias?
Run the command from the actual path.
You can set up aliases just to make your life easier.
You don't have to remember complex commands every single time you want to run them.
Just a quick alias and the software will work for you.
Are we okay so far?
Very good.
Some other basic tricks onto the command line.
Just getting comfortable.
You can execute multiple commands together.
Simply put multiple commands separated by a comma.
A semicolon.
And it can be as many commands as you want as long as you separate them.
Yeah, it should be.
Guess what the sleep command does?
Quite literally puts the terminal to sleep, isn't it?
Okay.
Just introduces a little bit of a delay, that's all.
Useful in scripting and other scenarios.
Now right now, between these two commands or three commands or four commands, there's no logic between them.
They are simply separate commands being executed.
What if I want to execute the second command only if the first command is successful?
Or the other way around.
I only want to run the second command if the first command fails.
We're going to give this a try.
I'm going to create a file x, y, z.
Now you know this from experience.
What would happen if I did this?
It's not going to let me do it because there is a file with the same name.
By the way, what happens if you use the command touch and the file already exists with date?
It's not going to override the other one.
No, it just updates the date and time stamp of that file, last access.
It's a non-destructive command.
Similarly, if you say touch for a folder, all it does is just update the metadata.
It doesn't do anything destructive.
But in this case, I have created a file first, isn't it?
And now I'm going to create a folder.
If I do this command now, cd x, y, z, or cb slash hosts to x, y, z.
It just stops me right there, doesn't it?
So there I cannot create a directory.
Another example, if I do this and say create a file a, b, c.
Now we know that the first command is going to fail.
Has it created a file a, b, c?
What does this prove?
So it proves that if one command fails, the other one is going to fail.
No, it won't execute.
Yeah, it won't execute.
It's a conditional connection between the two different commands.
If I remember correctly, and that's a big F.
Is that that?
Let me just check.
Let's say b, c.
Oh, I do remember.
Yeah.
If you put two pipes together, it's the inverse logic.
Is it the inverse?
Oh, okay.
Only if the first command fails.
Then execute.
The second one.
Oh, okay.
I would request you to please try this out.
Continue working on this concept of chaining the commands together.
And working with the output of commands.
I'll give you a few minutes.
Just give this a try.
Ivan, you're comfortable with this?
Yeah.
All right.
Give it a quick minute for people to try this out.
E2, all good?
Yes, all good.
All right.
Let's continue now.
And look at the idea of chaining multiple commands together.
And what I mean by that is taking the output of one command and using it as an input of the second command.
Just a quick reminder.
We did this command earlier, wc.
What is it waiting for?
This command right now.
Maybe for you to terminate or you have to write and then terminate, then it will terminate.
Isn't it the file that it wants to be taken from?
So it needs some input, isn't it?
Simple words.
It needs some input.
And then it does what it does.
So to terminate, when you type it does, we have to use Ctrl D.
Yes, Ctrl D.
Ctrl C will abort it.
So you come to an empty line, a blank new line, and then do Ctrl D.
Ctrl D is technically called the end of file.
And the trouble is sometimes when you're reading websites or documents and they say EOF.
And you're like, what is this?
What do I do?
Because you literally type EOF.
And you're like, why is it not working?
I'm typing what the guy says.
Because there is no way for them to type the keystrokes.
So this is how they are represented.
So here I'm going to do this.
Ls minus L for slash, let's say, yeah, of my current folder.
So I'm going to do Ls minus L. What I'm going to do now, I'm going to put a pipe.
And literally the pipe is acting as a pipe.
It's going to take this output of Ls minus L and it will pass on that output to the word count as an input.
And now word count is counting the output of the first command.
It says, hey, you have 41 lines and so many words and so many.
So this is the idea of piping.
You can carry on piping.
You can take the output of word count and give it to another command and you can change them together.
The most common reason in the Linux Unix world when we are piping is because we want to filter the output and we are looking for something specific.
Let me explain.
For example, let's look at this file ETC hosts.
There are many lines in this.
Some lines contain the word localhost.
What if I wanted to see only those lines?
So typically you can use attune grep.
I can say grep.
I am looking for localhost in this file.
I have to say Winnie and E2 are the fastest at doing what I'm doing.
Sometimes I get confused.
Am I watching my terminal or somebody else?
I can predict the future.
I look at Winnie and E2 like is that me with a delay or I mean it's just too fast.
What do we get?
It has kind of filtered out all the lines that contain localhost.
It's only showing us that.
I can do it the other way around.
Inverse with a minus V.
I don't want to see any line that contains the word localhost.
It goes the other way around.
Minus V.
The way I use it is not the way I know it's useful.
I use it to show when I'm running.
Maybe I'm executing something so that it can show me what it is doing.
So be very careful here Lucky.
Options are different for different commands.
Every command has its own options.
So minus V for one command doesn't mean the same as minus V for the other command.
In many, minus V stands for verbose.
But please don't make that assumption.
Every single command has its own options.
You have to read the main page for it.
This is specifically for grep.
Now let's combine a few things together.
For example, ls minus l slash etc.
Now this is a big, big output.
These are all the files in etc.
I specifically want to look at all the configuration files.
In etc.
I only want to see those that are updated, let's say in February.
I put a pipe.
Grep and give me a quick second.
Hang on.
Hello.
Yes boss.
From.
Why are you calling me my friend?
Thank you my friend.
Thank you.
Sorry.
So I say grep.
I include minus I because I don't care about uppercase and lowercase.
I will simply.
Say feb.
Some kind of filtering out.
And I want to know how many of these are there.
As you can see the pipe is one of the most useful tools.
Allows us to chain multiple commands together.
Pick one.
Yes, I'm familiar with the pipe.
What did you say the semicolon was for?
Just to run multiple commands at the same time.
There's no chaining between them.
Okay.
That's fine.
This is the gravy art shift.
It's a happy time for a trainer because people have no questions at all.
And if you are doing any workshop in person.
The moment you look at somebody they just shake their head in anticipation saying all is well.
Don't look at me.
I have no doubts.
Here I can just monitor who's typing and whose terminal is blank.
Hopefully this is.
The point.
Go ahead.
I like that I can I is the the translator between me and others.
He's acting as.
I'm not sure if you are acting as a bridge or a switch or a router or a gateway or a proxy but.
Well.
It's more like a layer to amplify it to me.
So that's that's basically the idea of connecting and chaining the commands together.
Frankly comes in very very handy as well and things like that kind of work as well.
Quite well.
Talking about connecting commands together and.
Working on files.
We saw this earlier when we did a little bit of this.
And we did that.
So what does that greater than sign represent.
It says it's like a redirect.
You are you are sending these to a file.
Is that.
So this.
Is not the first line.
Of the file.
Always on the on the first time.
You are redirecting the output.
OK.
Somewhere to some device.
Let's just say that.
However.
Let's pay attention to that.
What happens if I run a command.
Like this.
So what is the folder that exists.
So I get some output.
And war one is a folder that does not exist.
And I get some.
What would happen.
If I did this and the command takes multiple arguments.
What am I going to get only the good only the bad the both nothing.
That will be very nice.
Very convenient.
I like that.
I get both.
I get the other.
As well as what we call as a standard output.
So there is a standard error.
There is a standard out.
I get them both.
OK.
What we're going to do now.
We're going to repeat exactly the same command.
And I'm going to say this.
What do you expect.
To be captured into that lock file.
Sir.
Everything is good.
First we ran the command.
We saw everything on the screen.
On the terminal.
And now I'm saying OK let's run exactly the same command again.
And I want everything to go into that lock file.
Watch what happened.
What do you see on the screen.
This cannot access.
So that's the error.
So guess what's in the lock file.
Only the good news.
Oh OK.
I was not expecting this.
The output.
Of.
That directory.
That command worked.
Slash var.
Is successful.
OK.
So that output is saved into the lock file.
Is this the output.
Yeah.
Of course.
Yes.
The error is on the terminal.
So the error is on the terminal.
The good news goes in there.
OK.
So what's this now.
Same command.
And let's see.
Will explain in a bit.
But see if you notice any difference.
First of all what's different this time.
Here there is one.
Two.
And what's showing up on the screen.
Do you see any errors like you saw last time.
No.
OK.
Wouldn't that mean.
So what does lock file one contain.
No.
Lock file one contains the good output.
Yes.
And you can.
Yes.
So.
It's not the first output or the second output.
One is a special number which means standard output.
And two is redirecting the error.
So one is the code for the good output.
Two is the code for errors.
Yes.
No I do.
So my question.
Is that correct.
Is that.
I thought.
So you said LSD.
AR1.
VR.
So VR and AR1.
And then you said.
So.
Then you said.
One.
Must redirect to lock file one.
And two must redirect to lock file two.
First and the second.
No it doesn't.
But that's not the case.
Now you know.
I can see your screen.
No.
It's not there.
OK.
No.
No.
I can explain very simply.
If I just say MKDIR.
I'm in a current folder.
OK.
Let's say I make a folder called as data 100.
OK.
What happens if I repeat the same command again.
So that's an example of an error isn't it.
So this is what two greater than simply represents.
Any errors are redirected.
In the case of the first one was the command successful.
Yes.
OK.
So if I take an example again I say make directory 101.
It worked correct.
Yes.
What if I say echo dollar question mark.
This is a special command.
How did the last command exit.
What was the code.
Exit code.
Exit code zero.
It exited without any errors.
Yes.
Basic programming.
I run the same command again.
What was the exit code of that command.
That's an error.
So any time you're doing redirection one greater than simply means without errors.
Two greater than means any error.
The reason I'm showcasing a single command here is because I can show both good output and an error from a single command.
Tell me is it is it always based on the last command.
Yes.
Yes.
No. No. No.
What do you mean one and two based on the last command.
So you see a lot of command.
This is this echo dollar question mark is the exit code of the last thing that ran in the time.
Now let's do something interesting.
Slash bar which we know will work successfully.
And slash bar one as well.
We're going to do something.
We're going to redirect this to.
I'm going to do something here.
What's going to happen here.
We still don't have bar one.
Yeah. So we will get both the outputs.
The good output will go into the good log.
Fair enough.
But where is the error going.
The null.
And that null is a black hole in your operating system.
Even light cannot escape it.
So whatever you throw there never comes out.
It disappears in thin air.
So now the error.
So I don't see it on the terminal.
It's not recorded into a log file in a file system.
As you said is garbage.
Please try this out.
You can see Winnie has already tried it.
Winnie you are right about being the quietest one.
I mean in the training session.
It's an alias.
Oh it's because it's not conveyed.
It's a stranger danger.
Type.
Just type.
You have a terminal.
Just type.
All right.
Hopefully you can try this out.
And hoping that this makes sense as well.
As to how do we redirect the output.
And in this case sending some part of it to them now.
Please tell me one thing.
So if you.
So if you're saying one.
One.
The output of the code output must go to code log.
Don't need to create.
Don't need to create code log as a file.
No.
Only one thing to note.
And that thing to note is.
If you keep doing this.
You will overwrite that file.
Redirection.
Unless you do.
This is going to append at the end of the file.
Yeah.
I wanted to ask if it applies here as well.
Just be careful with that.
Append otherwise.
That can happen.
You can accidentally just use the redirect again and then.
You look at the file and you're like where is everything.
You just wiped it clean.
So just be careful with that.
I can see people are trying.
I'll give you the opportunity of course to try everything out.
That was the intent today to keep it as a workshop.
And obviously.
You need to spend some time with the OS yourself.
Most many networking devices and systems have underlying Linux.
Minimum you want to go there.
Look at some log files and stuff like that.
So hopefully you feel more comfortable doing that.
When I started with my life in IT.
Back in those days.
There were only three options that people understood.
Related to IT.
Either it was hardware.
Or software.
Or multimedia.
And I had a hard time telling people I'm a network engineer.
Nobody understood.
I'll tell them I'm from the network and they're saying yes.
So which one hardware software or multimedia.
You had to put yourself in one of the buckets.
Scroll up.
Scroll up.
I think that's all there is here.
Happy to show you the history.
You can try this out.
This is for everybody.
Just run the command history.
And any command you want to execute.
Just put exclamation mark and put the command number.
Wow.
I'm just saying I thought I know how to line it.
I mean you would always assume that since you are comfortable with it.
You can get certain things done.
Yes.
I can understand why you would say that.
The commands he knows are enough for the work.
The tasks that you do.
The specific tasks.
I don't know what that is.
Yes, but I was using the wrong commands to do certain things.
In fact, I was just doing five steps.
I was just doing one step and then I'm done.
So hopefully that works out.
We can see the append with the greater science twice.
A quick look at the history and then executing the commands.
So there are lots of tricks, frankly, on the shell.
And that's kind of what we are aiming for here.
Come online comfortably and knowing how to get certain things done.
Or maybe understanding how things happen in the background.
And then these could be very handy as well.
So this works now as you are working with the log files and the file system
and we are looking at how to append.
One thing just comes to mind.
And that is when you are specifically if you're working with log files
and reading some log files, what comes in kind of handy.
Let's have a look.
I'm in the same folder just to make my life easier.
And two different terminals right here.
So if I have a log file and we have seen a couple of log files,
like here is the log file and we saw that we could add something to the log file.
If I cat or more, whatever, I will see that happening.
But I can actually watch a file live.
I can keep the file open, text file open.
And what it is going to do is show me as new entries come into that log file.
So very handy if new messages are getting recorded.
So I keep tail minus F. You can see here it's keeping the terminal open.
This command I can tell you here.
All of us, we use it in the database.
You're masters of this.
That's holy. I'm sure I'm not holy.
I'm sure. With all these tricks, maybe this is something.
Because already I'm seeing the number of lines one, two, three, four, five.
Why does it always return five?
Is that the default? Can we change the number of files?
But it's doing echo there.
You see redirecting to good log.
I'm just adding more into the file.
It's just watching the file live.
OK, that's one.
You can always control C out of it.
There are a few other things.
Frankly, I haven't tried them on Ubuntu.
Is there a command watch? Oh, yeah, there is.
Very nice.
That should work.
Watch two minus eight.
It's actually repeating the command every two seconds and showing me the output.
So Dale was showing you the file as data enters into that.
Who is just repeating the command over and over and over again?
So. If I open a new terminal.
Another terminal.
The number of terminals incrementing.
Let me just read this a bit.
That's number six.
I wonder why not.
I'm not sure of my other terminals.
Let's try something very simple.
Alice.
And let's just create a file.
It works.
I will just check some options.
I can see the file X show up now.
Let me find why that shows up there as well.
It takes two seconds, but it shows up.
This was there back in the day in the UNIX world.
But here we go.
You have a command that watches other command execute and update.
That might be handy.
Instead of you manually running the command every time.
So the difference here between Dale minus F and Watch is the two.
No, Dale is watching a file.
Showing you data coming into the file.
Watch is running a command.
Repeatedly.
Any command.
That's fine.
You mean the interval?
No, I think I get it.
So if you're just entering a file over and over and over.
That's what Watch does.
It does this every two seconds.
Now don't look at the command ls.
Watch can be just used for anything.
Watch the date.
Don't equate Watch with files.
Watch is simply a way to repeat command and watch them execute.
Control C just works.
Control C is your best friend.
When in doubt, Control C.
But you accept the EOF thing.
Sleep for one second.
Give me the list of 10.
Clear.
Watch just simply works.
Very handy.
Keep looking at my IP addresses.
See if anything changes.
A new IP gets created.
Watch is your friend.
It helps in many cases.
So that you don't have to repeat.
Yes, go ahead.
So watch can only show if this changes.
Or it just shows.
Exactly.
It just repeats the command iteratively.
Not like it's waiting for anything to happen.
No, no.
It's just running.
Simply recurring.
It just repeats the command over and over again.
And it doesn't happen.
It just shows you.
It's not recording anything.
Okay.
That's why we just did this one.
ls minus l slash temp.
I just want to see what files are there.
I can just say, hey, I want to keep watching.
This folder.
So it will just keep watching that folder.
It just repeats the command.
That's all.
As always, there might be quite a few number of options.
This one's for you.
Minus d for differences.
You can specify the interval.
You don't have to do it every two seconds.
Okay.
So minus d might be interesting if we said watch minus d date.
Nice, right?
So that's nice.
It's a nice option.
I can just see the differences which are there.
Very handy.
And I think all of this at the end kind of culminates into writing a script that can automate some of your work.
We're not getting into scripting here.
But the point of learning all of these different commands is at the end making your own recipe.
I log in.
I perform some routine tasks.
Maybe a simple script can accelerate that workflow for me.
That's where that kind of comes in.
Just putting it all together.
The life ends with a nice script.
Just talking about creating scripts.
We can start by just creating a simple text file which contains some commands.
I can start like this.
Just creating a simple text file.
Of course there's a whole syntax on it.
But let's do that.
I'm going to create a script.
I was going to do the vi escape dd then I realized this is not vi.
Nothing very special.
Just a bunch of commands right now.
I'll end with some special characters so we understand how these characters could be used.
Alright, here we go.
I save this.
So here I have my script.
How do I make this as a script?
How do I execute it?
Right now it's just a text file.
If I just type this.
Do I have to make it an executable file?
Do I have to make it an executable file?
Whatever.
I just mention its exact location.
I'll wait for Vinny.
I know you were just typing something in.
This is what they find.
What happens if I do this?
Like we did with the binary.
What if I just mention the exact path?
Don't look at that because I need to create a new script.
That file is already done.
So let me just create a quick new script.
And it doesn't do anything special.
All it does is hello.
I am fine with it.
So let me mention the full path.
Here.
Let's mention the full location.
It doesn't like it.
It's saying as a file you are not executable.
It's denied.
When you give it a try, just put the full path of the file.
You can see it was trying as well.
Careful with the file path.
Make sure that that location is correct.
Slash home, slash student, slash new script.
Just careful with what you're writing.
Try again.
It should work.
It will work with an error.
Like what you see in my case.
You're going to get this permission denied.
Sorry, can't execute.
What if I do it the other way around?
I execute by running the shell.
And then I mention the path.
Would this make any difference?
I'm loading a new shell environment, spawning a shell, so to speak.
Hello.
That works.
As you can see, if I manually load a shell, spawn a shell, mention that file, the shell executes, and it runs that script.
The commands you mentioned probably are not there in the file.
Just taking a closer look.
We need to just take a list first.
Let's just do an ls minus l.
Just ls minus l in present.
Let's just see everything we've got.
There is a my script, new file, and there is a new script, new script.
So now one day it cannot find that file.
Maybe you can rename it with mv, new script.
Use the tab, I think it should auto complete.
Is there a new script also?
It is a my script.
And then there is another file that is new script, new script.
Yeah, just backspace.
Put the full file name again, please.
Yes.
Now just write new script.
All right.
That should do the trick.
Thank you.
No worries.
So as you can see, in my case, if I kind of spawn the shell, it works.
But on its own, it doesn't work like an executable.
Let's take a look at this file that I have created.
And what we're going to do is use a very simple trick that many of us know.
chmod is the command used to manipulate file permissions.
I wonder what's happening there.
Let me just take a closer look.
Bash space.
I think inside that file, you have written certain things.
Can you edit that file again, the new script file?
Just do nano.
Because in the script on the third line, all you have written is the name of the script.
We need some commands here.
You can just delete everything here.
And then type some commands.
You can just do uname minus A or hostname or echo something.
Yeah, hostname for good measure.
All right.
That's it.
Save your file.
Okay.
We get it.
We get it.
A couple of commands are good.
All right.
Let's save this file.
Yeah, enter as it is.
Run that again.
Thank you.
You're welcome.
So here I say chmod.
Let's make this executable.
What changes in the permissions?
I get a little x in the permissions of the owner, the group, everybody else.
Anyone and everyone should be able to execute it now.
One way of doing that, either I mention the full path.
If you see last time, that didn't work.
I have made it executable now.
It works now if I mention the full location or just like this because it's in the current location.
Remember dot is your current directory.
Lucky you're trying things.
Already comfortable.
This one I'm comfortable.
I couldn't wait.
What do you think?
I'm putting you in comfort now.
Maybe these are things you're already used to at the moment.
Let's see.
After a dot, give a space.
Cases and cases.
Very important.
How about you?
All well?
The system shut down already?
No, no, no.
Everything is fine.
I think if we run the top command, it might show a different output.
If I run the?
I said if we ran the top command on you, we might see a different output.
System utilization is very high.
I want to tell you a story about the top command.
This is like maybe 15 years ago.
This was for one of the clients.
We were looking at the total CP utilization was very high.
80 percent, 90 percent.
But when we looked at individual applications and we added it together, it was just 10-15 percent.
So this output here of individual process CP utilization did not add up to the total utilization that we were seeing.
And we were just scratching our head.
Saying what's going on?
The system utilization is definitely high.
But we can't see any process which is using that.
And after a bit of low-level D message kernel debugging, what we realized was that one command was creating or one process was creating other processes.
Thousands of processes every second.
And all these processes were instantly dying.
So the system was creating processes and killing them so fast that they were not even showing up in the output on top.
So we didn't see those thousand processes here, but it was adding up to the total.
It was a brilliant low-level debugging of an exercise where the client says something weird is going on in my machine.
Something is eating the utilization.
I just don't know what.
And of course here, if you press H in the top command, there are plenty of things you can see and do.
So it's a brilliant command.
That's a little bit about the final piece, which is just kind of putting it all together and creating potentially certain scripts.
I think that's the natural, I would say, destination.
You learn many commands and then you build scripts.
That kind of tells what to do.
All right, quick one.
Any questions from anyone?
There's a lot we have seen.
So far so good.
Checking glass of notes.
So this is a very good session.
Any unresolved queries or questions, curiosities, things that this session might have made you think, I wonder how that works or I wonder how to do something.
It's just only one thing for me to search a file, to search something that is.
Yeah, I struggle with that.
So if you are talking about finding a file in the file system, we are typically looking at the command find.
It has two core arguments.
One is where to start looking from and what to look for.
If you don't know where to start from, you can always start from the root.
But do keep in mind it can slow things down a little bit, especially on systems which have a large file system.
If you kind of know where it might be, it's always a good idea to filter, limit that scope.
And say, hey, I'm looking for files starting from there.
It's a good start.
Now comes.
Sorry, go ahead.
The type as well.
There's a type option.
So now after this comes, what do you know about that file?
So the first is start looking from there.
And the second is one or more attributes.
Is it a file?
Is it a folder?
Do you know the name, part of the name?
Do you know when it was last modified, last accessed?
All of those parameters.
I can start with the simplest of the things that's saying, hey, I think I know that somewhere in the name is conf.
And then it kind of punches out everything there.
Okay, these are all the files I have found.
So in this case, dash name is literally the name.
If you look at the main page, the manual page for this command, you might see that it supports many expressions.
And you will see some examples here of the expressions.
Some of these are really quite long, but let's try our competency.
Yeah, yeah.
You almost feel like you're reading a book, isn't it?
I understand that's why we end up Googling for it.
Because that might be a bit faster.
Obviously, this is the full system.
And you're like, never mind, I don't need to find it.
Is this the manual for the fine command?
Yes.
Oh, okay.
Like you were saying, you can pretend it's the New Testament.
So last modified less than what we saw right now was dash name.
That's the pattern.
But I can use many of these combinations.
It's in which paths.
What are its permissions?
The classic example is we will look for file, especially if you're doing system hardening or we are auditing a system.
We will look for files with certain kind of permission in the wrong place that could indicate as a compromise of a system.
But you might have your own reasons why you're looking for files.
And this is very useful.
For example, what if I'm only looking for directories?
This is very handy.
I'm only looking for directories.
This is also nice.
All the files owned by a specific user.
The last time the file was used.
Good if you're trying to do a backup or an archive.
Econa likes this one.
Oh, by the way, you can do a lot more with the find command.
Every file which is found, you can execute something on it.
What if I say find all the files owned by this user not access in last 30 days and move them to an archive location?
So fine.
Normally doesn't take an action.
It just but be careful with this one.
But you can not just see the files you can directly take action on.
Maybe I can remove certain files which are less than certain size last access more than five years ago owned by a certain user.
I can just do this dash execute.
Put the command and the parenthesis kind of acts like a placeholder.
Every file which is found, it's like a loop.
So there are other ways to expand on it.
That means you and if you don't want it to execute without asking you, you can say dash.
OK, ask me one by one.
If you trust your command, close your eyes.
No need for dash.
OK, go.
You find thousand files that match this fine.
Execute something on them.
Copy them, move them, remove them, whatever.
Please be careful with these.
The potential for messing things up is high.
But the wonderful things you discover if you read the man page.
Big man page, right?
It's just one.
Book.
Finally got it.
Hopefully that answers the query.
Around the find and how to find what you're looking for.
So look for those expressions.
A time, M time, dash user.
All of that should do it.
Any other questions from anyone else?
How to get something specific done or any curiosity or anything?
Yes, there's another, I don't know if I'm mistaken, there's a command called locate.
That's great.
The same as.
Find or it's just me.
Depends on the distribution that you're working on as well.
Oh, OK.
So I think not every distribution will have looking.
Let me just check right now.
Because the idea is that we might things might be a little bit faster if there is like an index of sort.
Let me just check which distributions supported.
Because it may not be for.
Every distro as well.
I think I mean, as you can see here as well.
It's not built in as a package.
You'd have to install that tool again if you don't have administrative rights, you may struggle to do that.
But if I'm not wrong, I could be wrong.
I believe it's something that creates kind of an index.
OK, so it runs in the background like every day.
I think once 24 hours and then it kind of builds an index.
So that is a lot faster.
Find command is literally going through the entire file system tree.
So in larger file systems, you could be sitting there for a very long time.
And other tools like locate what they do is they kind of offload this a little bit by automatically building indexes like indexing service in Windows.
Making it a lot faster because it maintains a database of what's where with the metadata.
OK, so that's the reason we don't see it here.
It might be there on the systems that you're working on.
So find is literally sifting through the file system.
Locate builds an index.
There are similar packages and cost different distributions.
Hopefully that helps.
There is also something I just saw somewhere called iNodes.
We saw when we did the hard links.
OK, so that was iNodes.
I think it's iNodes.
Here, here, this is the iNode number.
The door and the room.
Oh, iNode is the room number.
All of this sounds like mumbo jumbo, right?
When the context is not very clear.
And now you're like, ah, so that's what it is.
It's just the identifier of the actual result.
So what did you see when I create that link with the red file and the blue file and the pink file that they were all pointing to the same iNode?
Yes, yes, yes.
Pointing to the same resource.
Great.
Anything else?
Go ahead.
Any questions from anyone else?
E2, Winning.
Go on.
Ivan.
Thank you.
Thank Kurt, thanks.
Yeah, I'm also good at it.
E2, that I am good really sounded like the system shutting down.
George, better George.
Sounds like a dialogue.
I like the analogy of network people saying it sounds like a dialogue connection.
I remember back in the day when we were hooking up to service provider networks through slip before PPP.
You had to type in your own IP address.
Once you dialed in, it's quite strange.
You dial into the ISP and the ISP is like, so what's your IP address?
So this is before PPP.
And I remember like, wow, the IP comes from the provider.
It's amazing.
Back in the day like, hey, I've connected.
Quick, give me the IP address that we have.
And then you had to type in.
Yeah, brilliant.
All right.
That's pretty much is the end.
As I said, small document with some of these and the deck.
I'll just make sure it has that on the cloud storage.
You can always have that as a reference.
Hopefully now again with the mission that we had to get more comfortable with the command line.
Hopefully we've made progress there.
How do you use the no-hang up?
The idea is that if you're running.
So when you say no hang up, typically the idea is if you are remotely hooked up to a system,
Telnet, SSH, whatever, we don't want the process to die if the shell dies.
And that kind of makes sense.
If I log out, then my login shell is gone.
And the process that I have started is often.
Typically you kind of do this at the end of the command.
What that literally does is it changes the parent process of that process.
And the parent of that process is like maybe the I net demon, basically like the core of the system.
So now it no longer matters if this shell that I am in dies.
Who cares?
My child process will survive.
So typically you do this if you're doing patching or some other work.
I remember sitting in front of a system for six hours, making sure the terminal doesn't close till somebody showed me that.
But GP, now there's the screen command.
Yeah, there are.
Again, see, as you go from the archaic historic Unix environment, the more you go towards the Linux, what has fundamentally changed is all of this.
And now for the last 10 years, Unix is borrowing from Linux.
They are saying, you know what?
People want these capabilities and they want these features.
And then some Unix, if not all, they have started to adopt.
Look, the fact is, in the enterprise world, Unix adoption is the Linux.
No, no, no.
It's just I mean, we can't list every distro out there.
There are thousands of them now.
I think new ones pop up every day and then everybody's everyone has their own favorite ones and they swear by it.
So I have personally worked.
I'm not going to say on all, but everything which is on the enterprise side.
I've worked on your suzes, your Red Hat and everything else.
HP, UX, your Solaris, Go, all different systems.
In the Linux world, yes, new distros come up all the time.
You pick the one that works for you.
And frankly, it's more of an enterprise decision.
Yeah.
And then the reality is comfort of sysadmins is the last consideration, if ever, in choosing a platform.
It's the overall productivity, stability, how it matches the ecosystem that you currently have.
And in the long run, what the direction of infrastructure, the long term goals of the enterprise kind of goes in there.
So no right, no wrong is what works.
Obviously, everyone has their own favorite.
I like this one.
I like that.
So that's your no hang up.
All right.
Anything else from anyone?
Again, questions, doubts, thoughts?
Nothing else to say.
You're welcome.
All right.
Anything else from anyone before we wind up?
No, no.
All good on my side.
I appreciate that.
Ito, thanks, guys.
Thanks for being here.
Spending a day with me on Linux fundamentals.
Hopefully, you were a bit more comfortable on the terminal the next time you are there and more adventurous as well.
Trying new things out.
Thank you.
Thanks.
Thank you.
Yeah, it's pretty close.
All right.
See you guys.
Take care.
Okay.
See you.
See you sometime.
Take care.
See you in my room.
I don't even want to have a conversation.
I don't want to have a conversation with dirty people.
Run away, run away, run away.
Have you seen?
Hello.
Bye, my friend.
What happened?
I'm calling someone.
I'm calling someone.
I'm calling someone.
Haseed.
Where is he?
The number of people wasting time is just crazy on the phone.
Thank God I don't have WhatsApp.
Imagine the number of people who get your number.
What are you wearing on your skirt?
And what's this?
He might be out there in the marriage.
Haseed is busy with his work.
He won't pick up the phone.
I'm going to do some research for tomorrow.
It's difficult.
It's difficult.
It's difficult.
It's difficult.
It's difficult.
Please get up.
You haven't showered go.
I'm trying to with my best but I don't know how I'm going to get up.
I just want you to shower.
Don't even talk.
You want to say hello to our neighbor?                

on 2025-02-19