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- So we've talked about working with Linux

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and logging in and user
accounts a little bit.

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It's time to get to know some commands.

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So I have put together some
of the most useful commands.

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These are the commands
that you are going to work

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with a lot, especially
if you're a starter.

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It starts with whoami,
giving you your login name

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in case you're confused about it.

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ls for listing files, ip a,
which was print your IP address.

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Cat, very convenient to show text cells,

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passwd for for setting your password,

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touch, for verifying writability
of specific directories

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and pwd for printing working directories.

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Let me show you all of these.

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All right.

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Let me start with whoami.

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I am user student and
do we have any options?

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I would always advise

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if you're starting to learn
new commands, type command

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minus minus help just for the sake

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of it to find out if there are any options

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and it appears for whoami, there are not

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then let's have a look at
ls, ls is listing files

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listing files in the current directory.

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And it has a lot of options.

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ls minus minus help is showing
you all of these options.

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It has so many options

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that it doesn't even fit in one alphabet.

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Do you see that we have a lowercase x

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and we have an uppercase x, for instance.

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Now, as I said, ls has a lot of options.

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There's two of them that stand out,

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ls minus a is showing hidden files

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which are files that have
a name starting with adult.

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And then there is ls
minus l the long listing

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and you know what?

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You can combine them as
well and make it ls minus la

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which shows a long
listing of hidden files.

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In the long listing, you can
see additional information

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about your files, like permissions
and owners and creation

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date and time, which is all very useful.

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We'll talk about it later
in much more detail.

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The purpose now is just to
get you up and running as fast

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as possible.

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Now we have ip a.

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ip a is showing your IP
address and what you should be

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looking for is your second interface.

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The first one is l0. l0 is looping.

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That's your internal IP stack,
always set to 127.0.0.1.

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Look at the second one, ens33.

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And it's showing me that I
haved IP address 192.168.29.141.

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And that can be convenient.

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If I want to make my
system reachable, then

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another one is get, get
works on text files.

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And you know what?

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On Linux, almost everything
is stored as a text file.

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And if you want to read
the contents of a text file

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you use get for example, get

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on etc hosts, which is
a file that you can use

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for name resolution.

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That is the name belonging
to a specific IP address.

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As you can see, not much
interesting going on here.

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Right, then there is passwd.

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passwd allows you to change
your current password.

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If you wanna do that

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you need to enter your
current password first.

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That's your protection, just to make sure

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that nobody is changing your
password as a joke or so.

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And what do I get?

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Oh, no bad password.

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Password is the same as the old one.

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Yes, it is right. And that is

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because I did not really want
to change my password anyway.

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And you know what, if you have
root privileges, then passwd

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minus minus help is showing
so many interesting options

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but as you can see a root only

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so that means that you
need to run them with sudo.

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We will talk about that later.

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Let me type touch, touch hello

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What is touch hello doing?

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That will create an empty
file with the name hello.

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Why is it useful?

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Well, that is useful

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because in a Linux system,
as an ordinary user

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you only have a limited write permissions.

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And if you want to verify

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that you can actually write
to a specific location.

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Well, touch is an awesome command.

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In fact, this thing that
I'm doing right here

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touch on hello to, to create an empty file

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with the name hello?

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Isn't even the real reason
why touch was created.

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Let me do a touch hello again.

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And now let me do the
ls minus l hello again.

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And do you see the difference?

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The difference is in the timestamp.

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If you use touch

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then you are going to
change the timestamp on

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on the file to the moment
when you ran touch.

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And that is functionality
that can be useful

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in backup environments, but honestly

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nobody uses touch that way.

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People are using touch
to verify writability.

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And that's something that you
are going to do a lot as well.

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Finally, pwd

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for print working directory,
that is showing you the name

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of the directory that you
currently are in and in Linux.

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And we will talk about
these directories a lot.

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In Linux you won't always
see where you are in.

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If I type cd slash var
slash log for instance,

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I only see log.

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And if I want to see
the complete name, well

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pwd and oh, now, now

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that we are talking about cd
for change directory anyway,

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if you use cd followed by nothing

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it'll always bring you back
to your home directory.

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And do you see that you
can easily recognize

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the home directory by the tilde?

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All right.

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I think that's all, that's
eight commands so far.

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Let me throw in one
more, which is history.

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History is a very convenient command.

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It allows you to verify all
that you have just done.

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So here's my command history.

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That's all for this video.

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Let's move on to the next topic.