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OK, now let's start with environment variables.

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Now, when you open a terminal window and you bash process, which has its own environment, variables

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is initialized and these variables are form of global storage for various settings inherited by any

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application that are run during that terminal session.

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So opening the terminal here?

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OK, I want to increase the font size a little bit.

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OK.

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It's clear the screen now here we have the first environment variable, which called the best, and

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we already saw it.

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So I will use the eco command and what there are saying and the name of the variable.

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And this is not just the variable, it is environment variable, which means it is for the system.

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So he called Beth here.

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It will start showing us the bath where clinics will start looking to check for comments.

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We have other environment variables like the user so equal user.

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Here it will show us what is the current user, which is Kelly.

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And by the way, we can see that from here, which is Kelly.

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We can see the working directory, so by typing the BWT, we know that we are inside home canning now

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we can use Eco Star or Dollar Sign BW Rd, it would show us Home Kelly as well.

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OK?

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Also, we can use another environment variable, which is home.

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This is the home directory for the current user, which is home.

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As we saw, OK, by the way, we are inside the tilde.

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That's why bwt, it will show us the same value.

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So if I go, for example, to desktop.

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OK, now if I type B, it will print the working day to read Please don't get confused, OK, be ready

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or equal that p wd it would show us home Kelly Desktop, which is where is the current directory or

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print working directly or the current directory?

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Which is here.

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All right.

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But eco home, it will show us the home directory for the current user, which is kidding.

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Now what if we want to create a new variable inside the bash?

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So first, let's clean the screen.

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I want to declare this variable VAR one equal.

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For example, one six eight.

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For example, it's split inside that Google dot com.

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OK, Google dot com.

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All right.

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So if I type equal dollars sign VAR one, it will show us Google dot com.

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But if I type, or if I open a new terminal or control shifting and and if I type eco VAR one again.

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OK.

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It would show us nothing.

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Why?

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Because we open a new chairman session, so this variable is inside the current process.

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So again, if I type Bash Command and Bash Command here is to open a new bash inside this process,

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so it will be considered as a process if I type eco VAR one.

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It will show us nothing.

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So how to make this very available for all the sub processes?

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Well, first this button the exit command.

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This is to exit from the current situation or by typing control.

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OK, so at the exit.

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Now, if I type Eq. again, you can see that it is Google Dot com.

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No, I will use command called export.

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So this export VAR one equal.

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YouTube dot com, for example.

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If I type equal born this time, it would be YouTube dot com.

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Now if I open a new bash, OK?

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Busted ring or a process?

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If I thought it could bar one, it will be here, which is YouTube dot com.

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OK, so far, so good.

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Now, if I type control D or exit clear the screen eco bar one.

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Yeah, YouTube dot com is still here, so we will use export command for such things to have this variable

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for all the sub processes.

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Alright, now what is the use of the variable?

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Of course, we can use it in scripting out of sync.

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So for example, Bing, then I sign over one.

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This will start bringing YouTube dot com.

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But again, don't do this on life targets by the way of being will not do anything harmful.

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But please don't do any scanning or any any sense, whatever on life targets, because you may get in

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trouble.

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Now we have special variables.

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First is the screen.

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The first one, which is equal, though don't sign dollar sign.

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So here it will bring us the current process ID or ID.

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So the current ID.

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Opted for this bash, terming that process is like this, no, OK, one thousand one hundred five.

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So to make sure open a new bash, no type equal, they're not saying they're not sane.

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You can see that.

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Oh, it is different, which means this is another bash process as a separate process inside this batch

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process.

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And it would show us that pretty well.

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So we have the equal.

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So first, the split from dispatch, clear screen equal, then up sign and question mark.

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So this to tell us what is the status of the last running comment so that it's zero, which means it

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is run successfully?

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Other than that, it will be considered filled.

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So for example, let's put this command.

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This is not the command.

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This is an error.

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As you can see, command not found.

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If I type equal the last question mark, it would be one hundred twenty seven, which means there was

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an error.

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OK, but if I run again, if I run it again, what is the last command which is equal that I sign?

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So this will be zero?

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All right, good.

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So far, so good.

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So this will give us the status of the last running command.

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If it is zero, which means successful, other than that, it will be considered failed.

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Now to see all the variables.

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So for example, we have that VAR one.

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Remember or VAR one here.

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So to see all the environmental variables or the variables run the command and so on, run it like that.

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And you can see that here is all of the commands are here or the variables.

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I mean.

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OK.

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So you can see that, yeah, VAR one it is here.

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VAR one equal YouTube dot com.

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So all of the environment variable that are here inside that the bash process will be here.

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OK, now if I quit again from it, from the process, if I run it again, this increase the font size

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equal VAR one you can see, Oh, it is not here.

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OK.

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If I type in the same thing.

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Warren is not here.

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As you can see, why is that?

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We will talk about this later on.

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There is something called the bash RC, OK, here.

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So I was on this command at the cat that bash our see here we can.

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But whatever variables, then it would be exported each time we run the bash program or Tanami.

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Don't worry, we will talk about this in detail later on.

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For now, keep that in your mind.