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Hello everyone.

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In this demo, I'm going to show you some examples of bash scripting.

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Let's start with the first example, the user input.

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So I'm going to start, as you can see over here.

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Here are some examples.

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So I'm going to start with the first example here.

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The user input, the strings that is So strings go.

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Here we see what is the script over here?

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As we can see here, this is the shebang.

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The first line and here is the comment, I think nothing new over here.

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So this is says that this is the this script shows your first name.

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Also.

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Maybe you can type here also your first name and last name.

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Perfect.

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Next, as we can see over here, echo the echo command.

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We're going to all in this line just we are going to type or we're going to show just this message.

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Hello, may I know your first name?

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Then we can see here.

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This is the command read.

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So this command is going the read command is going to transfer the control from the running script,

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which is the script.

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To the user in order.

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Why?

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To let the user to type the first name and the last name, then store whatever the user enters.

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So we're going to store.

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For example, if the user entered, the first name is John, so he's going to store.

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Store or save the the name over here and this variable.

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A first name.

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And there is also a second message over here.

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We asking the user to enter the last name and we're going to save whatever the user is going to enter

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and the last name variable.

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And here we're going to show a message after that.

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So thank you.

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Then as we can see, this is the dollar sign.

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Why we're using the dollar sign before the variables, because we would like to show what the user entered.

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So we're going to show the value.

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We're not going to show the name first name if we're not going to put the dollar sign.

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So the system is going to show first name and last name.

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So the reason we put the dollar sign, because we would like to print the value of the variable.

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Perfect.

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So far, so good.

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Now let's run this.

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So control, so shift x colon X, then the bank or the exclamation mark hit Enter.

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Now I'm going to run this script.

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Strings.

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That is hit enter.

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So as you can see over here.

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Hello.

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May I know your first name?

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Say, John.

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Then hit enter will ask me the second question.

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Say your last name.

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You know, just I'm going to just type uppercase L hit enter.

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As we can see here, this is the last message.

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Thank you, John.

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L So far, so good.

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Perfect.

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Let's move on right now to the second example.

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So the second example that I would like to show you is the sum.

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So sum that is H hit enter.

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So as we can hear, this is the shebang line.

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This is the comment.

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So this script shows the sum of the three numbers.

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So as we can see here, here's the parentheses because we would like to do some between three numbers

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and we put so sum here is the variable then equal 20 plus 30 plus 40, and we put all of them inside

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double parentheses, as you can see here, two parentheses at the beginning and at the end, two parentheses.

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Then here we're going to show a message echo.

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The numbers are 20 plus, 30 plus 40.

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And the second or the last line here or the third line.

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The last line here is the result is and as I mentioned in the previous script, we need to.

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Type the dollar sign and then the name of the variable.

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So this is the variable here.

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So we need to do that in order to show what is the value of that variable.

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Perfect.

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Just run the script.

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So some that search hit enter.

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As we can see here, the numbers are 20 plus, 30 plus 40.

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And here is the return.

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So here is the sum of these three numbers.

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You can do the same thing.

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But as I mentioned before, since I do cat home slash John and slash dash bash says hit enter.

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As I said that because I added this line over here.

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This is the line and this file is the configuration file.

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So I don't need to type the dot slash or the bash before the name of the script file.

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Okay.

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Now let's move on.

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Let's move on to the third example.

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So the third example here is the length.

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So the length that is H So what is the purpose of this?

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This is the shebang line.

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So here I would like to show a message to the user.

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Could you please type your name and your age?

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And we have the read command.

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And as I mentioned before, the read command is going to transfer the control from the running script

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to the user.

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If you guys remember when we showed that message and we asked the user to enter the value, So so the

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so is going to lead the user to type the the name, then the age, then we're going to store whatever

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the user entered in this variable in the length variable.

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Then what we're going to do here, we see the message over here is the last night.

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So the length of this string.

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So the purpose of this script, I would like to show what is the length of the variable that the user

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is going to type.

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And I know it's kind new for you guys.

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So here is the dollar sign, the reason of the dollar sign because we would like to get the value.

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Then we have here what we have.

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We have the braces, then hash length, then we close the braces.

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So we it's really important that we know the structure because this is the syntax structure of the bash

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scripting.

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So in order to get a good outcome, we need to know the structure.

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So dollar.

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Then we open the parenthesis and we close it.

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Then inside that hash length, let's run the script.

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So length that is h So what's your name?

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My name is John.

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And say I'll say here, my name is John and for example, not 50, 30 years old, hit enter.

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As we can see over here, this is the message.

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The length of this string is 37.

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So this is the length and also is going to consider the spaces.

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So from here to here, if you're going to count them, they are 37.

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Okay, So now let's move on.

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There is a file also I would like to show you before I'm going to explain the fourth example, the if

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else.

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Okay.

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So cat slash home slash and I save that file under the directory.

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That is examples and operators hit enter.

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So this is the syntax that we're going to use in the bash scripting.

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So here is the samples.

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We're going to use those, the syntax.

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So the dash EQ, it means that equal, equal.

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So it means equal if we'd like to compare between values, for example, if I would like to compare

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between two values, the value one it's two and value three.

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So value one is two and value two is three.

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Are they equal?

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Not they are not equal.

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And this is the another syntax that we're going to use in the in this, the bash script.

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So dash and E, it means not equal and here is dash get greater than dash G so it's greater than or

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equal and dash lt is less than or dash la so is less than or equal.

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Okay, now let's run the script.

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So the script is f ls f dash ls h enter.

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So as we can see over here.

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So the purpose of this script, we would like to ask the user, so to ask the user a question, what

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is the root user uid?

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The Uid, so you know that every user has a Uid.

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Then this is the read command.

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So it's going to transfer.

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As I mentioned before, is going to transfer the controller from the running machine running script

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to the user in order to type.

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For example, type whatever string or ID.

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And here is a comment said the Uid of root user is zero and here we have the.

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So as I mentioned before, we need to know the structure in order to understand any programming language

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or even the bash scripting, you need to know the structure.

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So for if else is a condition.

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So we type if.

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Then else.

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Then we close the F, so F, then we close this f.

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So between here, as you can see over here, this is the.

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The brackets.

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So between the brackets, we need to leave spaces at the beginning and the end.

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And here the value is zero.

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So this one is what?

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Equal.

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So if this value equal to this value.

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So the dollar sign.

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And we need also to put in between the quotation mark because we're going to compare these two values.

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So I'm going to compare this value with this value.

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If they are equal.

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So if the first value is equal to the second value, then.

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Print this message.

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If this value is not equal to this value, then we're going to skip this.

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We're not going to do anything.

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So we're not going to print this line.

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We're going to go to the else.

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So if this is true, then we're going to print this one.

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If this is false, this line is false, then we're going to print whatever is under the else.

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So if you are not the system administrator, let's run this script.

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So if else that is h hit enter.

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So what is the root user uid if I hit zero, you are the system administrator.

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Let me show you the content of this script.

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Shebang line doesn't matter here.

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So this is a question.

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Perfect.

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We give the user and we lead the user to enter the value we saved zero in this variable.

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So the value of ID is zero.

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Then it's a comma.

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Here is the comment.

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It doesn't matter.

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So we're going to take.

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So if this value is zero, it's already zero equal to this value, which here is the value here.

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So the dollar sign ID, then print this one and this is what the outcome of the script.

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You are the system administrator and we get this message if this one is not true.

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False.

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We're going to print this message.

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So far, so good.

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Perfect.

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Now let's move on to the fifth example.

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The while loop.

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So for a while loop.

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That is it.

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So this is a loop.

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If you hear about loop, it means that it's going to is like there is iteration that is going to go

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over values like more than once.

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Okay.

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Let me explain.

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What what do you mean by that?

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So here is the this script prints the numbers from 1 to 10.

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So this is the main objective of this script.

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And this is another comment here.

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This is the initial value, the initial value for the X, We assign a value to this variable.

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So the variable is X, So x equal one, it means that I'm going to assign number one, the value to

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this variable.

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Next here is a comment.

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So this is the while loop.

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So the while loop here we have the while do then done.

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So if the while if this line is true, then do this line.

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It means you go inside and print this line.

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Then if it gets notice here we have the parentheses x and c x plus plus and between double parentheses

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y we need what does it mean?

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That x plus plus it means that is going to increase the value.

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So the initial value, it's one.

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So we're going to so we're going to run the script.

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So it's going to run line by line.

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We'll ignore.

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So this is the shebang.

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Ignore this line, ignore this line.

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Then we'll assign one to the X, then ignore this line.

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Then we'll go to the Y line.

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And we have here we have the brackets.

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So the brackets here, as I said, that you have to leave a space at the beginning and end.

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And then as I said before, we need to use the dollar sign in order to get the value.

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We don't want to use the variable.

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We don't I don't need the x Y.

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I need to I need to compare X to ten.

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I need to compare the value of x, which is 1 to 10.

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So he said if one is less.

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Then ten.

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Then do this line.

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So the number is and we're going to print the number.

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So here is one.

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One is less than ten.

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Good.

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True.

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So the number is one.

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Then we're going to increase it.

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So we're going to go back again here to the while line here.

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So this time.

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So after we increase the number to two, two is less than ten.

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Yep.

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Good.

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Then we're going to increase.

250
00:15:34,850 --> 00:15:39,590
We're going to print two, then increase the number 2 to 3 and go up again.

251
00:15:39,830 --> 00:15:45,800
And here is three less perfect print three, then increase it to four.

252
00:15:45,800 --> 00:15:53,750
We're going to do it till we're going to reach what, two number ten.

253
00:15:54,080 --> 00:15:59,510
So if we're going to let me run the script so we can get an idea about it.

254
00:15:59,510 --> 00:15:59,830
Okay.

255
00:15:59,840 --> 00:16:06,980
While loop, while dash loop that is which enter as we can see.

256
00:16:07,010 --> 00:16:07,250
Three.

257
00:16:07,250 --> 00:16:10,070
So cat while loop.

258
00:16:13,680 --> 00:16:14,190
Ginger.

259
00:16:14,640 --> 00:16:20,400
So the initial value here, we compare this 1 to 10, perfect is true.

260
00:16:20,400 --> 00:16:21,620
So we're going to print this one.

261
00:16:21,630 --> 00:16:28,230
So the number is one, then we increase two, two two is less perfect.

262
00:16:28,230 --> 00:16:30,930
We're going to print two, then increase it to three.

263
00:16:30,930 --> 00:16:32,370
We're going to do it till ten.

264
00:16:32,490 --> 00:16:39,480
Once we're going to increase it to 11, the last value here, we're going to go over here and is it

265
00:16:39,480 --> 00:16:41,100
11 less than ten?

266
00:16:41,130 --> 00:16:42,780
No, false.

267
00:16:42,780 --> 00:16:47,970
So we will jump from here to done.

268
00:16:48,360 --> 00:16:49,890
We're not going to do.

269
00:16:51,040 --> 00:16:55,660
This two lines anymore because we 11 is less than ten.

270
00:16:56,650 --> 00:16:57,310
Perfect.

271
00:16:57,310 --> 00:16:58,140
So far, so good.

272
00:16:58,150 --> 00:17:00,640
Okay, let's do the sixth example.

273
00:17:02,620 --> 00:17:05,829
And this example, it's the for loop.

274
00:17:06,369 --> 00:17:08,380
So it's the same concept.

275
00:17:11,140 --> 00:17:12,430
It's a different structure.

276
00:17:13,000 --> 00:17:14,770
Both of them are loops.

277
00:17:15,130 --> 00:17:19,300
The while has different syntax and therefore has different syntax.

278
00:17:19,300 --> 00:17:23,980
So here is the same thing printing from 1 to 10 for loop.

279
00:17:24,010 --> 00:17:26,589
So here, let's see the syntax of the for loop.

280
00:17:26,589 --> 00:17:29,080
So we have for do then done.

281
00:17:30,230 --> 00:17:39,620
So if let's go for here let's go to to this line for then we have the double parenthesis.

282
00:17:40,410 --> 00:17:41,730
We need to put the condition.

283
00:17:41,730 --> 00:17:48,330
So the difference here, if you guys notice in the while we assign the initial value before the Y.

284
00:17:49,580 --> 00:17:50,330
Command.

285
00:17:50,600 --> 00:17:58,010
Although I lie here for the four, we have three things we need to do it inside the double parenthesis.

286
00:17:58,130 --> 00:18:04,070
We have the initial value, then semicolon, then we have the condition, then semicolon.

287
00:18:04,070 --> 00:18:07,670
Then we have the increment that we're going to increase the number.

288
00:18:07,670 --> 00:18:11,420
So the initial value for x is one, then semicolon.

289
00:18:11,870 --> 00:18:13,790
Then we're going to compare X.

290
00:18:13,910 --> 00:18:15,500
Is it equal?

291
00:18:16,010 --> 00:18:21,410
Is less or equal than ten, then semicolon, then we increase.

292
00:18:21,680 --> 00:18:22,520
Then here.

293
00:18:22,520 --> 00:18:26,510
If it's true, if this line is true, then we print the number last.

294
00:18:26,810 --> 00:18:28,340
Let's do a demo here.

295
00:18:28,850 --> 00:18:30,500
We're going to run the script.

296
00:18:31,820 --> 00:18:36,560
Hit enter cat for loop hit enter here.

297
00:18:36,860 --> 00:18:40,580
So these three lines, we just ignored them.

298
00:18:40,580 --> 00:18:43,070
This is the shebang line.

299
00:18:43,070 --> 00:18:43,790
Comment.

300
00:18:43,790 --> 00:18:44,540
Comment.

301
00:18:44,540 --> 00:18:46,850
So here is the initial value one.

302
00:18:47,710 --> 00:18:50,260
X, It's one here.

303
00:18:50,260 --> 00:18:54,790
The value less than or less than or equal to ten.

304
00:18:55,540 --> 00:18:56,290
True.

305
00:18:57,010 --> 00:19:04,720
Then we're going to increase the value and then print this message.

306
00:19:04,720 --> 00:19:07,480
The number is one and we're going to do that.

307
00:19:07,720 --> 00:19:09,250
We're going to print the last value.

308
00:19:09,250 --> 00:19:11,290
So we're going to reach here to 11.

309
00:19:13,030 --> 00:19:16,210
So here is so when are you going to be over here?

310
00:19:16,210 --> 00:19:18,340
If it's here, the condition is false.

311
00:19:18,340 --> 00:19:19,690
It will jump.

312
00:19:19,780 --> 00:19:26,740
It's not going to look to these two commands will jump to the to the last line, to the done.

313
00:19:28,420 --> 00:19:29,500
So far, so good.

314
00:19:29,500 --> 00:19:32,710
Let's now move to the last example.

315
00:19:32,710 --> 00:19:37,300
The last example is the array example array.

316
00:19:37,960 --> 00:19:39,790
So the arrays, that is each.

317
00:19:39,940 --> 00:19:42,910
So the array is like a list.

318
00:19:42,910 --> 00:19:45,040
You have a list of items.

319
00:19:45,280 --> 00:19:52,180
And as we can see over here, here is the name of the array list equal.

320
00:19:52,450 --> 00:19:54,610
Then we have the parenthesis.

321
00:19:54,610 --> 00:20:01,510
We open parentheses, just we have single parenthesis beginning and at the end then here is the items

322
00:20:01,510 --> 00:20:03,340
inside this array.

323
00:20:03,340 --> 00:20:11,140
So and we need to type the items or the value of each.

324
00:20:12,560 --> 00:20:14,570
Uh, index.

325
00:20:14,600 --> 00:20:16,700
I will explain what I mean by the index.

326
00:20:17,360 --> 00:20:25,250
The index is like, uh, you can compare them like a storage.

327
00:20:25,790 --> 00:20:31,400
So the first, uh, storage is zero.

328
00:20:31,850 --> 00:20:35,390
This is the index or the number of that.

329
00:20:35,390 --> 00:20:37,130
The first storage is zero.

330
00:20:37,160 --> 00:20:38,960
This is the index zero.

331
00:20:38,990 --> 00:20:44,630
This is index one and this is index two and this is index three.

332
00:20:44,810 --> 00:20:48,110
So for the array we start.

333
00:20:50,040 --> 00:20:55,530
The numbers when we start the index from zero.

334
00:20:56,010 --> 00:20:57,360
Then we go to one.

335
00:20:57,390 --> 00:20:59,580
Then we go to two, then three.

336
00:20:59,610 --> 00:21:01,620
So this is the index value.

337
00:21:01,800 --> 00:21:08,790
So if I will say what is the index value of the index value on list array?

338
00:21:09,360 --> 00:21:15,660
The index zero, let's say the index zero of the list array is sent to us.

339
00:21:16,050 --> 00:21:19,170
What the index value.

340
00:21:19,830 --> 00:21:23,400
What is the value of index two?

341
00:21:23,430 --> 00:21:26,610
So here is 012.

342
00:21:26,640 --> 00:21:27,480
It's fedora.

343
00:21:28,500 --> 00:21:31,410
And what is the index value of?

344
00:21:31,410 --> 00:21:33,570
What is the value of index three?

345
00:21:33,600 --> 00:21:34,470
It's upon two.

346
00:21:35,310 --> 00:21:37,020
And so this is the array.

347
00:21:37,380 --> 00:21:38,760
And we have the for loop.

348
00:21:38,760 --> 00:21:42,750
I already explained the for loop, but there is something interesting over here.

349
00:21:42,750 --> 00:21:48,030
We have the echo message and here the the dollar.

350
00:21:48,750 --> 00:21:51,310
Then the value, the variable x.

351
00:21:51,310 --> 00:21:57,310
It means that we would like to print the value of the variable x is.

352
00:21:58,090 --> 00:22:02,380
And here is the the interesting part.

353
00:22:02,650 --> 00:22:04,040
So here, why?

354
00:22:04,040 --> 00:22:12,610
Why I wrote it like that way because I would like to print the items inside the array.

355
00:22:12,640 --> 00:22:13,750
The list array.

356
00:22:14,080 --> 00:22:16,320
So as we can see, here is the dollar sign.

357
00:22:16,330 --> 00:22:20,530
So we use the dollar sign, then the braces.

358
00:22:20,530 --> 00:22:28,180
So we open one press here at the beginning and then as last press at at the end, then the name of the

359
00:22:28,180 --> 00:22:29,500
array, which is list.

360
00:22:29,530 --> 00:22:31,240
Then between.

361
00:22:33,420 --> 00:22:43,320
The sea here between the brackets, we put the value of the X.

362
00:22:43,320 --> 00:22:46,680
So all of these, because we are using the dollar sign at the beginning.

363
00:22:46,680 --> 00:22:48,390
We don't have to put the dollar sign here.

364
00:22:48,390 --> 00:22:58,740
So the dollar sign that's outside the the, the, the braces, then the name of the array, then brackets,

365
00:22:58,740 --> 00:23:03,060
then we're going to print the value of X.

366
00:23:03,360 --> 00:23:06,990
Let's run this script.

367
00:23:08,250 --> 00:23:13,800
So arrays enter, as we can see over here, let's say cat arrays.

368
00:23:14,490 --> 00:23:17,670
So here is the value of index zero.

369
00:23:18,210 --> 00:23:26,310
So this is index zero is sent to us and the value of index one is read had the value of index two is

370
00:23:26,310 --> 00:23:31,980
fedora and the value of X of index three, it's up one, two.

371
00:23:32,190 --> 00:23:33,880
And how did we bring that?

372
00:23:33,910 --> 00:23:35,620
We use the for loop.

373
00:23:36,220 --> 00:23:37,900
So this is the condition here.

374
00:23:38,290 --> 00:23:39,640
Zero is zero.

375
00:23:39,640 --> 00:23:40,900
Less than three.

376
00:23:41,500 --> 00:23:42,070
Yes.

377
00:23:42,070 --> 00:23:42,730
True.

378
00:23:43,000 --> 00:23:46,360
Then we're going to print this line and increase.

379
00:23:46,360 --> 00:23:48,430
Also increase the value.

380
00:23:48,580 --> 00:23:53,560
So we're going to print zero here as the first value.

381
00:23:53,560 --> 00:24:01,120
Then we're going to print the value of index zero and we're going to do that till we're going to reach

382
00:24:01,120 --> 00:24:04,930
two for four.

383
00:24:04,960 --> 00:24:07,120
Is it for less than or equal three?

384
00:24:07,120 --> 00:24:08,350
No, that's false.

385
00:24:09,130 --> 00:24:10,240
This line is false.

386
00:24:10,240 --> 00:24:13,390
Then we're going to jump to the end.

387
00:24:15,100 --> 00:24:17,680
So that's conclude our session.

388
00:24:17,680 --> 00:24:19,420
Thank you very much.