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Let's show string comparison on some example grade file string age on first line start with shopping.

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Ben Besh now we can create two string variables to first string variable sign.

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Are you whole body

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and to string to sign.

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Hello body but with capital H.

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Now we can compare both of them to see if they are equal or not into square brackets put dollar sign

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single on equal sign dollar sign stating to.

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And of course don't forget on double quotation marks next to variables.

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So if that condition is true the print message equal if not visual print not equal

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savefile

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ground equal permission

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and running

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b c not equal which is scored because second string has capital H in the beginning.

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I will go back to scrape and replace capital H with lowercase.

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Now it should say equal so save the script.

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Yeah and it does great.

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Let's make some more changes.

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Firstly Warbeck.

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Keep it up.

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Age instinct to

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and for the if statement change singles for a bracket to double square brackets.

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And in that case we don't need to use double quotation marks

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now say the script and the right not equal grade.

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It is working but to be sure what's changed back.

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Capital H to lowercase

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and now it should be in equal

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and it does now it is up to VUDU really use for string comparison.

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You can use single square brackets with quotation marks next to variables or just to use double square

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brackets.

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As I said previously mostly Are you single square brackets due to the fact that double brackets are

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a kind of specific to beshe only and other shows don't use them.

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Let's open the script again and I will show you how spaces can be dangerous.

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But firstly change back from double square brackets to single one.

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Now I remove the space next to the left bracket.

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You can now safe descript and and we see the error message on line 6 but what's more descriptive Vasan

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exited but it continued and a printed message not equal.

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Even if our strings are completely equal here you see what simple space can do.

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Because on every line vase at or it was a line number six.

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It was for beshe false statement.

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So the script continued to our statement that it is.

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But in THINK OF NOT equal let's fix that space at our next door.

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Well I've described a bracket

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and do another one.

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Now we can remove space next to equal sign.

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When running we still got error message and printed message not equal.

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So let's correct it.

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And we see that now the message is equal.

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Great.

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Now I will clear the screen and we can do something more interesting.

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Let's say that we want to create script which will print first.

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So the lines of B s command but only in the case they use it or who are running it is rude.

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The best way out to get no vote user is running descript Vody by using user ID we can print it using

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equal dollar sign you I.D. here you see that my user ID is one thousand user id of root is zero.

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You can check Basford file

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and yes it does.

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Similarly my user ID is confirmed to be 1000 but checking user ID would be a great example for mathematical

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comparison and definitely you can try it on your own as a homework but as our lecture is about string

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comparison we can use command where my what I will tell you what user you are.

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So let's create a script called who don't as page

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first line is usually dedicated to having been Bysshe on the next line.

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I will print comment.

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So we exactly know what we are going to show.

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Three lines of B.S. come on only two road user

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then our next line grade the variable.

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Who am I.

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And assigned to it using command substitution output of command.

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Boy am I.

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Now we can write if condition.

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So inside single square brackets right dollar sign.

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When I read double quotation marks of course then exclamation mark equal sign road road is also in double

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quotation marks.

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So if that condition is true that means if the user is not the root we can bring in.

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You are not rude

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exotic and of course we can exit with Stupples for example one

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statement is not needed.

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Just close the if statement.

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And now we want to displace three lines of B s command.

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So B S Desch eat f by hat Desch.

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So the using command will print only first three lines of B as command.

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Save descript ground execute permission.

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And rallied.

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You are not rude exiting.

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Great.

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It is working.

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But to be sure I will switch to road user

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by typing.

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I will ensure that I am not home and now I can this could again

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great.

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I can see first the lines of B s command.

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It is working perfectly.

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I can now close the root session using exit keyboard and ensure that I am Richard.

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Again.