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Hello, the beautiful people.

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And welcome back.

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Now, in the last video, we put our files into a tar ball, and now we want to learn about how to compress

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that table to save space on our hard drive.

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Now, compression happens using compression algorithms, and there are two main compression algorithms

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in use in the Linux world, and the first is the GZIP algorithm and the second is B zip b zip two.

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And the main difference between them is usually GZIP is faster but has less compression power and b

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zip.

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Two on the other hand can generally compress files to a smaller size than GZIP, but does require more

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computational time.

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So both of these compression algorithms are really easy to use.

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So let's just start by talking about GZIP.

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So to compress a tarball using GZIP, all you need to do is type gzip and then the archive name.

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So who are our archive data and press enter and we'll see that that file has been compressed in place

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using the GZIP algorithm and we can see that it has.

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If we use the LZ command here, we can see that the dot GZ file extension has automatically been added

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and we can use the file command to confirm that.

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Yep, this is indeed GZIP compressed data and it was archived tar and it tells you when it was last

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modified as well.

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So that's really cool.

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We can see quite a lot of information about that.

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Now let's take a look at the file size.

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So if I do the LZ command with the L option, actually, no, that's just the L option.

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We'll see that.

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File one, file two and file three are 10,000 bytes in size.

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But our archive, the compressed archive is only 23,000 bytes, so it's about 7000 bytes or seven kilobytes

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less than what the files would have been originally.

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So we actually have managed to do a compression of about 23%.

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So that's not bad.

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Now this will vary from file type to file type and what you're actually compressing.

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But in this case, we've got a compression of 23% with GZIP.

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So notice how compression is a two stage thing.

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First we make a tarball and then we compress that tarball with a compression algorithm which in this

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case was GZIP.

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Okay, cool.

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So how about reversing the GZIP?

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How can we get the tar ball back?

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Well, this is very easy.

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All we need to do is just clear the screen.

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G Unzip our archive.

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GZ Okay, so you just use G unzip on whatever it was.

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And when you do that, you see it's now back to a tar file.

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And if we look, we can see that it's a tar file.

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We're using the file command to archive tar and it tells you it's a POSIX tar archive.

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Hooray.

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Okay, so we've managed to undo the GZIP operation.

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Okay, so what about B's zip two?

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Well, B, zip two is a more heavy duty compression algorithm, and it takes more computational time

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than GZIP, but usually not always, but usually returns more compressed files than you get with GZIP.

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So it's a bit of a tradeoff.

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Now let's compress our tarball with B's zip two and see what we get.

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So it's very easy.

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All we have to do is be zip to our archive tar and when we see that we now see that it's gone and got

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the Z to file extension and if we use the file command on it, we can see that it says it's b zip to

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compress data.

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It doesn't tell you what it was before it was compressed.

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So we lose a bit of that information.

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But it has indeed been compressed and the file command knows that it has.

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So how big is it?

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Well, if we take a look with the URL option, we can just have a look right there and we can see that

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this is 23,137 bytes.

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So it's slightly larger than the G's version of 23,023 bytes.

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Now, zip two is usually best saved until you have really large files.

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Now, for these relatively small text files, it didn't do as much good to use be zip two.

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But on a large file such as a video, you'll definitely see a large difference between the compression

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results achieved by B's zip two and G zip.

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Now to undo a B zip to compression, it's actually very easy.

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All we've got to do is be unzip to and then whatever the b zip to archive is.

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So in our case, this archive turned up easy too.

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And when we press enter, we see that we've come back to the tar file and again we can use the file

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command to check and we've got our tar archive back.

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Now there are other compression algorithms out there, such as the x z compression algorithm.

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And if you want to see a more in-depth comparison between the performance of G, Zip B's it too and

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the Z algorithm, I put a link in the resources section for you to find out.

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Now there is something that you should bear in mind, however, which is how do you create zip files?

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Now, zip files are files that you know are commonly used on Windows or Mac and, you know, as compressed

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archives.

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Now they're not in.

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I don't think they are as compressed as what you'll get with GZIP or zip too.

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But they.

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They are commonly used on other on other operating systems.

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So if you want to create a zip file, it's actually a one step process.

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You'll just type zip.

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Okay?

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Then you'll put the file.

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So let's, let's call it our thing, zip, and then we'll put file one point txt file to task and file

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three dot txt.

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And when we press enter, we'll see that we now have a zip file in there.

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So if I press file our file after thing, sorry, zip.

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It tells us that it's a zip archive data and this is what you can use on other operating systems such

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as Windows.

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And you usually can't with g zipped files or b zip to compressed files.

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They don't tend to work too well on other operating systems by default.

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You tend to have to install other software like seven zip or winrar or whatever it might be to extract

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them.

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And of course you can just unzip that zip file and it'll ask you, do you want to extract them all?

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And then you can extract them all.

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This is just extra asking us because it was like, Oh, you might have to overwrite some stuff, but

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that's no problem.

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We just said yes, and that worked.

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So if you want to make zip files, zip and unzip is the way to go.

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So if we clear the screen now, so far we've been looking at compression as a two step process.

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First, we've been creating a tar ball using the tar command and then compressing that tar ball using

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either GZIP or BS it two or, you know, any other compression algorithm.

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But is there any way to do it in one step?

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Well, because creating backups is such a common thing to do, the answer is yes, you can actually

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create a tarball and compress it using a compression algorithm straight from within the tar command.

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So let's just delete our tarball for now in our zip folder.

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So our to archive tar, we're going to remove that and our fingers zip.

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So we're going to get rid of all, every archive that we've got and then we're going to take it right

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from just the raw data here, these raw files straight to a compressed archive in one go.

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Okay.

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So to create the tab, to create the tar ball itself, how would we do that?

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Well, what we do is we create we do tar CBF, so create verbose and allow it to accept files.

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We're going to create our archive tar there we go and file 1 to 3.

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So this is the way that we normally do it.

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But now to compress the files, we just need to give it one more option.

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So to do it with GZIP, you just give it the Z option.

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And if, if we do that, that will compress using GZIP and we should remember that instead of naming

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it as our archive.

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TAR Because this is going to be a g zip file, we should add g z at the end as well just for convention

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because it won't be added automatically when using this method when you run GZIP on it before it was

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added automatically the GZ file extension.

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But now because we're doing it all in one step, we have to provide the file name, so we need to add

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it on there.

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Just so you know, it's a bit easier to see what's going on.

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And when we have when we press enter, we'll see that our archive GZ has been, has been created and

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we can check that it is in fact a zip file using the file command and it says that it is GZIP compressed

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data.

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So that's super cool.

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Okay, now how would you do it using B zip two.

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Well, if we clear the screen b's it two is exactly the same.

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Except instead of Z you just have J.

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So if you press, if you have J and now remember, we're going to change our extension to B zip two.

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And when we press enter, we'll see that our archive, zip too has been created and we can check that

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that is indeed valid by using the file command, telling it to look at the b zip to archive and it tells

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us that it's b zip two compressed data.

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So that's how you can compress in one go.

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How would we go about extracting from those compressed archives in one go?

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Well, that's really easy as well.

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Okay, let's delete them again.

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Actually, no, it's not delete them because we'll need them.

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Right.

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So here's how would we normally extract from a tar file.

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Well, how would normally do it, if you remember, is tar then x vrf and so x for extract, v for verbose

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and f to accept a file and you'd give it the the, the tar file.

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But let's try and extract the GZIP option first.

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Let's delete these original files and let's try and extract the the GZIP option first.

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So to extract the GZIP option we've got to do is type the Z again because Z is for GZIP.

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Okay, so you had this the Z when compressing, you have the Z when extracting, all you've got to do

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is change the C to an X and you're good to go.

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So when we press that, we'll see that now we've extracted them all out again and we've got the data

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back.

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So if we delete these files here, if we just delete them there.

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Now how about extracting using B's?

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YP Well, you remember that J is for B's.

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YP So instead of having Z, let's just put the J and then we just need to tell it what the archive is

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and remember that it's a B's YP to archive, so we need to actually change the name.

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So we are tar extracting verbose through b zip two and then giving it the file and.

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There we are.

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We've extracted using bees too.

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So it's very, very easy.

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As long as you can remember that Z is for GZIP.

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J is for bees too.

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You saw it and you can extract and compress all in one go.

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Hurray.

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So we've seen so much in the last two videos.

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It's quite hilarious that a section on compression would take so long.

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Right.

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Anyway, let's have a quick recap.

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So you first learned about the concept of a tar ball.

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Now tar files or tar balls are just containers for you to store the files that you want to compress.

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Now you can create tar balls using the tar command.

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And tar balls do not really do any compression on their own.

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That's the job of a compression algorithm.

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The tar ball just contains the files and you saw how to add files into tar balls and how to extract

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files from tar balls using the tar command.

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And remember that there's a cheat sheet in the resources section for this video that will list out the

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different options and different ways of using the tar command.

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Now, once you have the tar ball in order to compress it, you need to use a compression algorithm so

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tar balls can be compressed using a variety of different compression algorithms.

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And we took a look at GZIP and Bee Zip two, which are common options on Linux, but the Z option is

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another option.

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We didn't discuss it here, but if you want to read more about the comparison between the different

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algorithms, I've also put a link to a interesting blog post in the resources section for this video

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for you to have a look at as well.

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But with regards to GZIP and BBS, it to GZIP tends to be faster but give less compression, whereas

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BS YP too tends to give more compression but take a bit more computation time.

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So that's just something to bear in mind.

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But by all means check out the link in the resources section for a more in-depth discussion.

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You saw also how you can create zip files for compatibility with things like Windows or Mac using the

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zip and unzip commands.

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So that's something as well that you've got on record as well and you saw as well how to not just do

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making the tarball and then compressing in two steps.

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You saw how to do archiving and compression in just one step using a variety of shortcuts and all that

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stuff is in the cheat sheet that you can find in the resources section for this video.

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If you ever need a refresher, it's all very simple, and once you look at the cheat sheet, probably

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you'll be able to see the pattern.

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But it's really quite simple stuff once you've done it once or twice.

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Okay, so all in all, you can now create your own archives and backups using the Linux, using the

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Linux command line, which is super awesome because on this section all about learning how to use files.

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Now when you've created your files, you've edited them, they've copied the paste them, you've moved

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them, you've done whatever you want with them.

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You can also create your own backups and save for later in a say in a space efficient way.

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So well done, you.

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Now in the next video, what we're going to be doing is we're going to be closing our discussion for

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this section on files and the file system.

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And I want to say that you've really come so very far in this section.

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And the next video, I want to take the time to have a recap of what we've learned in this section and

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also to celebrate your progress.

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So well done you now for a summary of this section of the course, as well as some a deserved set of

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praises.

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I'll see you in the next video.