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Linking files.

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Linking files is a great option in the Linux file system if you need to maintain two or more copies

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of the same file on the system instead of having a separate physical copies, you can use one physical

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copy and multiple virtual copies called links.

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Actually, yeah.

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Links here like this.

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Let me actually open our ergonomics grommet and write it right down here.

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Yeah.

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Here.

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Links.

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Of.

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So a link is a placeholder in a directory that points to real location of a file.

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So there is a two type of links here.

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So let's actually make it circle.

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And the first type is a symbolic link.

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Here.

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Symbolic.

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And the second type is hard link.

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So a symbolic link is a symbol of a physical file that points to another file somewhere in the virtual

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directory structure.

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So that's to symbolically link together files, do not share the same contents.

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So to create a symbolic link to a file, the original file must pre-exist.

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So you can you can then use the ln command with the s option to create a symbolic link here.

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So here, for example, let's write our file.

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And here open our file manager open folder.

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And for example, let's create a test file.

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Write something in it.

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Here.

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And.

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So we have some 531 31 bytes in it that we will write it here.

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So we will do LSL here, test file.

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And here, as you can see here, we have bytes and the test file here.

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And as you can see, we have seen our permissions here.

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So in order to do that, we will use ln s and for example, we will do it the test file.

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Firstly, we will pass our file, real file, and then we will sl here test file or you can.

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Yeah.

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You can also use it like that.

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Yeah.

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They don't have to share the same name or same name structure.

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So in this example here let's actually ls l and here in this example, notice that the name of the symbolic

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link is L data file.

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Test file is a listed second in the l n comma and as you can see here, so the the symbol here actually

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let me and as you can see, this is the symbol here.

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This this symbol here displayed after the symbolic link files, long listing shows that it is symbolically

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linked, symbolically linked to the file test file, as you can see here.

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So also, I want to note that that symbolic link file size versus the data file size.

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So the symbolic link is L file size here is only nine bytes where our data file has let me yeah, 531

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bytes in it.

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So this is because the as our s l test file is only pointing to our test file.

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So it actually doesn't contain any contents in it.

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So they do not share contents and are they are physically two separate files in our directory file system.

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But this only this file is only purpose to show that where our test file is.

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So another way to tell these linked files are separate physical files, but by viewing their inode number

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so the inode number of a file directory is a unique identification number that the kernel assigns to

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each object in the file system.

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So to view a file or directory is inode number, you can simply use the e parameter here.

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Actually it's clear and you can simply use E parameter right here.

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And then after that we will pass our test file, test file.

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And as you can see, this is our inode number for our test file and that's actually in here.

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And the oops, not like this.

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Let's clear this file.

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And then.

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We will do.

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Not like this.

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Yeah.

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Test file.

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We're going to write it right here.

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So test file.

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And here we will do SL test.

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File.

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And as you can see here, they are two different inode numbers.

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So remember that inode numbers are only assigned once in every file here.

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So there cannot be two inode files for now, but you will learn about inode numbers in next lectures.

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So.

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Another way to tell here that we can also.

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Yeah, this example showed us that the file inode number, our data file inode number is nine.

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Our data file inode number is 3932329.

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While our test file is 3932659.

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As you can see here.

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So a hard link creates a separate virtual file.

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So actually they are the different files.

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Right?

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We got it.

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Yeah, they are.

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The different files, the whole different files.

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But the hard link creates a separate virtual file that contains information about the original file

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and where to locate it.

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However, they are physically the same file.

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So when you reference the hard link file, it is just as if you are referencing the original file.

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So to create a hard link again, the original file must pre-exist.

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In this case, our original file is my test file.

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Except that this time there is a no parameter is needed on the command.

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In order to do that we're going to create LN So actually we learned about the symbolic line here.

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So we learned about symbolic.

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Now we're going to learn about the hard link lines.

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So now we're going to write ln my test file.

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My test file, and after that we're going to use the hard link.

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So in this case, as l that we mentioned, that ls l is a symbolic.

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And in this case let's actually write hard link to notify us that this is the hard link file or another

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users that notify us that this is a hard link file and not symbolic file symbolic link.

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So in this case let's actually

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test file.

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And here we created our hardlink file.

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Clear.

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LZ le LZ, L Yeah.

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Here.

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And let's find where.

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Yeah.

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As you can see here, this is test file Hardlink file.

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So in this example, actually, we need also.

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Great.

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Let's actually create the.

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First.

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Let's Yeah, let's actually and I will explain all of this here.

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Lee here.

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And we will make it what was actually what was our hardlink file here in this case is our test file

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and LSL here code.

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Caught ops?

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No, not caught here.

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Test File.

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Test file.

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And here, as you can see, zero bytes.

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And now let's actually use our.

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Our my test file.

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Yeah.

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Oh, actually I forgot about.

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We are working with.

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Yeah, it has to be test file.

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Yeah.

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Test file.

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In.

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Previously, we we actually created a wrong file name.

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We need to create a test file here so we will delete it.

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And as you can see, I'm going to show how it will hardlink files look like.

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And as you can see, WSL has a thick like this in the graphical interface but has doesn't have any things.

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And here, as you can see here, it's empty because we created from the empty file.

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Actually, my test file is empty as you can see here.

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So let's also delete this.

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Here.

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Yeah.

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Now we're going to use the test file, which is we've written some contents in it.

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Here and now we're going to use the LZ l e here.

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Oh, no.

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Firstly, we're going to create the ln or my test file.

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Or test file.

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Test file.

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And after that, my.

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Or test file.

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Right.

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Just the test file.

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File Create a hard link because the test file hard link is actually test file.

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My text file here.

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My test file.

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And we created our hard link.

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And now we're going to also show our hard link file here.

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So la la here.

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So in this case, we're going to.

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Use that test.

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Test file.

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File.

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And here, as you can see, we got another example.

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So in this example, we use the LSL command to show both the inode numbers and the long listing numbers

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for the code files.

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Actually, let's also show I want to show you how our inode number looks of our hardlink file, in this

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case, my test file.

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And here, as you can see here, these are inode numbers are the same.

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So.

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At these port files which are hard linked together, share the same inode number.

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This is because they are physically the same file.

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And as you can see, these all of them are the same size.

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This is because they are physically same file.

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And the.

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Here we have two links.

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In addition, their file size is exactly the same as well, so be careful when copying the linked files

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if you are using the CP command.

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Actually let's take it.

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Yeah.

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If you use the CP command to copy a file that's linked to another source file, all you are doing is

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making another copy of the source file so this can quickly get confusing.

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Instead of copying the link file, you can create another linked to the original file and you can have

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many links to the same file with no problems.

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However, you also don't want to create a soft links to the other to the other soft linked files.

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So this creates a chain of links that can be confusing and easily broken, causing all sorts of problems.

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So you may find symbolic and hard link difficult concepts.

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Fortunately, renaming files in the next lecture you is a great deal easier to understand that.

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So I'm waiting you in next lecture.