WEBVTT 00:01.170 --> 00:02.490 Linking files. 00:02.520 --> 00:09.300 Linking files is a great option in the Linux file system if you need to maintain two or more copies 00:09.300 --> 00:14.820 of the same file on the system instead of having a separate physical copies, you can use one physical 00:14.820 --> 00:18.600 copy and multiple virtual copies called links. 00:18.630 --> 00:19.740 Actually, yeah. 00:19.770 --> 00:21.060 Links here like this. 00:21.150 --> 00:28.350 Let me actually open our ergonomics grommet and write it right down here. 00:28.800 --> 00:29.610 Yeah. 00:29.610 --> 00:30.570 Here. 00:30.600 --> 00:31.680 Links. 00:34.060 --> 00:34.270 Of. 00:40.100 --> 00:48.760 So a link is a placeholder in a directory that points to real location of a file. 00:48.770 --> 00:51.880 So there is a two type of links here. 00:51.890 --> 00:54.710 So let's actually make it circle. 00:54.710 --> 00:59.810 And the first type is a symbolic link. 01:03.190 --> 01:03.590 Here. 01:03.640 --> 01:04.840 Symbolic. 01:08.810 --> 01:12.110 And the second type is hard link. 01:17.060 --> 01:24.350 So a symbolic link is a symbol of a physical file that points to another file somewhere in the virtual 01:24.350 --> 01:25.430 directory structure. 01:25.430 --> 01:31.910 So that's to symbolically link together files, do not share the same contents. 01:31.910 --> 01:36.920 So to create a symbolic link to a file, the original file must pre-exist. 01:36.920 --> 01:43.070 So you can you can then use the ln command with the s option to create a symbolic link here. 01:43.070 --> 01:48.470 So here, for example, let's write our file. 01:50.060 --> 01:53.330 And here open our file manager open folder. 01:53.840 --> 01:57.500 And for example, let's create a test file. 01:57.510 --> 01:58.820 Write something in it. 02:00.440 --> 02:01.010 Here. 02:04.030 --> 02:04.780 And. 02:05.550 --> 02:12.300 So we have some 531 31 bytes in it that we will write it here. 02:12.300 --> 02:16.440 So we will do LSL here, test file. 02:16.440 --> 02:22.500 And here, as you can see here, we have bytes and the test file here. 02:22.500 --> 02:25.800 And as you can see, we have seen our permissions here. 02:25.800 --> 02:33.240 So in order to do that, we will use ln s and for example, we will do it the test file. 02:33.240 --> 02:40.980 Firstly, we will pass our file, real file, and then we will sl here test file or you can. 02:40.980 --> 02:41.190 Yeah. 02:41.190 --> 02:42.780 You can also use it like that. 02:42.780 --> 02:43.290 Yeah. 02:43.410 --> 02:47.760 They don't have to share the same name or same name structure. 02:47.880 --> 02:56.880 So in this example here let's actually ls l and here in this example, notice that the name of the symbolic 02:56.880 --> 03:00.240 link is L data file. 03:00.510 --> 03:12.220 Test file is a listed second in the l n comma and as you can see here, so the the symbol here actually 03:12.220 --> 03:14.710 let me and as you can see, this is the symbol here. 03:14.710 --> 03:22.900 This this symbol here displayed after the symbolic link files, long listing shows that it is symbolically 03:22.930 --> 03:30.580 linked, symbolically linked to the file test file, as you can see here. 03:31.150 --> 03:37.660 So also, I want to note that that symbolic link file size versus the data file size. 03:37.660 --> 03:50.440 So the symbolic link is L file size here is only nine bytes where our data file has let me yeah, 531 03:50.440 --> 03:51.520 bytes in it. 03:51.700 --> 04:01.240 So this is because the as our s l test file is only pointing to our test file. 04:01.240 --> 04:03.640 So it actually doesn't contain any contents in it. 04:04.580 --> 04:14.030 So they do not share contents and are they are physically two separate files in our directory file system. 04:14.030 --> 04:21.770 But this only this file is only purpose to show that where our test file is. 04:23.050 --> 04:29.290 So another way to tell these linked files are separate physical files, but by viewing their inode number 04:29.290 --> 04:35.950 so the inode number of a file directory is a unique identification number that the kernel assigns to 04:35.950 --> 04:37.660 each object in the file system. 04:37.660 --> 04:45.820 So to view a file or directory is inode number, you can simply use the e parameter here. 04:46.030 --> 04:50.560 Actually it's clear and you can simply use E parameter right here. 04:50.560 --> 04:55.030 And then after that we will pass our test file, test file. 04:55.300 --> 05:03.760 And as you can see, this is our inode number for our test file and that's actually in here. 05:03.760 --> 05:06.340 And the oops, not like this. 05:08.540 --> 05:11.360 Let's clear this file. 05:11.360 --> 05:12.080 And then. 05:16.490 --> 05:17.510 We will do. 05:18.230 --> 05:19.040 Not like this. 05:19.040 --> 05:19.450 Yeah. 05:19.880 --> 05:20.330 Test file. 05:20.330 --> 05:21.860 We're going to write it right here. 05:22.190 --> 05:24.500 So test file. 05:24.500 --> 05:29.510 And here we will do SL test. 05:31.040 --> 05:31.730 File. 05:32.980 --> 05:37.870 And as you can see here, they are two different inode numbers. 05:37.990 --> 05:43.660 So remember that inode numbers are only assigned once in every file here. 05:43.660 --> 05:50.890 So there cannot be two inode files for now, but you will learn about inode numbers in next lectures. 05:51.830 --> 05:52.550 So. 05:54.700 --> 05:58.330 Another way to tell here that we can also. 05:58.960 --> 06:05.260 Yeah, this example showed us that the file inode number, our data file inode number is nine. 06:05.950 --> 06:10.300 Our data file inode number is 3932329. 06:10.660 --> 06:18.550 While our test file is 3932659. 06:18.760 --> 06:19.870 As you can see here. 06:19.870 --> 06:24.010 So a hard link creates a separate virtual file. 06:24.010 --> 06:26.020 So actually they are the different files. 06:26.020 --> 06:26.340 Right? 06:26.350 --> 06:27.030 We got it. 06:27.040 --> 06:27.640 Yeah, they are. 06:27.640 --> 06:29.590 The different files, the whole different files. 06:29.590 --> 06:35.140 But the hard link creates a separate virtual file that contains information about the original file 06:35.140 --> 06:37.060 and where to locate it. 06:37.060 --> 06:39.370 However, they are physically the same file. 06:39.370 --> 06:46.180 So when you reference the hard link file, it is just as if you are referencing the original file. 06:46.980 --> 06:53.460 So to create a hard link again, the original file must pre-exist. 06:53.460 --> 06:55.530 In this case, our original file is my test file. 06:55.890 --> 07:00.330 Except that this time there is a no parameter is needed on the command. 07:00.330 --> 07:06.540 In order to do that we're going to create LN So actually we learned about the symbolic line here. 07:06.540 --> 07:07.650 So we learned about symbolic. 07:07.650 --> 07:10.590 Now we're going to learn about the hard link lines. 07:10.590 --> 07:15.570 So now we're going to write ln my test file. 07:15.570 --> 07:19.110 My test file, and after that we're going to use the hard link. 07:19.110 --> 07:24.540 So in this case, as l that we mentioned, that ls l is a symbolic. 07:24.540 --> 07:29.730 And in this case let's actually write hard link to notify us that this is the hard link file or another 07:29.730 --> 07:35.940 users that notify us that this is a hard link file and not symbolic file symbolic link. 07:36.090 --> 07:39.300 So in this case let's actually 07:41.550 --> 07:43.530 test file. 07:45.120 --> 07:47.940 And here we created our hardlink file. 07:48.030 --> 07:48.870 Clear. 07:48.900 --> 07:52.920 LZ le LZ, L Yeah. 07:54.080 --> 07:54.770 Here. 07:56.090 --> 07:57.330 And let's find where. 07:57.380 --> 07:57.770 Yeah. 07:57.800 --> 08:01.120 As you can see here, this is test file Hardlink file. 08:01.130 --> 08:04.430 So in this example, actually, we need also. 08:05.690 --> 08:06.010 Great. 08:06.020 --> 08:08.450 Let's actually create the. 08:10.090 --> 08:10.510 First. 08:10.520 --> 08:14.440 Let's Yeah, let's actually and I will explain all of this here. 08:14.700 --> 08:15.490 Lee here. 08:15.490 --> 08:23.140 And we will make it what was actually what was our hardlink file here in this case is our test file 08:23.140 --> 08:26.920 and LSL here code. 08:27.860 --> 08:29.380 Caught ops? 08:29.420 --> 08:30.750 No, not caught here. 08:30.770 --> 08:31.430 Test File. 08:31.940 --> 08:33.050 Test file. 08:33.290 --> 08:35.880 And here, as you can see, zero bytes. 08:35.900 --> 08:38.630 And now let's actually use our. 08:40.050 --> 08:42.720 Our my test file. 08:44.170 --> 08:44.710 Yeah. 08:45.730 --> 08:47.100 Oh, actually I forgot about. 08:47.140 --> 08:48.340 We are working with. 08:48.370 --> 08:50.460 Yeah, it has to be test file. 08:50.470 --> 08:50.760 Yeah. 08:50.770 --> 08:51.580 Test file. 08:55.870 --> 08:56.050 In. 08:56.050 --> 08:59.260 Previously, we we actually created a wrong file name. 08:59.610 --> 09:03.670 We need to create a test file here so we will delete it. 09:03.670 --> 09:07.120 And as you can see, I'm going to show how it will hardlink files look like. 09:07.120 --> 09:14.140 And as you can see, WSL has a thick like this in the graphical interface but has doesn't have any things. 09:14.140 --> 09:18.360 And here, as you can see here, it's empty because we created from the empty file. 09:18.370 --> 09:20.500 Actually, my test file is empty as you can see here. 09:20.500 --> 09:23.230 So let's also delete this. 09:25.160 --> 09:25.600 Here. 09:25.670 --> 09:26.420 Yeah. 09:27.470 --> 09:31.140 Now we're going to use the test file, which is we've written some contents in it. 09:32.190 --> 09:39.420 Here and now we're going to use the LZ l e here. 09:41.610 --> 09:42.010 Oh, no. 09:42.030 --> 09:46.350 Firstly, we're going to create the ln or my test file. 09:46.380 --> 09:47.490 Or test file. 09:47.520 --> 09:48.840 Test file. 09:48.840 --> 09:51.060 And after that, my. 09:51.060 --> 09:52.230 Or test file. 09:52.320 --> 09:52.560 Right. 09:52.560 --> 09:53.520 Just the test file. 09:53.550 --> 09:58.140 File Create a hard link because the test file hard link is actually test file. 09:58.350 --> 09:59.760 My text file here. 09:59.760 --> 10:01.590 My test file. 10:01.590 --> 10:03.360 And we created our hard link. 10:03.360 --> 10:07.050 And now we're going to also show our hard link file here. 10:07.050 --> 10:10.230 So la la here. 10:10.230 --> 10:11.550 So in this case, we're going to. 10:13.270 --> 10:14.890 Use that test. 10:15.430 --> 10:16.840 Test file. 10:18.550 --> 10:19.030 File. 10:19.030 --> 10:21.550 And here, as you can see, we got another example. 10:21.550 --> 10:29.890 So in this example, we use the LSL command to show both the inode numbers and the long listing numbers 10:29.890 --> 10:31.000 for the code files. 10:31.000 --> 10:39.160 Actually, let's also show I want to show you how our inode number looks of our hardlink file, in this 10:39.160 --> 10:42.160 case, my test file. 10:42.160 --> 10:47.040 And here, as you can see here, these are inode numbers are the same. 10:47.050 --> 10:47.860 So. 10:49.640 --> 10:54.290 At these port files which are hard linked together, share the same inode number. 10:54.320 --> 10:56.750 This is because they are physically the same file. 10:57.110 --> 11:03.280 And as you can see, these all of them are the same size. 11:03.290 --> 11:05.270 This is because they are physically same file. 11:05.420 --> 11:06.560 And the. 11:07.790 --> 11:09.620 Here we have two links. 11:09.620 --> 11:16.610 In addition, their file size is exactly the same as well, so be careful when copying the linked files 11:16.610 --> 11:19.130 if you are using the CP command. 11:19.370 --> 11:20.500 Actually let's take it. 11:20.510 --> 11:20.810 Yeah. 11:20.810 --> 11:27.310 If you use the CP command to copy a file that's linked to another source file, all you are doing is 11:27.350 --> 11:31.420 making another copy of the source file so this can quickly get confusing. 11:31.430 --> 11:37.520 Instead of copying the link file, you can create another linked to the original file and you can have 11:37.520 --> 11:39.890 many links to the same file with no problems. 11:39.890 --> 11:47.090 However, you also don't want to create a soft links to the other to the other soft linked files. 11:47.090 --> 11:54.950 So this creates a chain of links that can be confusing and easily broken, causing all sorts of problems. 11:54.950 --> 11:58.640 So you may find symbolic and hard link difficult concepts. 11:58.640 --> 12:04.220 Fortunately, renaming files in the next lecture you is a great deal easier to understand that. 12:04.220 --> 12:06.140 So I'm waiting you in next lecture.