Difference between revisions of "BOSS-Linux/C2/Working-with-Regular-Files/English-timed"
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| 00:00 | | 00:00 | ||
− | |Welcome to this spoken tutorial on working with regular files in Linux. | + | |Welcome to this spoken tutorial on '''working with regular files''' in '''Linux'''. |
|- | |- | ||
| 00:07 | | 00:07 | ||
− | |Files and directories together form the Linux File System. | + | |Files and directories together form the '''Linux File System'''. |
|- | |- | ||
| 00:13 | | 00:13 | ||
− | |In a previous tutorial we have already seen how to work with directories. You can find the tutorial at this website. | + | |In a previous tutorial, we have already seen how to work with directories. You can find the tutorial at this website. |
|- | |- | ||
| 00:25 | | 00:25 | ||
− | |In this tutorial we will see how to handle regular files. | + | |In this tutorial, we will see how to handle '''regular files'''. |
|- | |- | ||
| 00:32 | | 00:32 | ||
− | |We have already seen in another tutorial how we can create a file using the '''cat''' command. For details please visit this website. | + | |We have already seen in another tutorial how we can create a file using the '''cat''' command. For details, please visit this website. |
|- | |- | ||
| 00:46 | | 00:46 | ||
− | |Let us see how to copy a file from one place to another. For this we have the '''cp''' command. | + | |Let us see how to copy a file from one place to another. For this, we have the '''cp''' command. |
|- | |- | ||
| 00:56 | | 00:56 | ||
− | |Let us see how the command is used. | + | |Let us see how the '''command''' is used. |
|- | |- | ||
| 01:00 | | 01:00 | ||
− | |To copy a single file we type '''cp''' space one or more of the [ | + | |To copy a single file, we type: '''cp''' space one or more of the [OPTIONs]... space the name of the SOURCE file space the name of the destination file. |
|- | |- | ||
| 01:15 | | 01:15 | ||
− | |To copy multiple files at the same time | + | |To copy multiple files at the same time, we write: cp space one or more of the [OPTIONs]...the name of the SOURCE files that we want to copy and the name of the destination DIRECTORY in which these files would be copied. |
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| 01:42 | | 01:42 | ||
− | |We already have a file named test1 in home directory | + | |We already have a file named "test1" in our '''home directory'''. |
|- | |- | ||
| 01:49 | | 01:49 | ||
− | |To see what is in '''test1''' | + | |To see what is in '''test1''', we type $ '''cat space test1''' and press '''Enter'''. |
|- | |- | ||
| 02:00 | | 02:00 | ||
− | |As we can see the content of '''test1''' is shown | + | |As we can see the content of '''test1''' is shown. Now if we want to copy it into another file called '''test2''', we would write: |
− | + | '''$ cp space test1 space test2''' and press '''Enter'''. | |
− | '''$ cp space test1 space test2''' and press | + | |
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| 02:25 | | 02:25 | ||
− | |If | + | |If 'test2' doesn't exist, it would be first created and then the content of 'test1' will be copied to it. |
|- | |- | ||
| 02:35 | | 02:35 | ||
− | |If it already existed then it would be silently overwritten.To see the copied file type | + | |If it already existed then it would be silently overwritten. To see the copied file, type: |
− | + | ''' cat test2''' and press '''Enter'''. | |
− | ''' cat test2''' and press | + | |
|- | |- | ||
| 02:52 | | 02:52 | ||
− | |We can also copy files from and to different directories.For example | + | |We can also copy files from and to different directories. For example- |
− | + | type: ''' cp space /home/anirban/arc/demo1''' which is the name of the file that we want to copy, '''space /home/anirban/demo2''' and press '''Enter'''. | |
− | + | ||
|- | |- | ||
| 03:32 | | 03:32 | ||
− | |What this will do is that it will copy the file | + | |What this will do is that it will copy the file 'demo1' from '''source''' diretory- '''/home/anirban/arc/''' to the destination directory- '''/home/anirban'''; it will copy to a file whose name is '''demo2.''' |
|- | |- | ||
| 03:51 | | 03:51 | ||
− | |To see that the demo2 is there type '''ls space /home/anirban''' and press | + | |To see that the 'demo2' is there, type: '''ls space /home/anirban''' and press '''Enter'''. |
|- | |- | ||
| 04:07 | | 04:07 | ||
− | |And as you can see here is '''demo2.''' | + | |And as you can see, here is '''demo2.''' |
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| 04:12 | | 04:12 | ||
− | |Before moving | + | |Before moving ahead, let us clear the screen. |
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| 04:17 | | 04:17 | ||
− | |If you want the file to have the same name in the destination directory, you may not even mention the file name.For example | + | |If you want the file to have the same name in the destination directory, you may not even mention the file name. For example- |
|- | |- | ||
| 04:27 | | 04:27 | ||
− | |Type '''cp space /home/anirban/arc/demo1 space /home/anirban/''' and press | + | |Type: '''cp space /home/anirban/arc/demo1 space /home/anirban/''' and press '''Enter'''. |
|- | |- | ||
| 04:55 | | 04:55 | ||
− | |This will again copy the file | + | |This will again copy the file 'demo1' presenting the '''/home/anirban/arc/ '''directory to '''/home/anirban''' directory to a file whose name will be 'demo1' as well. |
|- | |- | ||
| 05:11 | | 05:11 | ||
− | |As before to see the '''demo1''' type '''ls/home/anirban''' and press | + | |As before, to see the '''demo1''', type: '''ls/home/anirban''' and press '''Enter'''. |
|- | |- | ||
| 05:25 | | 05:25 | ||
− | | And as you can see the '''demo1''' file is there. | + | | And, as you can see the '''demo1''' file is there. |
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| 05:30 | | 05:30 | ||
− | |Again before moving | + | |Again, before moving ahead, let us clear the screen. |
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| 05:44 | | 05:44 | ||
− | |We assume that we have three files named '''test1 test2 test3''' in our home directory. | + | |We assume that we have three files named '''test1, test2, test3''' in our '''home''' directory. |
|- | |- | ||
| 05:53 | | 05:53 | ||
− | |Now we type ''' cp space test1 space test2 space test3 space /home/anirban/testdir''' and press | + | |Now, we type: ''' cp space test1 space test2 space test3 space /home/anirban/testdir''' and press '''Enter'''. |
− | + | ||
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| 06:16 | | 06:16 | ||
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| 06:30 | | 06:30 | ||
− | | | + | |To see that these files have actually been copied, we will type: '''ls space /home/anirban/testdir''' and press '''Enter'''. |
|- | |- | ||
| 06:52 | | 06:52 | ||
|As you can see '''test1,test2''' and '''test3''' are present in this directory. | |As you can see '''test1,test2''' and '''test3''' are present in this directory. | ||
− | |||
|- | |- | ||
| 06:58 | | 06:58 | ||
− | |There are many options that go with '''cp'''. Here we will see only the most important of them. | + | |There are many options that go with '''cp'''. Here, we will see only the most important of them. |
|- | |- | ||
| 07:07 | | 07:07 | ||
− | |Let us first | + | |Let us first go back to the slides. |
|- | |- | ||
| 07:12 | | 07:12 | ||
− | |Among the options -R (The capital R) is an important one. It causes recursive copying of an entire directory structure. | + | |Among the options, -R (The capital R) is an important one. It causes recursive copying of an entire directory structure. |
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| 07:27 | | 07:27 | ||
− | |Let us try to copy all the contents of the testdir directory to a directory called test. | + | |Let us try to copy all the contents of the 'testdir' directory to a directory called 'test'. |
|- | |- | ||
| 07:36 | | 07:36 | ||
− | |For that we would type cp space testdir slash test and press | + | |For that, we would type: '''cp space testdir slash test''' and press '''Enter'''. |
|- | |- | ||
| 07:51 | | 07:51 | ||
− | |As you can see from the output message | + | |As you can see from the output message, |
|- | |- | ||
| 07:54 | | 07:54 | ||
− | | | + | |normally we cannot copy a directory having some contents directly with the '''cp'' command. |
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| 08:07 | | 08:07 | ||
− | |Now we type ''' cp space -R(minus capital R) space testdir/ test''' and press | + | |Now we type: ''' cp space -R(minus capital R) space testdir/ test''' and press '''Enter'''. |
|- | |- | ||
| 08:25 | | 08:25 | ||
− | |The files have now been copied | + | |The files have now been copied. To see that the test directory actually exists, type: '''ls''' and press '''Enter'''. |
|- | |- | ||
| 08:37 | | 08:37 | ||
− | |As you can see the test directory exists. Let us clear the screen. | + | |As you can see, the 'test' directory exists. Let us clear the screen. |
|- | |- | ||
| 08:45 | | 08:45 | ||
− | |To see the contents inside test type '''ls test''' and press | + | |To see the contents inside 'test', type: '''ls test''' and press '''Enter'''. |
|- | |- | ||
| 08:57 | | 08:57 | ||
− | |You can see the contents of the test directory. | + | |You can see the contents of the 'test' directory. |
|- | |- | ||
| 09:01 | | 09:01 | ||
− | |Now we go back to the slides. | + | |Now, we go back to the slides. |
|- | |- | ||
| 09:05 | | 09:05 | ||
− | |We have seen if a file is copied to another file that already exists the existing file is overwritten. | + | |We have seen if a file is copied to another file that already exists, the existing file is overwritten. |
|- | |- | ||
| 09:14 | | 09:14 | ||
− | |Now what if we inadvertently overwrite an important file? | + | |Now, what if we inadvertently overwrite an important file? |
|- | |- | ||
| 09:19 | | 09:19 | ||
− | |To prevent anything like this to occur, we have the -b option. | + | |To prevent anything like this to occur, we have the '-b' option. |
|- | |- | ||
| 09:25 | | 09:25 | ||
− | |This makes a backup of each | + | |This makes a '''backup''' of each existing destination file. |
|- | |- | ||
| 09:32 | | 09:32 | ||
− | |We can also use the -i(interactive)option | + | |We can also use the -i(interactive)option. This always warns us before overwriting any destination file. |
|- | |- | ||
| 09:43 | | 09:43 | ||
− | |Now let us see how the '''mv''' command works. | + | |Now, let us see how the '''mv''' command works. |
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|- | |- | ||
| 09:57 | | 09:57 | ||
− | |It is used for | + | |It is used for renaming a file or directory. |
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|- | |- | ||
| 10:05 | | 10:05 | ||
− | |'''mv''' is very similar to '''cp''' which we have already seen. So let us quickly see how mv can be used. | + | |'''mv''' is very similar to '''cp''' which we have already seen. So, let us quickly see how '''mv''' can be used. |
|- | |- | ||
| 10:17 | | 10:17 | ||
− | |We open the terminal and type '''mv space test1 space test2''' and press | + | |We open the '''terminal''' and type: '''mv space test1 space test2''' and press '''Enter'''. |
|- | |- | ||
| 10:32 | | 10:32 | ||
− | |This will rename the file named '''test1''' which was already present in the home directory to a file named '''test2.''' | + | |This will '''rename''' the file named '''test1''' which was already present in the '''home''' directory to a file named '''test2.''' |
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| 10:49 | | 10:49 | ||
− | |If we want our warning before the file is overwritten | + | |If we want our warning before the file is overwritten, |
|- | |- | ||
| 10:54 | | 10:54 | ||
− | | | + | |we can use the ''' -i ''' option with the '''mv''' command. |
|- | |- | ||
| 10:59 | | 10:59 | ||
− | |Say we have another file named anirban. This file we also want to renew as test2 | + | |Say we have another file named 'anirban'. This file we also want to renew as 'test2'. |
|- | |- | ||
| 11:08 | | 11:08 | ||
− | |We will type ''' mv space -i space anirban space test2''' and press | + | |We will type: ''' mv space -i space anirban space test2''' and press '''Enter'''. |
|- | |- | ||
| 11:21 | | 11:21 | ||
− | |As you can see a warning is provided asking whether '''test2''' should be overwritten or not. | + | |As you can see, a warning is provided asking whether '''test2''' should be overwritten or not. |
|- | |- | ||
| 11:30 | | 11:30 | ||
− | |If we press y and then press | + | |If we press 'y' and then press '''Enter''', the file would be actually overwritten. |
|- | |- | ||
| 11:37 | | 11:37 | ||
− | |Like cp we can use mv with multiple files but in that case the destination should be a directory. | + | |Like '''cp''', we can use '''mv''' with multiple files but in that case the destination should be a directory. |
|- | |- | ||
| 11:47 | | 11:47 | ||
− | |Before moving ahead let us clear the screen. | + | |Before moving ahead, let us clear the screen. |
|- | |- | ||
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| 12:03 | | 12:03 | ||
− | |To see | + | |To see their presence, type ''' ls''' and press '''Enter'''. |
|- | |- | ||
| 12:09 | | 12:09 | ||
− | |Here are the files ''' pop.txt, push.txt''' and '''abc.txt''' Let us clear the screen. | + | |Here are the files ''' pop.txt, push.txt''' and '''abc.txt'''. Let us clear the screen. |
|- | |- | ||
| 12:24 | | 12:24 | ||
− | |Now we want to move | + | |Now we want to move these three files to a directory called '''testdir.''' |
|- | |- | ||
| 12:32 | | 12:32 | ||
− | |What we need to do is type ''' mv space abc.txt pop.txt push.txt''' and then the name of the destination folder which is '''testdir''' and press | + | |What we need to do is, type: ''' mv space abc.txt pop.txt push.txt''' and then the name of the destination folder which is '''testdir''' and press '''Enter'''. |
|- | |- | ||
| 12:58 | | 12:58 | ||
− | |To see them type ''' ls testdir ''' and press | + | |To see them, type: ''' ls testdir ''' and press '''Enter'''. |
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| 13:14 | | 13:14 | ||
− | |Now let us see some options that go with '''mv''''. Let us first go back to the slides. | + | |Now, let us see some options that go with '''mv''''. Let us first go back to the slides. |
|- | |- | ||
| 13:22 | | 13:22 | ||
− | | | + | |The '-b' or '–backup' option is present with the '''mv''' command. It will backup every file in the destination before it is overwritten. |
|- | |- | ||
| 13:34 | | 13:34 | ||
− | |The -i(minus i) option that we have already seen warns us before overwriting any destination file. | + | |The '-i' (minus i) option that we have already seen, warns us before overwriting any destination file. |
|- | |- | ||
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|- | |- | ||
| 13:52 | | 13:52 | ||
− | |Go back to the terminal and type '''ls testdir.''' | + | |Go back to the terminal and type: '''ls testdir.''' |
|- | |- | ||
| 14:00 | | 14:00 | ||
− | |We can see a file name | + | |We can see a file name 'faq.txt' present. Say we want to delete it. |
|- | |- | ||
| 14:09 | | 14:09 | ||
− | |For this we type ''' rm space testdir/faq.txt''' and press | + | |For this, we type: ''' rm space testdir/faq.txt''' and press '''Enter'''. |
|- | |- | ||
| 14:23 | | 14:23 | ||
− | |This command will remove the file | + | |This command will remove the file 'faq.txt' from the '''/testdir''' directory. |
|- | |- | ||
| 14:32 | | 14:32 | ||
− | |To see that the file has been actually removed or not | + | |To see that the file has been actually removed or not, let us again press ''' ls space testdir''' and press '''Enter'''. |
|- | |- | ||
| 14:47 | | 14:47 | ||
− | |We can no longer see the file | + | |We can no longer see the file 'faq.txt'. |
|- | |- | ||
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| 14:57 | | 14:57 | ||
− | |The ''' testdir''' directory contains two files | + | |The ''' testdir''' directory contains two files 'abc2' and 'abc1.' |
|- | |- | ||
| 15:03 | | 15:03 | ||
− | |Suppose we want to remove | + | |Suppose, we want to remove these files- 'abc1' and 'abc2.' |
|- | |- | ||
| 15:09 | | 15:09 | ||
− | |For this we would type ''' rm space testdir/abc1 space testdir/abc2''' and press | + | |For this, we would type: ''' rm space testdir/abc1 space testdir/abc2''' and press '''Enter'''. |
|- | |- | ||
| 15:31 | | 15:31 | ||
− | |This | + | |This removes the files 'abc1' and 'abc2' from '''testdir''' directory. |
|- | |- | ||
| 15:39 | | 15:39 | ||
− | |To see that they have been removed type '''ls space testdir''' again.You can no longer see '''abc1'''' and '''abc2.''' | + | |To see that they have been removed, type: '''ls space testdir''' again. You can no longer see '''abc1'''' and '''abc2.''' |
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|- | |- | ||
| 15:58 | | 15:58 | ||
− | |Now let us go back to the slides. | + | |Now, let us go back to the slides. |
|- | |- | ||
| 16:02 | | 16:02 | ||
− | |Let us summarize what we just said | + | |Let us summarize what we just said. |
|- | |- | ||
| 16:04 | | 16:04 | ||
− | |That is | + | |That is, to delete a single file we write '''rm''' and then the name of the file. |
|- | |- | ||
| 16:11 | | 16:11 | ||
− | |To delete multiple files we write '''rm''' and the name of the multiple files that we want to delete. | + | |To delete multiple files, we write '''rm''' and the name of the multiple files that we want to delete. |
|- | |- | ||
| 16:19 | | 16:19 | ||
− | |Now let us look into some of the options of the '''rm''' command. | + | |Now, let us look into some of the options of the '''rm''' command. |
|- | |- | ||
| 16:24 | | 16:24 | ||
− | |Sometimes a file is write protected | + | |Sometimes a file is '''write''' protected. Using '''rm''' will not delete the file then. In this case, we have the '''-f''' option which can be used to force delete a file. |
|- | |- | ||
| 16:41 | | 16:41 | ||
− | |The other common option is the '''-r''' option. Let us see where | + | |The other common option is the '''-r''' option. Let us see where these option are useful? |
|- | |- | ||
| 16:52 | | 16:52 | ||
− | |Let us switch back to the terminal. | + | |Let us switch back to the '''terminal'''. |
|- | |- | ||
| 16:57 | | 16:57 | ||
− | |'''rm''' command is not normally used for deleting directories | + | |'''rm''' command is not normally used for deleting directories. For that, we have the '''rmdir''' command. |
|- | |- | ||
| 17:05 | | 17:05 | ||
− | |But '''rmdir''' command normally deletes a directory only | + | |But '''rmdir''' command normally deletes a directory only when it is empty. |
|- | |- | ||
| 17:12 | | 17:12 | ||
− | |What if we want to delete a directory that has a number of files and | + | |What if we want to delete a directory that has a number of files and sub-directories inside? |
|- | |- | ||
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|- | |- | ||
| 17:23 | | 17:23 | ||
− | |Let us type '''rm''' and the directory that we want to delete which is '''testdir''' and press | + | |Let us type '''rm''' and the directory that we want to delete which is '''testdir''' and press '''Enter'''. |
− | + | ||
|- | |- | ||
| 17:31 | | 17:31 | ||
− | |From the output message we can see that we can not use the '''rm''' directory to delete testdir. | + | |From the output message, we can see that we can not use the '''rm''' directory to delete 'testdir'. |
|- | |- | ||
| 17:39 | | 17:39 | ||
− | |But if we combine the -r and -f | + | |But if we combine the '-r' and '-f' options then we can do this. |
|- | |- | ||
| 17:47 | | 17:47 | ||
− | |Press ''' rm -rf testdir''' and then press | + | |Press ''' rm -rf testdir''' and then press '''Enter'''. |
|- | |- | ||
| 18:00 | | 18:00 | ||
− | |Now the '''testdir''' directory has been successfully deleted. | + | |Now, the '''testdir''' directory has been successfully deleted. |
|- | |- | ||
| 18:06 | | 18:06 | ||
− | |Let us now go back to the slides to study the next command | + | |Let us now go back to the slides to study the next command- |
|- | |- | ||
| 18:11 | | 18:11 | ||
− | | | + | |the '''cmp''' command. |
|- | |- | ||
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|- | |- | ||
| 18:28 | | 18:28 | ||
− | |For these and many other purposes we can use the '''cmp''' command. | + | |For these and many other purposes, we can use the '''cmp''' command. |
|- | |- | ||
Line 478: | Line 472: | ||
|- | |- | ||
− | | 18:38 | + | |18:38 |
− | |To compare file1 and file2 we would write '''cmp file1 file2.''' | + | |To compare 'file1' and 'file2', we would write '''cmp space file1 space file2.''' |
|- | |- | ||
− | | 18: 47 | + | |18:47 |
− | |If the two files have exactly same | + | |If the two files have exactly the same contents then no message would be shown. |
|- | |- | ||
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|- | |- | ||
− | | 18:58 | + | |18:58 |
− | |If there are differences in their contents then the location of the first mismatch will be printed on the terminal. | + | |If there are differences in their contents then the location of the first mismatch will be printed on the '''terminal'''. |
|- | |- | ||
| 19:10 | | 19:10 | ||
− | |Let us see how '''cmp''' works.We have two files named '''sample1''' and '''sample2''' in our home directory. | + | |Let us see how '''cmp''' works. We have two files named '''sample1''' and '''sample2''' in our '''home''' directory. |
|- | |- | ||
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|- | |- | ||
− | | 19:22 | + | |19:22 |
− | |Type '''cat sample1''' and press | + | |Type: '''cat sample1''' and press '''Enter'''. It contains the text- '''"This is a Linux file to test the cmp command"'''. |
|- | |- | ||
− | | 19:34 | + | |19:34 |
− | |The other file '''sample2''' will contain the text and to see that we will type '''cat sample2''' and press | + | |The other file '''sample2''' will contain the text and to see that we will type: '''cat sample2''' and press '''Enter'''. |
|- | |- | ||
| 19:44 | | 19:44 | ||
− | |It will contain the text '''This is a Unix file to test the cmp command | + | |It will contain the text- '''"This is a Unix file to test the cmp command"'''. |
|- | |- | ||
| 19:50 | | 19:50 | ||
− | |Now we would apply the '''cmp''' command on | + | |Now we would apply the '''cmp''' command on these two files. |
|- | |- | ||
| 19:55 | | 19:55 | ||
− | |We will write '''cmp space sample1 space sample2''' and press | + | |We will write: '''cmp space sample1 space sample2''' and press '''Enter'''. |
|- | |- | ||
| 20:08 | | 20:08 | ||
− | |As we can see the first difference between the two files '''sample1''' and '''sample2''' is pointed out. | + | |As we can see, the first difference between the two files '''sample1''' and '''sample2''' is pointed out. |
|- | |- | ||
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|- | |- | ||
| 20:34 | | 20:34 | ||
− | |We have a file named | + | |We have a file named "sample3" in our '''home directory'''. |
|- | |- | ||
| 20:39 | | 20:39 | ||
− | |Let us see its | + | |Let us see its contents. For that, we will type: '''cat space sample3''' and press '''Enter'''. |
|- | |- | ||
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|- | |- | ||
| 20:54 | | 20:54 | ||
− | |Now let us use the wc command on this file. | + | |Now, let us use the '''wc''' command on this file. |
|- | |- | ||
| 20:59 | | 20:59 | ||
− | |For that we would write '''wc sample3''' and press | + | |For that, we would write '''wc space sample3''' and press '''Enter'''. |
|- | |- | ||
| 21:10 | | 21:10 | ||
− | | | + | |This command points out that the file has 6 lines, 67 words and 385 characters. |
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| 21:22 | | 21:22 | ||
− | |These were some of the commands that help us to work with files. | + | |These were some of the '''commands''' that help us to work with files. |
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− | | Spoken Tutorial Project is a part of the Talk to a Teacher project, supported by the National Mission on Education through ICT, MHRD, Government of India. | + | | Spoken Tutorial Project is a part of the "Talk to a Teacher" project, supported by the National Mission on Education through ICT, MHRD, Government of India. |
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| 22:02 | | 22:02 | ||
− | |More information on the same is available at the following link http://spoken-tutorial.org/NMEICT-Intro. | + | |More information on the same is available at the following link- http://spoken-tutorial.org/NMEICT-Intro. |
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− | |This is Anirban signing off . Thanks for joining. | + | |This is Anirban, signing off . Thanks for joining. |
Latest revision as of 11:53, 24 March 2017
Time | Narration |
00:00 | Welcome to this spoken tutorial on working with regular files in Linux. |
00:07 | Files and directories together form the Linux File System. |
00:13 | In a previous tutorial, we have already seen how to work with directories. You can find the tutorial at this website. |
00:25 | In this tutorial, we will see how to handle regular files. |
00:32 | We have already seen in another tutorial how we can create a file using the cat command. For details, please visit this website. |
00:46 | Let us see how to copy a file from one place to another. For this, we have the cp command. |
00:56 | Let us see how the command is used. |
01:00 | To copy a single file, we type: cp space one or more of the [OPTIONs]... space the name of the SOURCE file space the name of the destination file. |
01:15 | To copy multiple files at the same time, we write: cp space one or more of the [OPTIONs]...the name of the SOURCE files that we want to copy and the name of the destination DIRECTORY in which these files would be copied. |
01:34 | Let us now see an Example. First we open a terminal. |
01:42 | We already have a file named "test1" in our home directory. |
01:49 | To see what is in test1, we type $ cat space test1 and press Enter. |
02:00 | As we can see the content of test1 is shown. Now if we want to copy it into another file called test2, we would write:
$ cp space test1 space test2 and press Enter. |
02:22 | Now the file has been copied. |
02:25 | If 'test2' doesn't exist, it would be first created and then the content of 'test1' will be copied to it. |
02:35 | If it already existed then it would be silently overwritten. To see the copied file, type:
cat test2 and press Enter. |
02:52 | We can also copy files from and to different directories. For example-
type: cp space /home/anirban/arc/demo1 which is the name of the file that we want to copy, space /home/anirban/demo2 and press Enter. |
03:32 | What this will do is that it will copy the file 'demo1' from source diretory- /home/anirban/arc/ to the destination directory- /home/anirban; it will copy to a file whose name is demo2. |
03:51 | To see that the 'demo2' is there, type: ls space /home/anirban and press Enter. |
04:07 | And as you can see, here is demo2. |
04:12 | Before moving ahead, let us clear the screen. |
04:17 | If you want the file to have the same name in the destination directory, you may not even mention the file name. For example- |
04:27 | Type: cp space /home/anirban/arc/demo1 space /home/anirban/ and press Enter. |
04:55 | This will again copy the file 'demo1' presenting the /home/anirban/arc/ directory to /home/anirban directory to a file whose name will be 'demo1' as well. |
05:11 | As before, to see the demo1, type: ls/home/anirban and press Enter. |
05:25 | And, as you can see the demo1 file is there. |
05:30 | Again, before moving ahead, let us clear the screen. |
05:37 | Another instance when we do not need to give the destination file name is when we want to copy multiple files. |
05:44 | We assume that we have three files named test1, test2, test3 in our home directory. |
05:53 | Now, we type: cp space test1 space test2 space test3 space /home/anirban/testdir and press Enter. |
06:16 | This will copy all the three files named test1,test2 and test3 to the directory /home/anirban/testdir without changing their names. |
06:30 | To see that these files have actually been copied, we will type: ls space /home/anirban/testdir and press Enter. |
06:52 | As you can see test1,test2 and test3 are present in this directory. |
06:58 | There are many options that go with cp. Here, we will see only the most important of them. |
07:07 | Let us first go back to the slides. |
07:12 | Among the options, -R (The capital R) is an important one. It causes recursive copying of an entire directory structure. |
07:23 | Let us see an example. |
07:27 | Let us try to copy all the contents of the 'testdir' directory to a directory called 'test'. |
07:36 | For that, we would type: cp space testdir slash test and press Enter. |
07:51 | As you can see from the output message, |
07:54 | normally we cannot copy a directory having some contents directly with the 'cp command. |
08:02 | But using the -R (mius R ) option we can do this. |
08:07 | Now we type: cp space -R(minus capital R) space testdir/ test and press Enter. |
08:25 | The files have now been copied. To see that the test directory actually exists, type: ls and press Enter. |
08:37 | As you can see, the 'test' directory exists. Let us clear the screen. |
08:45 | To see the contents inside 'test', type: ls test and press Enter. |
08:57 | You can see the contents of the 'test' directory. |
09:01 | Now, we go back to the slides. |
09:05 | We have seen if a file is copied to another file that already exists, the existing file is overwritten. |
09:14 | Now, what if we inadvertently overwrite an important file? |
09:19 | To prevent anything like this to occur, we have the '-b' option. |
09:25 | This makes a backup of each existing destination file. |
09:32 | We can also use the -i(interactive)option. This always warns us before overwriting any destination file. |
09:43 | Now, let us see how the mv command works. |
09:47 | This is used for moving files. Now how is that useful? |
09:53 | It has two major uses. |
09:57 | It is used for renaming a file or directory. |
10:00 | It also moves a group of files to a different directory. |
10:05 | mv is very similar to cp which we have already seen. So, let us quickly see how mv can be used. |
10:17 | We open the terminal and type: mv space test1 space test2 and press Enter. |
10:32 | This will rename the file named test1 which was already present in the home directory to a file named test2. |
10:40 | If test2 already existed then it would be overwritten silently. |
10:49 | If we want our warning before the file is overwritten, |
10:54 | we can use the -i option with the mv command. |
10:59 | Say we have another file named 'anirban'. This file we also want to renew as 'test2'. |
11:08 | We will type: mv space -i space anirban space test2 and press Enter. |
11:21 | As you can see, a warning is provided asking whether test2 should be overwritten or not. |
11:30 | If we press 'y' and then press Enter, the file would be actually overwritten. |
11:37 | Like cp, we can use mv with multiple files but in that case the destination should be a directory. |
11:47 | Before moving ahead, let us clear the screen. |
11:52 | Suppose we have 3 files named abc.txt, pop.txt and push.txt in our home directory. |
12:03 | To see their presence, type ls and press Enter. |
12:09 | Here are the files pop.txt, push.txt and abc.txt. Let us clear the screen. |
12:24 | Now we want to move these three files to a directory called testdir. |
12:32 | What we need to do is, type: mv space abc.txt pop.txt push.txt and then the name of the destination folder which is testdir and press Enter. |
12:58 | To see them, type: ls testdir and press Enter. |
13:06 | You can see the files abc, pop and push.txt. |
13:14 | Now, let us see some options that go with mv'. Let us first go back to the slides. |
13:22 | The '-b' or '–backup' option is present with the mv command. It will backup every file in the destination before it is overwritten. |
13:34 | The '-i' (minus i) option that we have already seen, warns us before overwriting any destination file. |
13:44 | The next command we will see is the rm command. This command is used for deleting files. |
13:52 | Go back to the terminal and type: ls testdir. |
14:00 | We can see a file name 'faq.txt' present. Say we want to delete it. |
14:09 | For this, we type: rm space testdir/faq.txt and press Enter. |
14:23 | This command will remove the file 'faq.txt' from the /testdir directory. |
14:32 | To see that the file has been actually removed or not, let us again press ls space testdir and press Enter. |
14:47 | We can no longer see the file 'faq.txt'. |
14:51 | We can use the rm command with multiple files as well. |
14:57 | The testdir directory contains two files 'abc2' and 'abc1.' |
15:03 | Suppose, we want to remove these files- 'abc1' and 'abc2.' |
15:09 | For this, we would type: rm space testdir/abc1 space testdir/abc2 and press Enter. |
15:31 | This removes the files 'abc1' and 'abc2' from testdir directory. |
15:39 | To see that they have been removed, type: ls space testdir again. You can no longer see abc1' and abc2. |
15:53 | Let us clear the screen before moving ahead. |
15:58 | Now, let us go back to the slides. |
16:02 | Let us summarize what we just said. |
16:04 | That is, to delete a single file we write rm and then the name of the file. |
16:11 | To delete multiple files, we write rm and the name of the multiple files that we want to delete. |
16:19 | Now, let us look into some of the options of the rm command. |
16:24 | Sometimes a file is write protected. Using rm will not delete the file then. In this case, we have the -f option which can be used to force delete a file. |
16:41 | The other common option is the -r option. Let us see where these option are useful? |
16:52 | Let us switch back to the terminal. |
16:57 | rm command is not normally used for deleting directories. For that, we have the rmdir command. |
17:05 | But rmdir command normally deletes a directory only when it is empty. |
17:12 | What if we want to delete a directory that has a number of files and sub-directories inside? |
17:19 | Let us try the rm command to do this. |
17:23 | Let us type rm and the directory that we want to delete which is testdir and press Enter. |
17:31 | From the output message, we can see that we can not use the rm directory to delete 'testdir'. |
17:39 | But if we combine the '-r' and '-f' options then we can do this. |
17:47 | Press rm -rf testdir and then press Enter. |
18:00 | Now, the testdir directory has been successfully deleted. |
18:06 | Let us now go back to the slides to study the next command- |
18:11 | the cmp command. |
18:13 | Sometimes we need to check whether two files are same. If they are same then we may delete one of them. |
18:22 | Also we may want to see whether a file has changed since the last version. |
18:28 | For these and many other purposes, we can use the cmp command. |
18:33 | It compares two files byte by byte. |
18:38 | To compare 'file1' and 'file2', we would write cmp space file1 space file2. |
18:47 | If the two files have exactly the same contents then no message would be shown. |
18:55 | Only the prompt will be printed. |
18:58 | If there are differences in their contents then the location of the first mismatch will be printed on the terminal. |
19:10 | Let us see how cmp works. We have two files named sample1 and sample2 in our home directory. |
19:19 | Let us see what they contain? |
19:22 | Type: cat sample1 and press Enter. It contains the text- "This is a Linux file to test the cmp command". |
19:34 | The other file sample2 will contain the text and to see that we will type: cat sample2 and press Enter. |
19:44 | It will contain the text- "This is a Unix file to test the cmp command". |
19:50 | Now we would apply the cmp command on these two files. |
19:55 | We will write: cmp space sample1 space sample2 and press Enter. |
20:08 | As we can see, the first difference between the two files sample1 and sample2 is pointed out. |
20:16 | Let us clear the screen before moving ahead to the next command. |
20:22 | The next command we will see is the wc command. |
20:26 | This command is used to count the number of characters, words and lines in a file. |
20:34 | We have a file named "sample3" in our home directory. |
20:39 | Let us see its contents. For that, we will type: cat space sample3 and press Enter. |
20:50 | This is the content of sample3. |
20:54 | Now, let us use the wc command on this file. |
20:59 | For that, we would write wc space sample3 and press Enter. |
21:10 | This command points out that the file has 6 lines, 67 words and 385 characters. |
21:22 | These were some of the commands that help us to work with files. |
21:27 | There are many more commands. Moreover each of the command that we saw has many other options. |
21:36 | I encourage you to see more about them using the man command. |
21:44 | This brings me to the end of this tutorial at last. |
21:48 | Spoken Tutorial Project is a part of the "Talk to a Teacher" project, supported by the National Mission on Education through ICT, MHRD, Government of India. |
22:02 | More information on the same is available at the following link- http://spoken-tutorial.org/NMEICT-Intro. |
22:18 | This is Anirban, signing off . Thanks for joining. |