Difference between revisions of "BOSS-Linux/C2/Working-with-Regular-Files/English-timed"

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| 02:00
 
| 02:00
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|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.
+
|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'''.
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'''$ cp space test1 space test2''' and press '''Enter'''
+
  
 
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|-
 
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| 02:25
 
| 02:25
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|If '''test2''' doesn't exist it would be first created and then the content of '''test1''' will be copied to it.
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|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
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|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 '''Enter'''.
  
 
|-
 
|-
 
| 02:52
 
| 02:52
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|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'''.
+
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
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|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 name is '''demo2.'''
+
|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
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|To see that the demo2 is there type '''ls space /home/anirban''' and press '''Enter'''.
+
|To see that the 'demo2' is there, type: '''ls space /home/anirban''' and press '''Enter'''.
  
 
|-
 
|-
 
| 04:07
 
| 04:07
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|And as you can see here is '''demo2.'''
+
|And as you can see, here is '''demo2.'''
  
 
|-
 
|-
 
| 04:12
 
| 04:12
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|Before moving a head let us clear the screen.
+
|Before moving ahead, let us clear the screen.
  
 
|-
 
|-
 
| 04:17
 
| 04:17
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|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 '''Enter'''.
+
|Type: '''cp space /home/anirban/arc/demo1 space /home/anirban/''' and press '''Enter'''.
  
 
|-
 
|-
 
| 04:55
 
| 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.
+
|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
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|As before to see the '''demo1''' type '''ls/home/anirban''' and press '''Enter'''.
+
|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.
  
 
|-
 
|-
 
| 05:30
 
| 05:30
−
|Again before moving a head let us clear the screen.
+
|Again, before moving ahead, let us clear the screen.
  
 
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|-
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| 05:44
 
| 05:44
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|We assume that we have three files named '''test1 test2 test3''' in our home directory.
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|We assume that we have three files named '''test1, test2, test3''' in our '''home''' directory.
  
 
|-
 
|-
 
| 05:53
 
| 05:53
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|Now we type ''' cp space test1 space test2 space test3 space /home/anirban/testdir''' and press '''Enter'''.
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|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
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|You see that this files have actually been copied.We will type '''ls space /home/anirban/testdir''' and press '''Enter'''.
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|To see that these files have actually been copied, we will type: '''ls space /home/anirban/testdir''' and press '''Enter'''.
  
 
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| 06:58
 
| 06:58
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|There are many options that go with '''cp'''. Here we will see only the most important of them.
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|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 will go back to the slides.
+
|Let us first go back to the slides.
  
 
|-
 
|-
 
| 07:12
 
| 07:12
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|Among the options -R (The capital R) is an important one. It causes recursive copying of an entire directory structure.
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|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
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|Let us try to copy all the contents of the testdir directory to a directory called test.
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|Let us try to copy all the contents of the 'testdir' directory to a directory called 'test'.
 
   
 
   
 
|-
 
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| 07:36
 
| 07:36
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|For that we would type cp space testdir slash test and press '''Enter'''.
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|For that, we would type: '''cp space testdir slash test''' and press '''Enter'''.
  
 
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| 07:51
 
| 07:51
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|As you can see from the output message.
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|As you can see from the output message,
  
 
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| 07:54
 
| 07:54
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|Normally we cannot copy a directory having a some content directly with '''cp'' command.
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|normally we cannot copy a directory having some contents directly with the '''cp'' command.
  
 
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|Now we type ''' cp space -R(minus capital R) space testdir/ test''' and press '''Enter'''.
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|Now we type: ''' cp space -R(minus capital R) space testdir/ test''' and press '''Enter'''.
  
 
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|-
 
| 08:25
 
| 08:25
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|The files have now been copied, to see that the test directory actually exist type ls and press '''Enter'''.
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|The files have now been copied. To see that the test directory actually exists, type: '''ls''' and press '''Enter'''.
  
 
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| 08:37
 
| 08:37
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|As you can see the test directory exists. Let us clear the screen.
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|As you can see, the 'test' directory exists. Let us clear the screen.
  
 
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| 08:45
 
| 08:45
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|To see the contents inside test type '''ls test''' and press '''Enter'''.
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|To see the contents inside 'test', type: '''ls test''' and press '''Enter'''.
  
 
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| 08:57
 
| 08:57
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|You can see the contents of the test directory.
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|You can see the contents of the 'test' directory.
  
 
|-
 
|-
 
| 09:01
 
| 09:01
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|Now we go back to the slides.
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|Now, we go back to the slides.
  
 
|-
 
|-
 
| 09:05
 
| 09:05
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|We have seen if a file is copied to another file that already exists the existing file is overwritten.
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|We have seen if a file is copied to another file that already exists, the existing file is overwritten.
  
 
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|-
 
| 09:14
 
| 09:14
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|Now what if we inadvertently overwrite an important file?
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|Now, what if we inadvertently overwrite an important file?
  
 
|-
 
|-
 
| 09:19
 
| 09:19
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|To prevent anything like this to occur, we have the -b option.
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|To prevent anything like this to occur, we have the '-b' option.
  
 
|-
 
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| 09:25
 
| 09:25
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|This makes a backup of each exiting destination file.
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|This makes a '''backup''' of each existing destination file.
  
 
|-
 
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| 09:32
 
| 09:32
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|We can also use the -i(interactive)option, this always warns us before overwriting any destination file.  
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|We can also use the -i(interactive)option. This always warns us before overwriting any destination file.  
  
 
|-
 
|-
 
| 09:43
 
| 09:43
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|Now let us see how the '''mv''' command works.  
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|Now, let us see how the '''mv''' command works.  
  
 
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| 09:57
 
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|It is used for rename a file or directory.
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|It is used for renaming a file or directory.
  
 
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| 10:17
 
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|We open the terminal and type: '''mv space test1 space test2''' and press '''Enter'''.
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|We open the '''terminal''' and type: '''mv space test1 space test2''' and press '''Enter'''.
  
 
|-
 
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| 10:32
 
| 10:32
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|This will rename the file named '''test1''' which was already present in the '''home''' directory to a file named '''test2.'''  
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|This will '''rename''' the file named '''test1''' which was already present in the '''home''' directory to a file named '''test2.'''  
  
 
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| 10:59
 
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|Say we have another file named 'anirban'. This file we also want to renew as test2.  
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|Say we have another file named 'anirban'. This file we also want to renew as 'test2'.  
  
 
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| 12:09
 
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|Here are the files ''' pop.txt, push.txt''' and '''abc.txt''' Let us clear the screen.
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|Here are the files ''' pop.txt, push.txt''' and '''abc.txt'''. Let us clear the screen.
  
 
|-
 
|-

Revision as of 11:48, 11 August 2015

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 Then -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 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 this option is 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 option 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 file1 file2.
18: 47 If the two files have exactly same content 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 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.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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