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

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|-
 
|-
| 00:31
+
| 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.
  
 
|-
 
|-
| 00:55
+
| 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
+
|To copy a single file we type '''cp''' space one or more of the [OPTION]... space the name of the SOURCE file space the name of the destination file  
cp space one or more of the [OPTION]... space the name of the SOURCE file space the name of the destination file DEST.
+
  
 
|-
 
|-
 
| 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 [OPTION]...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.
  We write cp space one or more of the [OPTION]...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
 
| 01:34
|Let us now see an Eg.First we open a terminal.  
+
|Let us now see an Example. First we open a terminal.  
  
 
|-
 
|-
 
| 01:42
 
| 01:42
|We already have a file named test1 in /home/anirban/arc/
+
|We already have a file named test1 in home directory
 
   
 
   
 
|-
 
|-
| 01:49
+
| 01:49
|To see what is in test1.We type
+
|To see what is in '''test1'''.We type  $ '''cat space test1''' and press enter.
  $ cat test1 and press enter.
+
  
 
|-
 
|-
 
| 02:00
 
| 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.  
+
|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 test1 test2 and press enter.
+
'''$ cp space test1 space test2''' and press enter.
  
 
|-
 
|-
Line 65: Line 62:
 
|-
 
|-
 
| 02:25
 
| 02:25
|If test2 doesn't exist it would be first created and then the content of test1 will be copied to it.
+
|If '''test2''' doesn't exist it would be first created and then the content of '''test1''' will be copied to it.
  
 
|-
 
|-
Line 71: Line 68:
 
|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
|You 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 /home/anirban/arc/demo1 /home/anirban/demo2 and press enter.
+
  
 
|-
 
|-
| 03:31
+
| 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 name 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 name is '''demo2.'''
  
 
|-
 
|-
 
| 03:51
 
| 03:51
|To see that the demo2 is there type
+
|To see that the demo2 is there type '''ls space /home/anirban''' and press enter.
ls space /home/anirban and press enter.
+
  
 
|-
 
|-
| 04:13
+
| 04:07
|We scroll up as you can see here is demo2.
+
|And as you can see here is '''demo2.'''
  
 
|-
 
|-
| 04:19
+
| 04:12
 
|Before moving a head let us clear the screen.
 
|Before moving a head let us clear the screen.
  
 
|-
 
|-
| 04:25
+
| 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
  
 
|-
 
|-
| 04:35
+
| 04:27
|Type $ cp /home/anirban/arc/demo1 /home/anirban/ and press enter.
+
|Type '''cp space /home/anirban/arc/demo1 space /home/anirban/''' and press enter.
  
 
|-
 
|-
| 05:03
+
| 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.
  
 
|-
 
|-
| 05:20
+
| 05:11
|As before to see the demo1 type
+
|As before to see the '''demo1''' type '''ls/home/anirban''' and press enter.
ls/home/anirban and press enter.
+
  
 
|-
 
|-
| 05:33
+
| 05:25
|Here again we would scroll up and as you can see the demo1 file is there.
+
| And as you can see the '''demo1''' file is there.
  
 
|-
 
|-
| 05:40
+
| 05:30
 
|Again before moving a head let us clear the screen.
 
|Again before moving a head let us clear the screen.
  
 
|-
 
|-
| 05:48
+
| 05:37
 
|Another instance when we do not need to give the destination file name is when we want to copy multiple files.
 
|Another instance when we do not need to give the destination file name is when we want to copy multiple files.
  
 
|-
 
|-
| 05:56
+
| 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.
  
 
|-
 
|-
| 06:04
+
| 05:53
|Now we type $ cp test1 test2 test3 /home/anirban/testdir and press enter.
+
|Now we type ''' cp space test1 space test2 space test3 space /home/anirban/testdir''' and press enter.
  
 
|-
 
|-
| 06:27
+
| 06:16
|This will copy all the three files test1,test2 and test3 to the directory /home/anirban/testdir without changing their names.  
+
|This will copy all the three files named '''test1,test2''' and '''test3''' to the directory ''' /home/anirban/testdir''' without changing their names.  
  
 
|-
 
|-
| 06:41
+
| 06:30
|You see that this files have actually been copied.We will type ls /home/anirban/testdir and press enter.
+
|You see that this files have actually been copied.We will type '''ls space /home/anirban/testdir''' and press enter.
  
 
|-
 
|-
| 07:03
+
| 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.
  
  
 
|-
 
|-
| 07:10
+
| 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.
  
 
|-
 
|-
| 07:18
+
| 07:07
 
|Let us first will go back to the slides.
 
|Let us first will go back to the slides.
  
 
|-
 
|-
| 07:23
+
| 07:12
|Among the options -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.
  
 
|-
 
|-
| 07:33
+
| 07:23
 
|Let us see an example.
 
|Let us see an example.
  
 
|-
 
|-
| 07:38
+
| 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.
 
   
 
   
 
|-
 
|-
| 07:48
+
| 07:36
|For that we would type cp testdir/ test and press enter.
+
|For that we would type cp space testdir slash test and press enter.
  
 
|-
 
|-
| 08:02
+
| 07:51
 
|As you can see from the output message.
 
|As you can see from the output message.
  
 
|-
 
|-
| 08:06
+
| 07:54
|Normally we cannot copy a directory having a some content directly with cp command.
+
|Normally we cannot copy a directory having a some content directly with '''cp'' command.
  
 
|-
 
|-
| 08:14
+
| 08:02
|But using the -R option we can do this.
+
|But using the -R (mius R ) option we can do this.
  
 
|-
 
|-
| 08:19
+
| 08:07
|Now we type cp -R testdir/ test and press enter.
+
|Now we type ''' cp space -R(minus capital R) space testdir/ test''' and press enter.
  
 
|-
 
|-
| 08:36
+
| 08:25
 
|The files have now been copied, to see that the test directory actually exist type ls and press enter.
 
|The files have now been copied, to see that the test directory actually exist type ls and press enter.
  
 
|-
 
|-
| 08:47
+
| 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.
  
 
|-
 
|-
| 08:57
+
| 08:45
|To see the contents inside test type ls test and press enter.
+
|To see the contents inside test type '''ls test''' and press enter.
  
 
|-
 
|-
| 09:08
+
| 08:57
 
|You can see the contents of the test directory.
 
|You can see the contents of the test directory.
  
 
|-
 
|-
| 09:13
+
| 09:01
 
|Now we go back to the slides.
 
|Now we go back to the slides.
  
 
|-
 
|-
| 09:16
+
| 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.
  
 
|-
 
|-
| 09:25
+
| 09:14
 
|Now what if we inadvertently overwrite an important file?
 
|Now what if we inadvertently overwrite an important file?
  
 
|-
 
|-
| 09:30
+
| 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.
  
 
|-
 
|-
| 09:36
+
| 09:25
 
|This makes a backup of each exiting destination file.
 
|This makes a backup of each exiting destination file.
  
 
|-
 
|-
| 09:41
+
| 09:32
 
|We can also use the -i(interactive)option, this always warns us before overwriting any destination file.  
 
|We can also use the -i(interactive)option, this always warns us before overwriting any destination file.  
  
 
|-
 
|-
| 09:54
+
| 09:43
|Now let us see how the mv command works.  
+
|Now let us see how the '''mv''' command works.  
  
 
|-
 
|-
| 09:59
+
| 09:47
 
|This is used for moving files. Now how is that useful?
 
|This is used for moving files. Now how is that useful?
  
 
|-
 
|-
| 10:04
+
| 09:53
 
|It has two major uses.
 
|It has two major uses.
  
 
|-
 
|-
| 10:07
+
| 09:57
 
|It is used for rename a file or directory.
 
|It is used for rename a file or directory.
  
 
|-
 
|-
| 10:11
+
| 10:00
 
|It also moves a group of files to a different directory.
 
|It also moves a group of files to a different directory.
  
 
|-
 
|-
| 10:17
+
| 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.  
  
 
|-
 
|-
| 10:29
+
| 10:17
|We open the terminal and type $ mv test1 test2 and press enter.
+
|We open the terminal and type '''mv space test1 space test2''' and press enter.
  
 
|-
 
|-
| 10:43
+
| 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.'''
  
 
|-
 
|-
| 10:52
+
| 10:40
|If test2 already existed then it would be overwritten silently.
+
|If '''test2''' already existed then it would be overwritten silently.
  
 
|-
 
|-
| 11:00
+
| 10:49
 
|If we want our warning before the file is overwritten.
 
|If we want our warning before the file is overwritten.
  
 
|-
 
|-
| 11:05
+
| 10:54
|We can use the -i option with the mv command.
+
|We can use the ''' -i ''' option with the mv command.
  
 
|-
 
|-
| 11:10
+
| 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  
  
 
|-
 
|-
| 11:20
+
| 11:08
|We will type mv -i anirban test2 and press enter.
+
|We will type ''' mv space  -i space anirban space test2''' and press enter.
  
 
|-
 
|-
| 11:32
+
| 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.  
  
 
|-
 
|-
| 11:41
+
| 11:30
 
|If we press y and then press enter, the file would be actually overwritten.
 
|If we press y and then press enter, the file would be actually overwritten.
  
 
|-
 
|-
| 11:49
+
| 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.
  
 
|-
 
|-
| 11:58
+
| 11:47
 
|Before moving ahead let us clear the screen.
 
|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
 
| 12:03
|Suppose we have 3 files named abc.txt, pop.txt and push.txt in our home directory.
+
|To see there presence type ''' ls''' and press enter.
  
 
|-
 
|-
| 12:14
+
| 12:09
|To see there presence type ls and press enter.
+
|Here are the files ''' pop.txt, push.txt''' and '''abc.txt''' Let us clear the screen.
  
 
|-
 
|-
| 12:21
+
| 12:24
|Here are the files pop.txt,push.txt and abc.txt Let us clear the screen.
+
|Now we want to move this three files to a directory called '''testdir.'''
  
 
|-
 
|-
| 12:36
+
| 12:32
|Now we want to move this three files to a directory called testdir.
+
|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.
  
 
|-
 
|-
| 12:46
+
| 12:58
|What we need to do is type mv abc.txt pop.txt push.txt and then the name of the destination folder which is testdir and press enter.
+
|To see them type ''' ls testdir ''' and press enter.
  
 
|-
 
|-
| 13:14
+
| 13:06
|To see them type ls testdir and press enter.
+
|You can see the files ''' abc, pop''' and '''push.txt.'''
  
 
|-
 
|-
| 13:20
+
| 13:14
|You can see the files abc, pop and push.txt.
+
|Now let us see some options that go with '''mv''''. Let us first go back to the slides.
  
 
|-
 
|-
| 13:27
+
| 13:22
|Now let us see some options that go with mv. Let us first go back to the slides.
+
|Then -b or –backup option is present with the '''mv''' command.It will backup every file in the destination before it is overwritten.  
  
 
|-
 
|-
| 13:37
+
| 13:34
|Then -b or –backup option is present with the mv command.It will backup every file in the destination before it is overwritten.  
+
|The -i(minus i) option that we have already seen warns us before overwriting any destination file.
  
 
|-
 
|-
| 13:48
+
| 13:44
|The -i option that we have already seen warns us before overwriting any destination file.
+
|The next command we will see is the '''rm''' command. This command is used for deleting files.  
  
 
|-
 
|-
| 13:58
+
| 13:52
|The next command we will see is the rm command. This command is used for deleting files.  
+
|Go back to the terminal and type '''ls testdir.'''
  
 
|-
 
|-
| 14:06
+
| 14:00
|Go back to the terminal and type ls testdir.
+
|We can see a file name '''faq.txt''' present. Say we want to delete it.
  
 
|-
 
|-
| 14:15
+
| 14:09
|We can see a file name faq.txt present.Say we want to delete it.
+
|For this we type ''' rm space testdir/faq.txt''' and press enter.
  
 
|-
 
|-
 
| 14:23
 
| 14:23
|For this we type
+
|This command will remove the file '''faq.txt''' from the '''/testdir''' directory.
$ rm testdir/faq.txt and press enter.
+
  
 
|-
 
|-
| 14:37
+
| 14:32
|This command will remove the file faq.txt from the /testdir directory.
+
|To see that the file has been actually removed or not. Let us again press ''' ls testdir''' and press enter.
  
 
|-
 
|-
| 14:46
+
| 14:47
|To see that the file has been actually removed or not.Let us again press ls testdir and press enter.
+
|We can no longer see the file ''' faq.txt.'''
  
 
|-
 
|-
| 15:00
+
| 14:51
|We can no longer see the file faq.txt.
+
|We can use the '''rm''' command with multiple files as well.
  
 
|-
 
|-
| 15:05
+
| 14:57
|We can use the rm command with multiple files as well.
+
|The ''' testdir''' directory contains two files '''abc2''' and '''abc1.'''
  
 
|-
 
|-
| 15:10
+
| 15:03
|The testdir directory contains two files abc2 and abc1.
+
|Suppose we want to remove this files '''abc1''' and '''abc2.'''
  
 
|-
 
|-
| 15:17
+
| 15:09
|Suppose we want to remove this files abc1 and abc2.
+
|For this we would type ''' rm space testdir/abc1 space testdir/abc2''' and press enter.
  
 
|-
 
|-
| 15:23
+
| 15:31
|For this we would type rm testdir/abc1 testdir/abc2 and press enter.
+
|This remove the files '''abc1''' and '''abc2''' from '''testdir''' directory.
  
 
|-
 
|-
| 15:45
+
| 15:39
|This remove the files abc1 and abc2 from testdir directory.
+
|To see that they have been removed type '''ls space testdir''' again.You can no longer see '''abc1'''' and '''abc2.'''
  
 
|-
 
|-
 
| 15:53
 
| 15:53
|To see that they have been removed type ls testdir again.You can no longer see abc1 and abc2.
 
 
|-
 
| 16:07
 
 
|Let us clear the screen before moving ahead.  
 
|Let us clear the screen before moving ahead.  
  
 
|-
 
|-
| 16:14
+
| 15:58
 
|Now let us go back to the slides.
 
|Now let us go back to the slides.
  
 
|-
 
|-
| 16:18
+
| 16:02
 
|Let us summarize what we just said?
 
|Let us summarize what we just said?
  
 
|-
 
|-
| 16:20
+
| 16:04
|That is do delete a single file we write rm and than the name of the file.
+
|That is do delete a single file we write '''rm''' and than the name of the file.
  
 
|-
 
|-
| 16:27
+
| 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.
  
 
|-
 
|-
| 16:34
+
| 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.
  
 
|-
 
|-
| 16:40
+
| 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.
+
|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.
  
 
|-
 
|-
| 16:57
+
| 16:41
|The other common option is the -r option. Let us see where this options are useful?
+
|The other common option is the '''-r''' option. Let us see where this options are useful?
  
 
|-
 
|-
| 17:07
+
| 16:52
 
|Let us switch back to the terminal.
 
|Let us switch back to the terminal.
  
 
|-
 
|-
| 17:12
+
| 16:57
|rm command is not normally used for deleting directories, for that we have the rmdir command.
+
|'''rm''' command is not normally used for deleting directories, for that we have the rmdir command.
  
 
|-
 
|-
| 17:21
+
| 17:05
|But rmdir command normally deletes a directory only then it is empty.  
+
|But '''rmdir''' command normally deletes a directory only then it is empty.  
  
 
|-
 
|-
| 17:27
+
| 17:12
 
|What if we want to delete a directory that has a number of files and subdirectories inside.  
 
|What if we want to delete a directory that has a number of files and subdirectories inside.  
  
 
|-
 
|-
| 17:35
+
| 17:19
|Let us try the rm command to do this.
+
|Let us try the '''rm''' command to do this.
  
 
|-
 
|-
| 17:38
+
| 17:23
|Let us type rm and the directory that we want to delete which is testdir and press enter.
+
|Let us type '''rm''' and the directory that we want to delete which is '''testdir''' and press enter.
  
 
|-
 
|-
| 17:47
+
| 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.
  
 
|-
 
|-
| 17:55
+
| 17:39
 
|But if we combine the -r and -f option then we can do this.
 
|But if we combine the -r and -f option then we can do this.
  
 
|-
 
|-
| 18:03
+
| 17:47
|Press rm -rf testdir and then press enter.
+
|Press ''' rm -rf testdir''' and then press enter.
  
 
|-
 
|-
| 18:16
+
| 18:00
|Now the testdir directory has been successfully deleted.
+
|Now the '''testdir''' directory has been successfully deleted.
  
 
|-
 
|-
| 18:22
+
| 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.
  
 
|-
 
|-
| 18:27
+
| 18:11
|The cmp command.
+
|The '''cmp''' command.
  
 
|-
 
|-
| 18:29
+
| 18:13
 
|Sometimes we need to check whether two files are same. If they are same then we may delete one of them.
 
|Sometimes we need to check whether two files are same. If they are same then we may delete one of them.
  
 
|-
 
|-
| 18:37
+
| 18:22
 
|Also we may want to see whether a file has changed since the last version.  
 
|Also we may want to see whether a file has changed since the last version.  
  
 
|-
 
|-
| 18:44
+
| 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.
  
 
|-
 
|-
| 18:49
+
| 18:33
 
|It compares two files byte by byte.
 
|It compares two files byte by byte.
  
 
|-
 
|-
| 18:54
+
| 18:38
|To compare file1 and file2 we would write cmp file1 file2.
+
|To compare file1 and file2 we would write '''cmp file1 file2.'''
  
 
|-
 
|-
| 19:03
+
| 18: 47
 
|If the two files have exactly same content then no message would be shown.
 
|If the two files have exactly same content then no message would be shown.
  
 
|-
 
|-
| 19:11
+
| 18:55
 
|Only the prompt will be printed.  
 
|Only the prompt will be printed.  
  
 
|-
 
|-
| 19:14
+
| 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.  
  
 
|-
 
|-
| 19:25
+
| 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.
  
 
|-
 
|-
| 19:35
+
| 19:19
 
|Let us see what they contain?
 
|Let us see what they contain?
  
 
|-
 
|-
| 19:38
+
| 19:22
|Type cat sample1 and press enter.It contains
+
|Type '''cat sample1''' and press enter. It contains the text '''This is a Linux file to test the cmp command'''
the text “This is a Linux file to test the cmp command”
+
  
 
|-
 
|-
| 19:50
+
| 19:34
|The other file sample2 will contain the text and to see that we will type cat sample2 and press enter.
+
|The other file '''sample2''' will contain the text and to see that we will type '''cat sample2''' and press enter.
  
 
|-
 
|-
| 20:00
+
| 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.'''
  
 
|-
 
|-
| 20:06
+
| 19:50
|Now we would apply the cmp command on this two files.
+
|Now we would apply the '''cmp''' command on this two files.
  
 
|-
 
|-
| 20:11
+
| 19:55
|We will write cmp sample1 sample2 and press enter.
+
|We will write '''cmp space sample1 space sample2''' and press enter.
  
 
|-
 
|-
| 20:23
+
| 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.  
  
 
|-
 
|-
| 20:32
+
| 20:16
 
|Let us clear the screen before moving ahead to the next command.
 
|Let us clear the screen before moving ahead to the next command.
  
 
|-
 
|-
| 20:38
+
| 20:22
|The next command we will see is the wc command.
+
|The next command we will see is the '''wc''' command.
  
 
|-
 
|-
| 20:43
+
| 20:26
 
|This command is used to count the number of characters, words and lines in a file.
 
|This command is used to count the number of characters, words and lines in a file.
  
 
|-
 
|-
| 20:50
+
| 20:34
|We have a file named sample3 in our home directory.
+
|We have a file named '''sample3''' in our home directory.
  
 
|-
 
|-
| 20:56
+
| 20:39
|Let us see its content, for that we will type cat sample3 and press enter.
+
|Let us see its content, for that we will type '''cat space sample3''' and press enter.
  
 
|-
 
|-
| 21:05
+
| 20:50
|This is the content of sample3.
+
|This is the content of '''sample3.'''
  
 
|-
 
|-
| 21:10
+
| 20:54
 
|Now let us use the wc command on this file.
 
|Now let us use the wc command on this file.
 
  
 
|-
 
|-
| 21:14
+
| 20:59
|For that we would write wc sample3 and press enter.
+
|For that we would write '''wc sample3''' and press enter.
  
 
|-
 
|-
| 21:25
+
| 21:10
|The command points out that the file has 6 lines, 67 words and 385 characters.
+
|These command points out that the file has 6 lines, 67 words and 385 characters.
  
 
|-
 
|-
| 21:38
+
| 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.
  
 
|-
 
|-
| 21:43
+
| 21:27
 
|There are many more commands. Moreover each of the command that we saw has many other options.  
 
|There are many more commands. Moreover each of the command that we saw has many other options.  
  
 
|-
 
|-
| 21:51
+
| 21:36
|I encourage you to see more about them using the man command.
+
|I encourage you to see more about them using the '''man''' command.
  
 
|-
 
|-
| 22:00
+
| 21:44
 
|This brings me to the end of this tutorial at last.
 
|This brings me to the end of this tutorial at last.
  
 
|-
 
|-
| 22:04
+
| 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.  
 
| 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.  
  
 
|-
 
|-
| 22:17
+
| 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.  
  
 
|-
 
|-
| 22:34
+
| 22:18
 
|This is Anirban signing off . Thanks for joining.
 
|This is Anirban signing off . Thanks for joining.

Revision as of 14:04, 4 December 2014

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 [OPTION]... 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 [OPTION]...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 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 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 a head 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 a head 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 You see that this 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 will 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 a some content directly with '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 exist 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 exiting 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 rename 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 there 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 this 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 this files abc1 and abc2.
15:09 For this we would type rm space testdir/abc1 space testdir/abc2 and press enter.
15:31 This remove 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 do delete a single file we write rm and than 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 options 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 then it is empty.
17:12 What if we want to delete a directory that has a number of files and subdirectories 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 this 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 content, 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 These 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