Difference between revisions of "BOSS-Linux/C2/File-System/English-timed"

From Script | Spoken-Tutorial
Jump to: navigation, search
(Created page with "{| border=1 |'''Time''' |'''Narration''' |- | 00:00 |Welcome to this spoken tutorial on Linux File System. |- | 00:04 |I am using Linux Operating system. |- | 00:08 |We assume...")
 
Line 7: Line 7:
 
|-
 
|-
 
| 00:04
 
| 00:04
−
|I am using Linux Operating system.
+
|I am using Ubuntu 10.04.  
 
|-
 
|-
−
| 00:08
+
| 00:07
 
|We assume that you know how to get started with the Linux operating system and have some basic idea about commands.  
 
|We assume that you know how to get started with the Linux operating system and have some basic idea about commands.  
 
|-
 
|-
−
| 00:16
+
| 00:13
 
|If you are interested, it is available through another spoken tutorial, on the following website http://spoken-tutorial.org
 
|If you are interested, it is available through another spoken tutorial, on the following website http://spoken-tutorial.org
 
|-
 
|-
−
| 00:28
+
| 00:25
 
|Also note that linux is case sensitive.
 
|Also note that linux is case sensitive.
 
|-
 
|-
−
| 00:32
+
| 00:28
 
| All the commands used in this tutorial are in lower case unless otherwise mentioned.  
 
| All the commands used in this tutorial are in lower case unless otherwise mentioned.  
 
|-
 
|-
−
| 00:41
+
| 00:36
 
|In Linux almost everything is a file.  
 
|In Linux almost everything is a file.  
 
|-
 
|-
−
| 00:44
+
| 00:39
 
|So what is a file? In real life we know that a file is where we store our documents and papers.  
 
|So what is a file? In real life we know that a file is where we store our documents and papers.  
 
|-
 
|-
−
| 00:54
+
| 00:47
 
|Similarly in Linux a file is a container for storing information.  
 
|Similarly in Linux a file is a container for storing information.  
 
|-
 
|-
−
| 01:00
+
| 00:53
 
|Next what is a directory?  
 
|Next what is a directory?  
 
|-
 
|-
−
| 01:03
+
| 00:56
 
|A directory can be understood as a collection of files and other (sub)directories.
 
|A directory can be understood as a collection of files and other (sub)directories.
 
|-
 
|-
−
| 01:10
+
| 01:02
 
|A directory helps us in organising our files in a systematic manner.  
 
|A directory helps us in organising our files in a systematic manner.  
 
|-
 
|-
−
| 01:16
+
| 01:08
 
|This is like what we call folders in Windows.
 
|This is like what we call folders in Windows.
 
|-
 
|-
−
| 01:20
+
| 01:12
 
| It allows different users to have their own directories with their files which others cannot access or modify.  
 
| It allows different users to have their own directories with their files which others cannot access or modify.  
 
|-
 
|-
−
| 01:30
+
| 01:20
 
|Also if there are no directories, all the files on the system need to have unique names,which would be very difficult to maintain.
 
|Also if there are no directories, all the files on the system need to have unique names,which would be very difficult to maintain.
 
|-
 
|-
−
| 01:41
+
| 01:31
−
|These definitions of files and directories are good to get a general feel about them, they are not entirely accurate.  
+
|Though these definitions of files and directories are good to get a general feel about them, they are not entirely accurate.  
 
|-
 
|-
−
| 01:51
+
| 01:42
 
|As well as its contents, a file has a name and some properties, or “administrative information”; that is, the file’s creation/modification date and its permissions.  
 
|As well as its contents, a file has a name and some properties, or “administrative information”; that is, the file’s creation/modification date and its permissions.  
 
|-
 
|-
−
| 02:05
+
| 01:55
−
|Thus  properties are stored in the file’s inode, a special block of data in the file system that also contains the length of the file and where on the disk it’s stored.  
+
|The properties are stored in the file’s inode, a special block of data in the file system that also contains the length of the file and where on the disk it’s stored.  
 
|-
 
|-
−
| 02:20
+
| 02:08
−
|The system uses the number of the file’s '''inode''' ; the directory structure just names the file for our benefit as its easier for us to remember names than larger numbers.
+
|The system uses the number of the file’s inode; the directory structure just names the file for our benefit as its easier for us to remember names than large numbers.
 
|-
 
|-
−
|02:35
+
|02:23
 
|Contrary to its oversimplified definition, a directory doesnot actually store other files ,it is itself a file that holds the inode numbers and names of other files.  
 
|Contrary to its oversimplified definition, a directory doesnot actually store other files ,it is itself a file that holds the inode numbers and names of other files.  
 
|-
 
|-
−
| 02:49
+
| 02:37
 
|In fact in Linux there are three kinds of files:
 
|In fact in Linux there are three kinds of files:
 
|-
 
|-
−
| 02:54
+
| 02:41
−
|Regular Files or Ordinary files: It contains only data , as a stream of characters.
+
|1 Regular Files or Ordinary files: It contains only data , as a stream of characters.
 
|-
 
|-
−
| 03:01
+
| 02:48
−
|Directories: As we just saw in the previous slides.
+
|2 Directories: As we just saw in the previous slides.
 
|-
 
|-
−
| 03:07
+
| 02:52
−
|Device Files: All hardware devices and peripherals are represented as files in Linux.  
+
|3 Device Files: All hardware devices and peripherals are represented as files in Linux.  
 
|-
 
|-
−
| 03:14
+
| 02:59
 
|A CD, a Harddisk or even an usb stick, everything is a file in Linux. But why is this so? This helps to read and write these devices in a way similar to that for ordinary files.
 
|A CD, a Harddisk or even an usb stick, everything is a file in Linux. But why is this so? This helps to read and write these devices in a way similar to that for ordinary files.
 
|-
 
|-
−
| 03:32
+
| 03:15
 
|All files in Linux are related, in short all form a family much like we do.  
 
|All files in Linux are related, in short all form a family much like we do.  
 
|-
 
|-
−
| 03:39
+
| 03:22
 
|A directory containing say some files and subdirectories will have a parent – child relationship with each other. This gives rise to the Linux File System Tree.
 
|A directory containing say some files and subdirectories will have a parent – child relationship with each other. This gives rise to the Linux File System Tree.
 
|-
 
|-
−
| 03:52
+
| 03:34
 
|At the top is the root( denoted by a frontslash /). It contains all the other files and directories.  
 
|At the top is the root( denoted by a frontslash /). It contains all the other files and directories.  
 
|-
 
|-
−
| 04:04
+
| 03:42
 
|This also helps in easy navigation from one file or directory to other, if we know the correct path.  
 
|This also helps in easy navigation from one file or directory to other, if we know the correct path.  
 
|-
 
|-
−
| 04:12
+
| 03:51
 
|As we work with a Linux file system, it seems that we are moving along this tree.  
 
|As we work with a Linux file system, it seems that we are moving along this tree.  
 
|-
 
|-
−
| 04:18
+
| 03:56
 
|One command and there you are teleported from one place to other.
 
|One command and there you are teleported from one place to other.
 
|-
 
|-
−
| 04:24
+
| 04:01
 
|Sounds interesting!! Indeed it is. As we will see.
 
|Sounds interesting!! Indeed it is. As we will see.
 
|-
 
|-
−
| 04:29
+
| 04:05
 
|When we login into the Linux system we are by default in a home directory.  
 
|When we login into the Linux system we are by default in a home directory.  
 
|-
 
|-
−
| 04:36
+
| 04:11
 
|Now Switch to the terminal.
 
|Now Switch to the terminal.
−
 
 
|-
 
|-
−
| 04:39
+
| 04:13
−
|To see the home directory , Type at the command prompt "'echo space dollar H-O-M-E in capital"' and press enter.
+
| Ctrl+alt+T helps to start a terminal in Ubuntu.
 +
|-
 +
| 04:17
 +
|This command may not work in all unix systems, however. A general procedure to open a terminal is already explained in another spoken tutorial.
 +
|-
 +
| 04:27
 +
|To see the home directory , Type at the command prompt
 +
"echo space dollar H-O-M-E in capital" and press enter.
 
|-
 
|-
−
| 04:53
+
| 04:40
−
|This gives the pathname of our '''home''' directory.  
+
|This gives the pathname of our home directory.  
 
|-
 
|-
−
| 04:57
+
| 04:44
 
|We can move around from one directory to other.  
 
|We can move around from one directory to other.  
 
|-
 
|-
−
| 05:01
+
| 04:47
−
|But any time we can be in one directory and this directory is known as the current directory or working directory.  
+
|But any time we can be in one directory and this directory is known as the current directory or working directory. Now go back to slides.
 
|-
 
|-
−
| 05:09
+
| 04:56
−
|The '''pwd''' command helps us to see the current directory. '''pwd''' stands for present working directory.
+
|The pwd command helps us to see the current directory. pwd stands for present working directory.
 
|-
 
|-
−
| 05:18
+
| 05:03
−
|Type at the command prompt '"pwd'" and press enter. Now this is our present working directory.  
+
|Type at the command prompt "pwd" and press enter. Now this is our present working directory.  
 
|-
 
|-
−
| 05:28
+
| 05:13
 
|We have said that we can move from one directory to other.  
 
|We have said that we can move from one directory to other.  
 
|-
 
|-
−
| 05:32
+
| 05:17
−
|But how do we do so? We have the '''cd''' command for this purpose.
+
|But how do we do so? We have the cd command for this purpose.
 
|-
 
|-
−
| 05:39
+
| 05:22
−
|You have to type the command '''cd''' followed by the pathname of the directory you want to move to.
+
|You have to type the command cd followed by the pathname of the directory you want to move to.
 
|-
 
|-
−
| 05:47
+
| 05:28
−
|Lets again see our current directory by typing '''pwd''' at the command prompt and press enter.
+
|Lets again see our current directory by typing pwd at the command prompt and press enter.
 
|-
 
|-
−
|05:57
+
|05:37
 
| So, now we are placed in this directory.
 
| So, now we are placed in this directory.
 
|-
 
|-
−
| 06:01
+
| 05:41
−
|Now say we want to move to '''slash usr''' directory. So, type "'cd space slash usr'" . Remember here slash in linux means front slash and press enter.
+
|Now say we want to move to slash usr directory. So, type  
 +
"cd space slash usr" . Remember here slash in linux means front slash and press enter.
 
|-
 
|-
−
| 06:17
+
| 05:56
−
|Now lets see our current directory. Type '''pwd''' and press enter.
+
|Now lets see our current directory. Type pwd and press enter.
 
|-
 
|-
−
| 06:24
+
| 06:03
−
|Yes we have moved to '''slash usr''' directory.  
+
|Yes we have moved to slash usr directory.  
 
|-
 
|-
−
| 06:30
+
| 06:08
 
|The problem here is the pathnames can be very long, this is because these are Absolute Pathnames that enlist the entire path staring from the root directory.
 
|The problem here is the pathnames can be very long, this is because these are Absolute Pathnames that enlist the entire path staring from the root directory.
 
|-
 
|-
−
| 06:42
+
| 06:18
 
|Instead we may use Relative pathnames that begin from the current directory.  
 
|Instead we may use Relative pathnames that begin from the current directory.  
 
|-
 
|-
−
| 06:48
+
| 06:23
−
|Here we need to know two special characters. '''dot''' that represent the current directory and '''dot dot''' that represent the '''parent directory''' of the current directory.  
+
|Here we need to know two special characters.
 +
'''dot''' that represent the current directory and '''dot dot''' that represent the parent directory of the current directory.  
 
|-
 
|-
−
| 07:02
+
| 06:36
−
|Now let us have a brief session on '''cd''' command
+
|Now let us have a brief session on cd command
 
|-
 
|-
−
| 07:06
+
| 06:40
−
|The command '''cd''' without any argument is used to move back that to the home directory.  
+
|The command cd without any argument is used to move back to the home directory.  
 
|-
 
|-
−
| 07:13
+
| 06:46
−
|Type at the command prompt "'cd'" and press enter.  
+
|Type at the command prompt "cd" and press enter.  
 
|-
 
|-
−
| 07:19
+
| 06:51
−
|Now check our current directory by the '''pwd''' command.  
+
|Now check our current directory by the pwd command.  
 
|-
 
|-
−
| 07:23
+
| 06:55
−
|So, now we are back in our home directory '''/home/gnuhata''' [ slash home slash gnuhata ]  
+
|So, now we are back in our home directory
−
 
+
<nowiki>/home/gnuhata [ narration- slash home slash gnuhata ] </nowiki>
 
|-
 
|-
−
| 07:30
+
| 07:01
−
|Now let us move to music directory. Type at the command prompt "'cd space Music(M in capital) slash"' and press enter
+
|Now let us move to music directory. Type at the command prompt "cd space Music(M in capital) slash" and press enter
 
|-
 
|-
−
| 07:43
+
| 07:13
−
|Now check our current directory by the '''pwd''' command. '''pwd''' and press enter. See, we have moved ''' /home/gnuhata/Music '''
+
|Now check our current directory by the pwd command. pwd and press enter. See, we have moved /home/gnuhata/Music  
 
|-
 
|-
−
| 07:57
+
| 07:26
−
|Let us go to the parent directory of Music. For that you have to use cd command with dot dot.  
+
|Let us go to the parent directory from Music. For that you have to use cd command with dot dot.  
 
|-
 
|-
−
| 08:04
+
| 07:33
−
|Type at the command prompt '''cd space dot dot''' and press enter.  
+
|Type at the command prompt cd space dot dot and press enter.  
 
|-
 
|-
−
| 08:11
+
| 07:40
−
|Now check our present directory by typing '''pwd.''' We are again in '''/home/gnuhata'''
+
|Now check our present directory by typing pwd. We are again in /home/gnuhata
 
|-
 
|-
−
| 08:23
+
| 07:51
 
|Now lets try to move to a subdirectory of the current directory using dot.  
 
|Now lets try to move to a subdirectory of the current directory using dot.  
 
|-
 
|-
−
| 08:30
+
| 07:58
−
|Type at the command prompt '''cd space dot slash Documents(D in capital) slash'''. Press enter.
+
|Type at the command prompt cd space dot slash Documents(D in capital) slash. Press enter.
 
|-
 
|-
−
| 08:42
+
| 08:09
−
|Check our current directory by typing '''pwd.''' We are at ''' /home/gnuhata/Documents'''
+
|Check our current directory by typing pwd. We are at /home/gnuhata/Documents
 
|-
 
|-
−
| 08:53
+
| 08:19
 
|Let me clear the screen by pressing control L. So you can see clearly.
 
|Let me clear the screen by pressing control L. So you can see clearly.
 
|-
 
|-
−
| 08:58
+
| 08:23
−
|To go back to our home directory by '''cd''' command. Type '''cd''' and press enter.
+
|To go back to our home directory by cd command.
 +
Type cd and press enter.
 
|-
 
|-
−
| 09:07
+
| 08:32
−
|Again check our current directory by '''pwd''' command. We are back to '''/home/gnuhata''' .  
+
|Again check our current directory by pwd command. We are back to /home/gnuhata .  
 
|-
 
|-
−
| 09:17
+
| 08:41
−
|We can combine any number of dot dot separated by slash in a relative path .  
+
|<nowiki>We can combine any number of .. [narration - dot dot] separated by / [narration- slash] in a relative path . </nowiki>
 
|-
 
|-
−
| 09:23
+
| 08:47
−
|In this slide, we can see the file system hierarchy. '''Root''' or '''slash''' is at the top. '''home''' and '''bin''' are two sub-directories under '''root'''. '''username''' , here the directory named gnuhata is a sub-directory under '''home.'''
+
|In this slide, we can see the file system hierarchy. Root or / is at the top. home and bin are two sub-directories under root. username , here the directory named gnuhata is a sub-directory under home.
 
|-
 
|-
−
| 09:43
+
| 09:05
−
| So, now we are in '''/home/gnuhata.''' Now how can we go to the bin directory?  
+
| So, now we are in /home/gnuhata. Now how can we go to the bin directory?  
 
|-
 
|-
−
| 09:51
+
| 09:12
−
|Type at the command prompt "'cd space dot dot slash dot dot slash bin'" and press enter.  
+
|Type at the command prompt
−
 
+
"cd space dot dot slash dot dot slash bin" and press enter.  
 
|-
 
|-
−
| 10:03
+
| 09:23
−
|Check our current directory by the command '''pwd.'''  We are at /bin (slash bin)
+
|Check our current directory by the command pwd.  
−
 
+
<nowiki>We are at /bin [narration - slash bin] </nowiki>
 
|-
 
|-
−
| 10:11
+
| 09:30
−
|The first .. (dot dot) takes us from /home/gnuhata (slash home slash gnuhata) to /home (slash home)
+
|<nowiki>The first .. [narration-dot dot] takes us from /home/gnuhata [narration - slash home slash gnuhata] to /home [narration - slash home].</nowiki>
  
 
|-
 
|-
−
| 10:18
+
| 09:37
−
|The next takes us from '''slash home''' to root.  
+
|<nowiki>The next takes us from /home to </nowiki>root.  
 
|-
 
|-
−
| 10:24
+
| 09:43
−
|Now from root or slash, we have moved to /bin directory.
+
|Now from / or root, we have moved to /bin directory.
 
|-
 
|-
−
| 10:30
+
| 09:48
−
|Go back to our home directory by the command '''cd.'''
+
|Go back to our home directory by the command cd.  
 
|-
 
|-
−
| 10:34
+
| 09:52
−
|To create a directory we use the '''mkdir''' command.  
+
|To create a directory we use the mkdir command.  
  
 
|-
 
|-
−
| 10:40
+
| 09:56
 
|You have to type the command and name of directory to be created and a directory would be created under the current directory.
 
|You have to type the command and name of directory to be created and a directory would be created under the current directory.
 
|-
 
|-
−
| 10:49
+
| 10:04
−
|To create a directory named '''testdir''', type the command '"mkdir space testdir'" and press enter.
+
|To create a directory named testdir, type the command "mkdir space testdir" and press enter.
 
|-
 
|-
−
| 11:01
+
| 10:15
−
|This creates the '''testdir''' directory successfully.  
+
|This creates the testdir directory successfully.  
 
|-
 
|-
−
| 11:05
+
| 10:19
 
|Note that, there is no explicit notification of successful directory creation or removal.
 
|Note that, there is no explicit notification of successful directory creation or removal.
 
|-
 
|-
−
| 11:13
+
| 10:25
 
| If you do not get any error message, it denotes successful execution.  
 
| If you do not get any error message, it denotes successful execution.  
 
|-
 
|-
−
| 11:18
+
| 10:30
 
|We can also use the relative or absolute pathname to create a directory anywhere in the tree provided we have the permission to do so and a directory by that name does not already exist.
 
|We can also use the relative or absolute pathname to create a directory anywhere in the tree provided we have the permission to do so and a directory by that name does not already exist.
 
|-
 
|-
−
| 11:33
+
| 10:43
 
|This process can be used for making multiple directories or even a hierarchy of directories.
 
|This process can be used for making multiple directories or even a hierarchy of directories.
 
|-
 
|-
−
| 11:39
+
| 10:49
−
|Type "'mkdir space test1 space test2''' and press enter ,this will make two directories named '''test1''' and '''test2''' under the present directory.
+
|Type "mkdir space test1 space test2 and press enter ,this will make two directories named test1 and test2 under the present directory.
 
|-
 
|-
−
| 11:57
+
| 11:06
−
|Type "'mkdir space testtree space testtree slash test3'".  
+
|Type "mkdir space testtree space testtree slash test3".  
 
|-
 
|-
−
| 12:11
+
| 11:20
−
|This will make a directory '''testtree''' and another directory '''test3''' which is a sub-directory under '''testtree.'''
+
|This will make a directory testtree and another directory test3 which is a sub-directory under testtree.  
 
|-
 
|-
−
| 12:20
+
| 11:28
−
|So, we have created four directories namely '''testdir,test1,test2 '''and '''testtree''' in the current directory, out of which first three are empty and the last one contains a subdirectory namely test3.  
+
|So, we have created four directories namely testdir,test1,test2 and testtree in the current directory, out of which first three are empty and the last one contains a subdirectory namely test3.  
 
|-
 
|-
−
| 12:40
+
| 11:47
−
|Similar to the '''mkdir''' is the '''rmdir''' command which is used for removing a directory or directories.
+
|Similar to mkdir is the rmdir command which is used for removing a directory or directories.
 
|-
 
|-
−
| 12:50
+
| 11:56
−
|The command "'rmdir space test1'" removes the '''test1''' directory successfully.  
+
|The command "rmdir space test1" removes the test1 directory successfully.  
 
|-
 
|-
−
| 13:00
+
| 12:09
 
|A directory can be removed only if you are its owner, your current directory is hierarchically above the directory to be removed and the directory is empty.
 
|A directory can be removed only if you are its owner, your current directory is hierarchically above the directory to be removed and the directory is empty.
 
|-
 
|-
−
| 13:13
+
| 12:23
−
|Now type at the command prompt '"cd space testtree slash test3"'
+
|Now type at the command prompt
 +
"cd space testtree slash test3"
 
|-
 
|-
−
| 13:25
+
| 12:35
−
|So, we are now in '''test3''' directory which is a subdirectory under '''testtree.'''
+
|So, we are now in test3 directory which is a subdirectory under testtree.
 
|-
 
|-
−
| 13:33
+
| 12:42
−
|Lets try to remove the '''testdir''' directory by typing the command '"rmdir space testdir'". Press enter.  
+
|Lets try to remove the testdir directory by typing the command "rmdir space testdir". Press enter.  
 
|-
 
|-
−
| 13:46
+
| 12:55
 
|We see it can't be done, because the current directory is not hierarchically above the directory to be removed.
 
|We see it can't be done, because the current directory is not hierarchically above the directory to be removed.
 
|-
 
|-
−
| 13:54
+
| 13:02
−
|So,we have to go to the directory which is hierarchically above '''testdir''' directory.  
+
|So,we have to go to the directory which is hierarchically above testdir directory.  
 
|-
 
|-
−
| 14:00
+
| 13:08
−
|Type "'cd space dot dot"' and press enter.  
+
|Type "cd space dot dot" and press enter.  
 
|-
 
|-
−
| 14:06
+
| 13:14
−
|Now, go back to our parent directory by typing the command "'cd space dot dot'".  
+
|Now, go back to our parent directory by typing the command "cd space dot dot".  
 
|-
 
|-
−
| 14:13
+
| 13:20
 
|Now, again try the previous command.  
 
|Now, again try the previous command.  
 
|-
 
|-
−
| 14:16
+
| 13:24
 
|Type "rmdir space testdir". Press enter.  
 
|Type "rmdir space testdir". Press enter.  
 
|-
 
|-
−
| 14:23
+
| 13:30
−
|The '''testdir''' directory is successfully deleted. Note that, '''testdir''' directory was also empty.
+
|The testdir directory is successfully deleted. Note that, testdir directory was also empty.
 
|-
 
|-
−
| 14:32
+
| 13:38
−
|Multiple directories or a hierarchy of directories can be removed at once.So, try to delete the '''testtree''' directory along with its subdirectory '''test3.'''
+
|Multiple directories or a hierarchy of directories can be removed at once.So, try to delete the testtree directory along with its subdirectory test3.  
 
|-
 
|-
−
| 14:43
+
| 13:48
−
|Type at the command prompt '"rmdir space testtree space testtree slash test3'" press enter.
+
|Type at the command prompt
 +
"rmdir space testtree space testtree slash test3 "press enter.
 
|-
 
|-
−
| 14:57
+
| 14:02
−
|See, it is giving the error message that '''testree''' directory cannot be removed because testtree is not empty.  
+
|See, it is giving the error message that 'testree' directory cannot be removed because testtree is not empty.  
 
|-
 
|-
−
| 15:07
+
| 14:11
−
|But one thing which you may miss is that '''testtree slash test3''' has been deleted as it was empty.  
+
|But one thing which you may miss is that testtree/test3 has been deleted as it was empty.  
 
|-
 
|-
−
| 15:16
+
| 14:19
−
|To check that, type at the command prompt "'cd space testtree"' and press enter.
+
|To check that, type at the command prompt "cd space testtree" and press enter.
 
|-
 
|-
−
| 15:25
+
| 14:27
−
|Now type "'ls'" and press enter. See, the directory contains nothing. So, '''test3''' was deleted.
+
|Now type "ls" and press enter. See, the directory contains nothing. So, test3 was deleted.
 
|-
 
|-
−
| 15:34
+
| 14:36
 
|So in this linux tutorial we have learnt about Linux Files and directories and how to work with Linux Directories. See them, move between them, make them,remove them.  
 
|So in this linux tutorial we have learnt about Linux Files and directories and how to work with Linux Directories. See them, move between them, make them,remove them.  
 
|-
 
|-
−
| 15:48
+
| 14:49
 
|This brings me to the end of this tutorial. Spoken Tutorials are a part of the Talk to a Teacher project, supported by the National Mission on Education through ICT.
 
|This brings me to the end of this tutorial. Spoken Tutorials are a part of the Talk to a Teacher project, supported by the National Mission on Education through ICT.
 
|-
 
|-
−
| 16:02
+
| 15:03
 
|More information this is available at the following link  
 
|More information this is available at the following link  
 
|-
 
|-
−
| 16:08
+
| 15:08
−
|This is Anusha Kadambala signing off. Thanks for joining.
+
|This script has been contributed by ----------------------(name of the translator) and this is -----------------------(name of the recorder) from --------------------------(name of the place)signing off . Thanks for joining.
  
 
|}
 
|}

Revision as of 12:50, 4 December 2014

Time Narration
00:00 Welcome to this spoken tutorial on Linux File System.
00:04 I am using Ubuntu 10.04.
00:07 We assume that you know how to get started with the Linux operating system and have some basic idea about commands.
00:13 If you are interested, it is available through another spoken tutorial, on the following website http://spoken-tutorial.org
00:25 Also note that linux is case sensitive.
00:28 All the commands used in this tutorial are in lower case unless otherwise mentioned.
00:36 In Linux almost everything is a file.
00:39 So what is a file? In real life we know that a file is where we store our documents and papers.
00:47 Similarly in Linux a file is a container for storing information.
00:53 Next what is a directory?
00:56 A directory can be understood as a collection of files and other (sub)directories.
01:02 A directory helps us in organising our files in a systematic manner.
01:08 This is like what we call folders in Windows.
01:12 It allows different users to have their own directories with their files which others cannot access or modify.
01:20 Also if there are no directories, all the files on the system need to have unique names,which would be very difficult to maintain.
01:31 Though these definitions of files and directories are good to get a general feel about them, they are not entirely accurate.
01:42 As well as its contents, a file has a name and some properties, or “administrative information”; that is, the file’s creation/modification date and its permissions.
01:55 The properties are stored in the file’s inode, a special block of data in the file system that also contains the length of the file and where on the disk it’s stored.
02:08 The system uses the number of the file’s inode; the directory structure just names the file for our benefit as its easier for us to remember names than large numbers.
02:23 Contrary to its oversimplified definition, a directory doesnot actually store other files ,it is itself a file that holds the inode numbers and names of other files.
02:37 In fact in Linux there are three kinds of files:
02:41 1 Regular Files or Ordinary files: It contains only data , as a stream of characters.
02:48 2 Directories: As we just saw in the previous slides.
02:52 3 Device Files: All hardware devices and peripherals are represented as files in Linux.
02:59 A CD, a Harddisk or even an usb stick, everything is a file in Linux. But why is this so? This helps to read and write these devices in a way similar to that for ordinary files.
03:15 All files in Linux are related, in short all form a family much like we do.
03:22 A directory containing say some files and subdirectories will have a parent – child relationship with each other. This gives rise to the Linux File System Tree.
03:34 At the top is the root( denoted by a frontslash /). It contains all the other files and directories.
03:42 This also helps in easy navigation from one file or directory to other, if we know the correct path.
03:51 As we work with a Linux file system, it seems that we are moving along this tree.
03:56 One command and there you are teleported from one place to other.
04:01 Sounds interesting!! Indeed it is. As we will see.
04:05 When we login into the Linux system we are by default in a home directory.
04:11 Now Switch to the terminal.
04:13 Ctrl+alt+T helps to start a terminal in Ubuntu.
04:17 This command may not work in all unix systems, however. A general procedure to open a terminal is already explained in another spoken tutorial.
04:27 To see the home directory , Type at the command prompt

"echo space dollar H-O-M-E in capital" and press enter.

04:40 This gives the pathname of our home directory.
04:44 We can move around from one directory to other.
04:47 But any time we can be in one directory and this directory is known as the current directory or working directory. Now go back to slides.
04:56 The pwd command helps us to see the current directory. pwd stands for present working directory.
05:03 Type at the command prompt "pwd" and press enter. Now this is our present working directory.
05:13 We have said that we can move from one directory to other.
05:17 But how do we do so? We have the cd command for this purpose.
05:22 You have to type the command cd followed by the pathname of the directory you want to move to.
05:28 Lets again see our current directory by typing pwd at the command prompt and press enter.
05:37 So, now we are placed in this directory.
05:41 Now say we want to move to slash usr directory. So, type

"cd space slash usr" . Remember here slash in linux means front slash and press enter.

05:56 Now lets see our current directory. Type pwd and press enter.
06:03 Yes we have moved to slash usr directory.
06:08 The problem here is the pathnames can be very long, this is because these are Absolute Pathnames that enlist the entire path staring from the root directory.
06:18 Instead we may use Relative pathnames that begin from the current directory.
06:23 Here we need to know two special characters.

dot that represent the current directory and dot dot that represent the parent directory of the current directory.

06:36 Now let us have a brief session on cd command
06:40 The command cd without any argument is used to move back to the home directory.
06:46 Type at the command prompt "cd" and press enter.
06:51 Now check our current directory by the pwd command.
06:55 So, now we are back in our home directory

/home/gnuhata [ narration- slash home slash gnuhata ]

07:01 Now let us move to music directory. Type at the command prompt "cd space Music(M in capital) slash" and press enter
07:13 Now check our current directory by the pwd command. pwd and press enter. See, we have moved /home/gnuhata/Music
07:26 Let us go to the parent directory from Music. For that you have to use cd command with dot dot.
07:33 Type at the command prompt cd space dot dot and press enter.
07:40 Now check our present directory by typing pwd. We are again in /home/gnuhata
07:51 Now lets try to move to a subdirectory of the current directory using dot.
07:58 Type at the command prompt cd space dot slash Documents(D in capital) slash. Press enter.
08:09 Check our current directory by typing pwd. We are at /home/gnuhata/Documents
08:19 Let me clear the screen by pressing control L. So you can see clearly.
08:23 To go back to our home directory by cd command.

Type cd and press enter.

08:32 Again check our current directory by pwd command. We are back to /home/gnuhata .
08:41 We can combine any number of .. [narration - dot dot] separated by / [narration- slash] in a relative path .
08:47 In this slide, we can see the file system hierarchy. Root or / is at the top. home and bin are two sub-directories under root. username , here the directory named gnuhata is a sub-directory under home.
09:05 So, now we are in /home/gnuhata. Now how can we go to the bin directory?
09:12 Type at the command prompt

"cd space dot dot slash dot dot slash bin" and press enter.

09:23 Check our current directory by the command pwd.

We are at /bin [narration - slash bin]

09:30 The first .. [narration-dot dot] takes us from /home/gnuhata [narration - slash home slash gnuhata] to /home [narration - slash home].
09:37 The next takes us from /home to root.
09:43 Now from / or root, we have moved to /bin directory.
09:48 Go back to our home directory by the command cd.
09:52 To create a directory we use the mkdir command.
09:56 You have to type the command and name of directory to be created and a directory would be created under the current directory.
10:04 To create a directory named testdir, type the command "mkdir space testdir" and press enter.
10:15 This creates the testdir directory successfully.
10:19 Note that, there is no explicit notification of successful directory creation or removal.
10:25 If you do not get any error message, it denotes successful execution.
10:30 We can also use the relative or absolute pathname to create a directory anywhere in the tree provided we have the permission to do so and a directory by that name does not already exist.
10:43 This process can be used for making multiple directories or even a hierarchy of directories.
10:49 Type "mkdir space test1 space test2 and press enter ,this will make two directories named test1 and test2 under the present directory.
11:06 Type "mkdir space testtree space testtree slash test3".
11:20 This will make a directory testtree and another directory test3 which is a sub-directory under testtree.
11:28 So, we have created four directories namely testdir,test1,test2 and testtree in the current directory, out of which first three are empty and the last one contains a subdirectory namely test3.
11:47 Similar to mkdir is the rmdir command which is used for removing a directory or directories.
11:56 The command "rmdir space test1" removes the test1 directory successfully.
12:09 A directory can be removed only if you are its owner, your current directory is hierarchically above the directory to be removed and the directory is empty.
12:23 Now type at the command prompt

"cd space testtree slash test3"

12:35 So, we are now in test3 directory which is a subdirectory under testtree.
12:42 Lets try to remove the testdir directory by typing the command "rmdir space testdir". Press enter.
12:55 We see it can't be done, because the current directory is not hierarchically above the directory to be removed.
13:02 So,we have to go to the directory which is hierarchically above testdir directory.
13:08 Type "cd space dot dot" and press enter.
13:14 Now, go back to our parent directory by typing the command "cd space dot dot".
13:20 Now, again try the previous command.
13:24 Type "rmdir space testdir". Press enter.
13:30 The testdir directory is successfully deleted. Note that, testdir directory was also empty.
13:38 Multiple directories or a hierarchy of directories can be removed at once.So, try to delete the testtree directory along with its subdirectory test3.
13:48 Type at the command prompt

"rmdir space testtree space testtree slash test3 "press enter.

14:02 See, it is giving the error message that 'testree' directory cannot be removed because testtree is not empty.
14:11 But one thing which you may miss is that testtree/test3 has been deleted as it was empty.
14:19 To check that, type at the command prompt "cd space testtree" and press enter.
14:27 Now type "ls" and press enter. See, the directory contains nothing. So, test3 was deleted.
14:36 So in this linux tutorial we have learnt about Linux Files and directories and how to work with Linux Directories. See them, move between them, make them,remove them.
14:49 This brings me to the end of this tutorial. Spoken Tutorials are a part of the Talk to a Teacher project, supported by the National Mission on Education through ICT.
15:03 More information this is available at the following link
15:08 This script has been contributed by ----------------------(name of the translator) and this is -----------------------(name of the recorder) from --------------------------(name of the place)signing off . Thanks for joining.

Contributors and Content Editors

PoojaMoolya, Sandhya.np14

Retrieved from "https://script.spoken-tutorial.org/index.php?title=BOSS-Linux/C2/File-System/English-timed&oldid=18358"