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

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{| border=1
 
{| border=1
−
!Time
+
|'''Time'''
−
!Narration
+
|'''Narration'''
 
|-
 
|-
−
| 0:00
+
| 00:00
−
|Welcome to this spoken tutorial on Linux File System.
+
|Welcome to this spoken tutorial on '''Linux File System'''.
 
|-
 
|-
−
| 0:04
+
| 00:04
−
|I am using Ubuntu 10.04.  
+
|I am using '''Ubuntu 10.04'''.  
 
|-
 
|-
−
| 0:07
+
| 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'''.  
 
|-
 
|-
−
| 0:13
+
| 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
 
|-
 
|-
−
| 0:25
+
| 00:25
−
|Also note that linux is case sensitive.
+
|Also note that Linux is ''case sensitive''.
 
|-
 
|-
−
| 0:28
+
| 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.  
 
|-
 
|-
−
| 0:36
+
| 00:36
 
|In Linux almost everything is a file.  
 
|In Linux almost everything is a file.  
 
|-
 
|-
−
| 0:39
+
| 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.  
 
|-
 
|-
−
| 0:47
+
| 00:47
−
|Similarly in Linux a file is a container for storing information.  
+
|Similarly, in Linux a file is a container for storing information.  
 
|-
 
|-
−
| 0:53
+
| 00:53
−
|Next what is a directory?  
+
|Next, what is a directory?  
 
|-
 
|-
−
| 0:56
+
| 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.
 
|-
 
|-
−
| 1:02
+
| 01:02
−
|A directory helps us in organising our files in a systematic manner.  
+
|A directory helps us in organizing our files in a systematic manner.  
 
|-
 
|-
−
| 1:08
+
| 01:08
−
|This is like what we call folders in Windows.
+
|This is like what we call ''folders'' in Windows.
 
|-
 
|-
−
| 1:12
+
| 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.  
 
|-
 
|-
−
| 1:20
+
| 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.
 
|-
 
|-
−
| 1:31
+
| 01:31
 
|Though 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.  
 
|-
 
|-
−
| 1:42
+
| 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''.  
 
|-
 
|-
−
| 1:55
+
| 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.  
+
|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.  
 
|-
 
|-
−
| 2:08
+
| 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.
+
|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.
 
|-
 
|-
−
|2:23
+
|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 doesn't actually store other files ,it is itself a file that holds the 'inode' numbers and names of other files.  
 
|-
 
|-
−
| 2:37
+
| 02:37
−
|In fact in Linux there are three kinds of files:
+
|In fact, in Linux there are three kinds of files:
 
|-
 
|-
−
| 2:41
+
| 02:41
−
|1 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.
 
|-
 
|-
−
| 2:48
+
| 02:48
 
|2 Directories: As we just saw in the previous slides.
 
|2 Directories: As we just saw in the previous slides.
 
|-
 
|-
−
| 2:52
+
| 02:52
 
|3 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.  
 
|-
 
|-
−
| 2:59
+
| 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 Hard disk 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.
 
|-
 
|-
−
| 3:15
+
| 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.  
 
|-
 
|-
−
| 3:22
+
| 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 sub-directories will have a parent – child relationship with each other. This gives rise to the '''Linux File System Tree'''.
 
|-
 
|-
−
| 3:34
+
| 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 front-slash /). It contains all the other files and directories.  
 
|-
 
|-
−
| 3:42
+
| 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.  
 
|-
 
|-
−
| 3:51
+
| 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.  
 
|-
 
|-
−
| 3:56
+
| 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.
 
|-
 
|-
−
| 4:01
+
| 04:01
 
|Sounds interesting!! Indeed it is. As we will see.
 
|Sounds interesting!! Indeed it is. As we will see.
 
|-
 
|-
−
| 4:05
+
| 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''.  
 
|-
 
|-
−
| 4:11
+
| 04:11
−
|Now Switch to the terminal.
+
|Now, switch to the terminal.
 
|-
 
|-
−
| 4:13
+
| 04:13
−
| Ctrl+alt+T helps to start a terminal in Ubuntu.  
+
| '''Ctrl+alt+T''' helps to start a terminal in Ubuntu.  
 
|-
 
|-
−
| 4:17
+
| 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.  
+
|This command may not work in all Unix systems, however. A general procedure to open a terminal is already explained in another spoken tutorial.  
 
|-
 
|-
−
| 4:27
+
| 04:27
−
|To see the home directory , Type at the command prompt
+
|To see the home directory , Type at the command prompt:
−
"echo space dollar H-O-M-E in capital" and press enter.
+
"echo space dollar H-O-M-E in capital" and press Enter.
 
|-
 
|-
−
| 4:40
+
| 04:40
−
|This gives the pathname of our home directory.  
+
|This gives the '''pathname''' of our home directory.  
 
|-
 
|-
−
| 4:44
+
| 04:44
 
|We can move around from one directory to other.  
 
|We can move around from one directory to other.  
 
|-
 
|-
−
| 4:47
+
| 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.
+
|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.
 
|-
 
|-
−
| 4:56
+
| 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'''.
 
|-
 
|-
−
| 5:03
+
| 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.  
 
|-
 
|-
−
| 5:13
+
| 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.  
 
|-
 
|-
−
| 5:17
+
| 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.
 
|-
 
|-
−
| 5:22
+
| 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.
 
|-
 
|-
−
| 5:28
+
| 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.
 
|-
 
|-
−
|5:37
+
|05:37
 
| So, now we are placed in this directory.
 
| So, now we are placed in this directory.
 
|-
 
|-
−
| 5:41
+
| 05:41
−
|Now say we want to move to slash usr directory. So, type  
+
|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.
+
"cd space slash usr" . Remember here slash in Linux means ''front slash'' and press Enter.
 
|-
 
|-
−
| 5:56
+
| 05:56
−
|Now lets see our current directory. Type pwd and press enter.
+
|Now let's see our current directory. Type '''pwd''' and press Enter.
 
|-
 
|-
−
| 6:03
+
| 06:03
−
|Yes we have moved to slash usr directory.  
+
|Yes! We have moved to ''slash usr'' (/usr) directory.  
 
|-
 
|-
−
| 6:08
+
| 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'''.
 
|-
 
|-
−
| 6:18
+
| 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.  
 
|-
 
|-
−
| 6:23
+
| 06:23
 
|Here we need to know two special characters.
 
|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.  
+
'''dot''' that represent the current directory and '''dot dot''' that represent the '''parent directory''' of the current directory.  
 
|-
 
|-
−
| 6:36
+
| 06:36
−
|Now let us have a brief session on cd command
+
|Now, let us have a brief session on '''cd''' command.
 
|-
 
|-
−
| 6:40
+
| 06:40
−
|The command cd without any argument is used to move back to the home directory.  
+
|The command '''cd''' without any argument is used to move back to the '''home''' directory.  
 
|-
 
|-
−
| 6:46
+
| 06:46
−
|Type at the command prompt "cd" and press enter.  
+
|Type at the command prompt: "cd" and press Enter.  
 
|-
 
|-
−
| 6:51
+
| 06:51
−
|Now check our current directory by the pwd command.  
+
|Now check our current directory by the '''pwd''' command.  
 
|-
 
|-
−
| 6:55
+
| 06:55
 
|So, now we are back in our home directory
 
|So, now we are back in our home directory
 
<nowiki>/home/gnuhata [ narration- slash home slash gnuhata ] </nowiki>
 
<nowiki>/home/gnuhata [ narration- slash home slash gnuhata ] </nowiki>
 
|-
 
|-
−
| 7:01
+
| 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.
 
|-
 
|-
−
| 7:13
+
| 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  
 
|-
 
|-
−
| 7:26
+
| 07:26
−
|Let us go to the parent directory from 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'.  
 
|-
 
|-
−
| 7:33
+
| 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.  
 
|-
 
|-
−
| 7:40
+
| 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'''.
 
|-
 
|-
−
| 7:51
+
| 07:51
−
|Now lets try to move to a subdirectory of the current directory using dot.  
+
|Now let's try to move to a subdirectory of the current directory using '''dot'''.  
 
|-
 
|-
−
| 7:58
+
| 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.
 
|-
 
|-
−
| 8:09
+
| 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'''.
 
|-
 
|-
−
| 8:19
+
| 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.
 
|-
 
|-
−
| 8:23
+
| 08:23
−
|To go back to our home directory by cd command.
+
|To go back to our home directory by 'cd' command,
−
Type cd and press enter.
+
type cd and press Enter.
 
|-
 
|-
−
| 8:32
+
| 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''' .  
 
|-
 
|-
−
| 8:41
+
| 08:41
 
|<nowiki>We can combine any number of .. [narration - dot dot] separated by / [narration- slash] in a relative path . </nowiki>
 
|<nowiki>We can combine any number of .. [narration - dot dot] separated by / [narration- slash] in a relative path . </nowiki>
 
|-
 
|-
−
| 8:47
+
| 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.
+
|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.
 
|-
 
|-
−
| 9:05
+
| 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?  
 
|-
 
|-
−
| 9:12
+
| 09:12
−
|Type at the command prompt
+
|Type at the command prompt:
−
"cd space dot dot slash dot dot slash bin" and press enter.  
+
"cd space dot dot slash dot dot slash bin" and press Enter.  
 
|-
 
|-
−
| 9:23
+
| 09:23
−
|Check our current directory by the command pwd.  
+
|Check our current directory by the command '''pwd'''.  
 
<nowiki>We are at /bin [narration - slash bin] </nowiki>
 
<nowiki>We are at /bin [narration - slash bin] </nowiki>
 
|-
 
|-
−
| 9:30
+
| 09:30
−
|<nowiki>The first .. [narration-dot dot] takes us from /home/gnuhata [narration - slash home slash gnuhata] to /home [narration - slash home] .  
+
|<nowiki>The first .. [narration-dot dot] takes us from /home/gnuhata [narration - slash home slash gnuhata] to /home [narration - slash home].</nowiki>
 +
 
 
|-
 
|-
−
| 9:37
+
| 09:37
−
|The next takes us from /home to </nowiki>root.  
+
|<nowiki>The next takes us from /home to </nowiki>root.  
 
|-
 
|-
−
| 9:43
+
| 09:43
−
|Now from / or root, we have moved to /bin directory.
+
|Now from '/' or 'root', we have moved to '/bin' directory.
 
|-
 
|-
−
| 9:48
+
| 09:48
−
|Go back to our home directory by the command cd.  
+
|Go back to our home directory by the command 'cd'.  
 
|-
 
|-
−
| 9:52
+
| 09:52
−
|To create a directory we use the mkdir command.  
+
|To create a directory, we use the '''mkdir''' command.  
  
 
|-
 
|-
−
| 9:56
+
| 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.
 
|-
 
|-
 
| 10:04
 
| 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.
 
|-
 
|-
 
| 10:15
 
| 10:15
−
|This creates the testdir directory successfully.  
+
|This creates the 'testdir' directory successfully.  
 
|-
 
|-
 
| 10:19
 
| 10:19
Line 264: Line 265:
 
|-
 
|-
 
| 10:30
 
| 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.
 
|-
 
|-
 
| 10:43
 
| 10:43
Line 270: Line 271:
 
|-
 
|-
 
| 10:49
 
| 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.
 
|-
 
|-
 
| 11:06
 
| 11:06
Line 276: Line 277:
 
|-
 
|-
 
| 11:20
 
| 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'.  
 
|-
 
|-
 
| 11:28
 
| 11:28
Line 282: Line 283:
 
|-
 
|-
 
| 11:47
 
| 11:47
−
|Similar to 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.
 
|-
 
|-
 
| 11:56
 
| 11:56
Line 291: Line 292:
 
|-
 
|-
 
| 12:23
 
| 12:23
−
|Now type at the command prompt
+
|Now type at the command prompt:
 
"cd space testtree slash test3"
 
"cd space testtree slash test3"
 
|-
 
|-
Line 298: Line 299:
 
|-
 
|-
 
| 12:42
 
| 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.  
 
|-
 
|-
 
| 12:55
 
| 12:55
Line 307: Line 308:
 
|-
 
|-
 
| 13:08
 
| 13:08
−
|Type "cd space dot dot" and press enter.  
+
|Type: "cd space dot dot" and press Enter.  
 
|-
 
|-
 
| 13:14
 
| 13:14
Line 316: Line 317:
 
|-
 
|-
 
| 13:24
 
| 13:24
−
|Type "rmdir space testdir". Press enter.  
+
|Type "rmdir space testdir". Press Enter.  
 
|-
 
|-
 
| 13:30
 
| 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.
 
|-
 
|-
 
| 13:38
 
| 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'.  
 
|-
 
|-
 
| 13:48
 
| 13:48
−
|Type at the command prompt
+
|Type at the command prompt:
−
"rmdir space testtree space testtree slash test3 "press enter.
+
"rmdir space testtree space testtree slash test3" press Enter.
 
|-
 
|-
 
| 14:02
 
| 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.  
 
|-
 
|-
 
| 14:11
 
| 14:11
Line 335: Line 336:
 
|-
 
|-
 
| 14:19
 
| 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.
 
|-
 
|-
 
| 14:27
 
| 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.
 
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|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.  
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|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.  
 
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|More information on this is available at the following link.
 
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| 15:08

Latest revision as of 07:22, 9 March 2015

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 organizing 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 doesn't 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 Hard disk 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 sub-directories 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 front-slash /). 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 let's see our current directory. Type pwd and press Enter.
06:03 Yes! We have moved to slash usr (/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 let's 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 on 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

Minal, Pratik kamble, Sandhya.np14, Vasudeva ahitanal

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