Sandhya.np14 at 16:18, 10 August 2015

2015-08-10T16:18:22Z

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PoojaMoolya at 07:20, 4 December 2014

2014-12-04T07:20:52Z

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PoojaMoolya at 07:20, 4 December 2014

2014-12-04T07:20:26Z

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PoojaMoolya: 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..."

2014-11-25T11:45:44Z

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..."

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{| 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 that you know how to get started with the Linux operating system and have some basic idea about commands.
|-
| 00:16
|If you are interested, it is available through another spoken tutorial, on the following website http://spoken-tutorial.org
|-
| 00:28
|Also note that linux is case sensitive.
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| 00:32
| All the commands used in this tutorial are in lower case unless otherwise mentioned.
|-
| 00:41
|In Linux almost everything is a file.
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| 00:44
|So what is a file? In real life we know that a file is where we store our documents and papers.
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| 00:54
|Similarly in Linux a file is a container for storing information.
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| 01:00
|Next what is a directory?
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| 01:03
|A directory can be understood as a collection of files and other (sub)directories.
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| 01:10
|A directory helps us in organising our files in a systematic manner.
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| 01:16
|This is like what we call folders in Windows.
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| 01:20
| It allows different users to have their own directories with their files which others cannot access or modify.
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| 01:30
|Also if there are no directories, all the files on the system need to have unique names,which would be very difficult to maintain.
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| 01:41
|These definitions of files and directories are good to get a general feel about them, they are not entirely accurate.
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| 01:51
|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.
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| 02:05
|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.
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| 02:20
|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.
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|02:35
|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.
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| 02:49
|In fact in Linux there are three kinds of files:
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| 02:54
|Regular Files or Ordinary files: It contains only data , as a stream of characters.
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| 03:01
|Directories: As we just saw in the previous slides.
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| 03:07
|Device Files: All hardware devices and peripherals are represented as files in Linux.
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| 03:14
|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.
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| 03:32
|All files in Linux are related, in short all form a family much like we do.
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| 03:39
|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.
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| 03:52
|At the top is the root( denoted by a frontslash /). It contains all the other files and directories.
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| 04:04
|This also helps in easy navigation from one file or directory to other, if we know the correct path.
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| 04:12
|As we work with a Linux file system, it seems that we are moving along this tree.
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| 04:18
|One command and there you are teleported from one place to other.
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| 04:24
|Sounds interesting!! Indeed it is. As we will see.
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| 04:29
|When we login into the Linux system we are by default in a home directory.
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| 04:36
|Now Switch to the terminal.

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| 04:39
|To see the home directory , Type at the command prompt "'echo space dollar H-O-M-E in capital"' and press enter.
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| 04:53
|This gives the pathname of our '''home''' directory.
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| 04:57
|We can move around from one directory to other.
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| 05:01
|But any time we can be in one directory and this directory is known as the current directory or working directory.
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| 05:09
|The '''pwd''' command helps us to see the current directory. '''pwd''' stands for present working directory.
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| 05:18
|Type at the command prompt '"pwd'" and press enter. Now this is our present working directory.
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| 05:28
|We have said that we can move from one directory to other.
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| 05:32
|But how do we do so? We have the '''cd''' command for this purpose.
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| 05:39
|You have to type the command '''cd''' followed by the pathname of the directory you want to move to.
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| 05:47
|Lets again see our current directory by typing '''pwd''' at the command prompt and press enter.
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|05:57
| So, now we are placed in this directory.
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| 06:01
|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.
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| 06:17
|Now lets see our current directory. Type '''pwd''' and press enter.
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| 06:24
|Yes we have moved to '''slash usr''' directory.
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| 06:30
|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.
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| 06:42
|Instead we may use Relative pathnames that begin from the current directory.
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| 06:48
|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.
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| 07:02
|Now let us have a brief session on '''cd''' command
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| 07:06
|The command '''cd''' without any argument is used to move back that to the home directory.
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| 07:13
|Type at the command prompt "'cd'" and press enter.
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| 07:19
|Now check our current directory by the '''pwd''' command.
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| 07:23
|So, now we are back in our home directory '''/home/gnuhata''' [ slash home slash gnuhata ]

|-
| 07:30
|Now let us move to music directory. Type at the command prompt "'cd space Music(M in capital) slash"' and press enter
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| 07:43
|Now check our current directory by the '''pwd''' command. '''pwd''' and press enter. See, we have moved ''' /home/gnuhata/Music '''
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| 07:57
|Let us go to the parent directory of Music. For that you have to use cd command with dot dot.
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| 08:04
|Type at the command prompt '''cd space dot dot''' and press enter.
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| 08:11
|Now check our present directory by typing '''pwd.''' We are again in '''/home/gnuhata'''
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| 08:23
|Now lets try to move to a subdirectory of the current directory using dot.
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| 08:30
|Type at the command prompt '''cd space dot slash Documents(D in capital) slash'''. Press enter.
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| 08:42
|Check our current directory by typing '''pwd.''' We are at ''' /home/gnuhata/Documents'''
|-
| 08:53
|Let me clear the screen by pressing control L. So you can see clearly.
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| 08:58
|To go back to our home directory by '''cd''' command. Type '''cd''' and press enter.
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| 09:07
|Again check our current directory by '''pwd''' command. We are back to '''/home/gnuhata''' .
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| 09:17
|We can combine any number of dot dot separated by slash in a relative path .
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| 09:23
|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.'''
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| 09:43
| So, now we are in '''/home/gnuhata.''' Now how can we go to the bin directory?
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| 09:51
|Type at the command prompt "'cd space dot dot slash dot dot slash bin'" and press enter.

|-
| 10:03
|Check our current directory by the command '''pwd.''' We are at /bin (slash bin)

|-
| 10:11
|The first .. (dot dot) takes us from /home/gnuhata (slash home slash gnuhata) to /home (slash home)

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| 10:18
|The next takes us from '''slash home''' to root.
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| 10:24
|Now from root or slash, we have moved to /bin directory.
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| 10:30
|Go back to our home directory by the command '''cd.'''
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| 10:34
|To create a directory we use the '''mkdir''' command.

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| 10:40
|You have to type the command and name of directory to be created and a directory would be created under the current directory.
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| 10:49
|To create a directory named '''testdir''', type the command '"mkdir space testdir'" and press enter.
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| 11:01
|This creates the '''testdir''' directory successfully.
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| 11:05
|Note that, there is no explicit notification of successful directory creation or removal.
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| 11:13
| If you do not get any error message, it denotes successful execution.
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| 11:18
|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.
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| 11:33
|This process can be used for making multiple directories or even a hierarchy of directories.
|-
| 11:39
|Type "'mkdir space test1 space test2''' and press enter ,this will make two directories named '''test1''' and '''test2''' under the present directory.
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| 11:57
|Type "'mkdir space testtree space testtree slash test3'".
|-
| 12:11
|This will make a directory '''testtree''' and another directory '''test3''' which is a sub-directory under '''testtree.'''
|-
| 12:20
|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
|Similar to the '''mkdir''' is the '''rmdir''' command which is used for removing a directory or directories.
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| 12:50
|The command "'rmdir space test1'" removes the '''test1''' directory successfully.
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| 13:00
|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.
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| 13:13
|Now type at the command prompt '"cd space testtree slash test3"'
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| 13:25
|So, we are now in '''test3''' directory which is a subdirectory under '''testtree.'''
|-
| 13:33
|Lets try to remove the '''testdir''' directory by typing the command '"rmdir space testdir'". Press enter.
|-
| 13:46
|We see it can't be done, because the current directory is not hierarchically above the directory to be removed.
|-
| 13:54
|So,we have to go to the directory which is hierarchically above '''testdir''' directory.
|-
| 14:00
|Type "'cd space dot dot"' and press enter.
|-
| 14:06
|Now, go back to our parent directory by typing the command "'cd space dot dot'".
|-
| 14:13
|Now, again try the previous command.
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| 14:16
|Type "rmdir space testdir". Press enter.
|-
| 14:23
|The '''testdir''' directory is successfully deleted. Note that, '''testdir''' directory was also empty.
|-
| 14:32
|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
|Type at the command prompt '"rmdir space testtree space testtree slash test3'" press enter.
|-
| 14:57
|See, it is giving the error message that '''testree''' directory cannot be removed because testtree is not empty.
|-
| 15:07
|But one thing which you may miss is that '''testtree slash test3''' has been deleted as it was empty.
|-
| 15:16
|To check that, type at the command prompt "'cd space testtree"' and press enter.
|-
| 15:25
|Now type "'ls'" and press enter. See, the directory contains nothing. So, '''test3''' was deleted.
|-
| 15:34
|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
|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
|More information this is available at the following link
|-
| 16:08
|This is Anusha Kadambala signing off. Thanks for joining.

|}

BOSS-Linux/C2/File-System/English-timed - Revision history

Sandhya.np14 at 16:18, 10 August 2015

PoojaMoolya at 07:20, 4 December 2014

PoojaMoolya at 07:20, 4 December 2014

PoojaMoolya: 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..."