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

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|Hard links are to associate multiple directory entries with a single inode.  
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|Hard-links are to associate multiple directory entries with a single inode.  
 
'''ln''' is the command to make link.  
 
'''ln''' is the command to make link.  
 
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| The syntax of '''ln''' command to create the hard link is:  
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| The syntax of '''ln''' command to create the hard-link is:  
 
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| Now we will look at some examples of hard links.  
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|Here we can see that inode number of both the files are same, file 'exampleln' is the hard link for file 'example1'.  
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|Here we can see that 'inode number' of both the files are same, file 'exampleln' is the '''hard link''' for file 'example1'.  
 
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| Soft link symbolic link is a special type of file that contains a reference to another file or directory in the form of an '''absolute''' or '''relative path'''.  
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| '''Soft link''' '''symbolic link''' is a special type of file that contains a reference to another file or directory in the form of an '''absolute''' or '''relative path'''.  
 
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| The syntax of '''ln''' command to create soft links is:  
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| Now we will look at some examples of soft link.  
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| To create the soft link, type the command:  
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$ ln space -s space example1 space examplesoft  
 
$ ln space -s space example1 space examplesoft  
 
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|Here we can see that inode-number of both the files are different and 'examplesoft' is a softlink of example1.  
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Revision as of 21:28, 10 March 2015

Time Narration
00:00 Welcome to this spoken tutorial on Linux File Attributes.
00:05 The prerequisites for this tutorial is to create empty files named as example1, example2, example3, example4, example5, and testchown.
00:18 Please create empty directories named as test_chown and directory1 also.
00:25 A file attribute is metadata that describes or is associated with a computer file.
00:33 File attribute is the characteristics that describes a file such as owner, file type, access permissions etc.
00:45 'c-h own' command is used to change the ownership of the file or directory. This is an admin command, root user only can change the owner of a file or directory.
01:00 The syntax of chown command is chown space options space ownername space filename or directoryname
01:13 We may give following options with chown command.
01:18 -R : To change the permission on files that are in the sub-directories of the directory that you are currently in.
01:28 -c : Change the permission for each file.
01:33 -f : Prevents chown from displaying error messages.
01:37 Now we will look at some examples.
01:40 So, go to the terminal. We will move to the directory where we have created empty files and folders. For that, cd space Desktop slash file attribute and press Enter.
01:56 Now type the command:

$ ls space -l space testchown that is t-e-s-t-c-h-o-w-n and press Enter.

02:11 Here we can see the owner of the file 'testchown' is shahid.
02:18 To change the owner of the file, type the command:

$ sudo space c-h own space that is a-n-u-s-h-a anusha space testchown that is t-e-s-t-c-h-o-w-n press Enter.

02:36 Enter the sudo password and press Enter again. Press Enter.
02:44 Now, type: $ ls space -l space t-e-s-t-c-h-o-w-n

and press Enter. Here we can see the new owner of the file is anusha.

03:03 Now we will see how to change owner of the directory.
03:07 Type the command: $ ls -l and press Enter.

Here we can see the owner of the directory 'test_chown' is shahid.

03:21 To change the owner of the directory, type the command:
03:26 $ sudo space chown space minus capital R space a-n-u-s-h-a anusha space test_chown which is directory name and press Enter.
03:44 Enter the sudo password if required and press Enter again.
03:49 I will clear the screen by pressing Ctrl+L for our convenience. Now type: $ ls space -l and press Enter.

Here we can see the new owner of the directory is anusha.

04:06 chmod command is used to change the access mode or permissions of one or more files.
04:13 Syntax of the chmod command is

chmod space [options] space mode space filename space chmod space [options] space filename

We may give the following options with chmod command.

04:29 -c : Print information about files that are changed.
04:34 -f : Do not notify user of files that chmod cannot change.
04:41 There are following types of access or permissions:
04:44 r : Read

w : Write

x : Execute

s : Set user (or group) ID

04:54 Alternatively, we may specify permissions by a three-digit octal number.
05:00 The first digit stands for owner permission, the second stands for group permission, and the third stands for others permission.
05:09 Permissions are calculated by adding the following octal values:

4 that is Read

2 that is Write

1 that is Execute

05:20 Now we will look at some examples of chmod. Move to terminal and enter the command to add execute-by-user permission to file 'example1'.
05:30 Before that, I will again clear the screen by pressing Ctrl+l.
05:36 Now, let's type:

$ chmod space u+x space example1 press Enter.

05:49 Now type: $ ls space -l space example1

press Enter to see the changes.

06:01 Here you can see, to assign the read/write/execute permission by owner, read/execute permission by group, and execute-only permission by others to file example1.
06:15 Now type the command: $ chmod space 751 space example1

press Enter.

06:26 Now type:

$ ls space -l space example1 and press Enter.

06:35 Here we can see that above command has assigned the read/write/execute permission by owner, read/execute permission by group, and execute-only permission by others to file example1.
06:52 To assign read-only permission to file example1 for everyone, type the command: $ chmod space =r space example1

and press Enter.

07:08 Now type the command: $ ls space -l space example1

press Enter.

07:19 Here we can see that the 'read only' permission has been assigned to file example1 for everyone.
07:30 To change the permission recursively and assign the read and execute access for everyone and also write access for the owner of the directory 'directory1', type the command:
7:44 $ chmod space minus capital R space 755 space directory1

press Enter.

08:00 Now type:

$ ls space -l press Enter to see the changes.

08:09 To give the user execute permission on file example2, type the command:

$ chmod space u+x space example2 press Enter.

08:27 Now type the command:

$ ls space -l space example2 and press Enter.

08:40 Here we can see that execute permission has been assigned to user on 'example2'.
08:50 To add the write permissions to the group for file example3

type the command: $ chmod space g+w space example3 press Enter.

09:10 and now type:

$ ls space -l space example3 press Enter.

09:23 Here we can see the write permission has been added to group.
09:30 To remove the write permissions for all, type the command:

$ chmod space a-w space example3 press Enter.

09:45 Now, type:

$ ls space -l space example3 press Enter.

09:55 Here we can see the write permission, for all, has been removed.
10:02 chgrp command is used to change the group of one or more files to new group.
10:10 New group is either a group ID number or a group name located in /etc/group.
10:20 Only the owner of a file or a privileged user may change the group.
10:26 The syntax for the chgrp command is

chgrp space [options] space newgroup space files.

10:36 Let's go to terminal. Now we will look at some examples of chgrp command.

Type the command: $ ls space -l space example4 press Enter.

10:57 Here we can see the group permission is for user shahid.
11:03 To change the group permission, type the command: $ sudo space chgrp space rohit space example4
11:20 press Enter.

Enter the sudo password if required.

11:27 Now type the command: $ ls space -l space example4

press Enter.

11:38 Here, we can see that the group has changed from shahid to rohit.
11:46 The 'inode number' is a unique integer assigned to the device.
11:51 'Inode' stores basic information about a regular file or a directory.
11:57 All the files are hard-links to inodes.
12:00 Whenever a program refers to a file by name, the system actually uses the filename to search for the corresponding 'inode'.
12:12 We can use 'ls space -i' command to see the 'inode number' of a file.
12:19 Type the command: $ ls space -i space example5

press Enter.

12:29 Number written before the file is the 'inode number' of the file.
12:35 'Inodes' are associated with precisely one directory at a time.
12:41 Hard-links are to associate multiple directory entries with a single inode.

ln is the command to make link.

12:52 The syntax of ln command to create the hard-link is:
12:57 ln space source space link where 'source' is an existing file and 'link' is the file to create.
13:06 Now we will look at some examples of hard-links.
13:10 Let me clear the screen again. Now type the command:

$ ln space example1 space exampleln press Enter.

13:25 To display the 'inode number' of both the files, type the command:

$ ls space -i space example1 space exampleln press Enter.

13:41 Here we can see that 'inode number' of both the files are same, file 'exampleln' is the hard link for file 'example1'.
13:54 Soft link symbolic link is a special type of file that contains a reference to another file or directory in the form of an absolute or relative path.
14:07 The syntax of ln command to create soft-links is:
14:12 ln space -s space {target-filename} space {symbolic-filename}
14:19 Now we will look at some examples of soft-link.
14:25 To create the soft-link, type the command:

$ ln space -s space example1 space examplesoft

14:40 press Enter.
14:43 Now, to display the inode-number and list of both the files, type the command:

$ ls space -li space example1 space examplesoft

15:01 press Enter.
15:03 Here we can see that inode-number of both the files are different and 'examplesoft' is a soft-link of example1.
15:16 So, in this tutorial, we have learnt about the Linux Files Attributes like changing permission, ownership and group of a file.
15:26 We also learnt about the inode, soft and hard links of a file.
15:31 This brings me to the end of this tutorial.
15:35 Spoken Tutorials are a part of the Talk to a Teacher project, supported by the National Mission on Education through ICT.
15:44 More information on the same is available at the following link.
15:50 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, PoojaMoolya, Pratik kamble, Ravikala, Sandhya.np14

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