BOSS-Linux/C2/File-Attributes/English-timed

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Time Narration
00:01 Welcome to this spoken tutorial on Linux File Attributes.
00:05 The prerequisite 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.
00:34 File attribute is the characteristics that describe a file, such as owner, file type, access permissions, etc.
00:46 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.
01:01 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 subdirectories of the directory that you are currently in.
01:28 -c : Change the permission for each file.
01:32 -f : Prevents ch own from displaying error messages.
01:37 Now we will look at some examples
01:41 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 space -l and press Enter

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

03:22 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 Clt+L for our convenience. Now type ls space -l 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 that is Read

w that is Write

x that is Execute

s that is 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 other's 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 Clt+l.
05:36 Now lets 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
09:24 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 newgroup.
10:10 Newgroup 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 Lets 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 softlink 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 is contributed by Anusha Ambala and Shahid. Thanks or joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Pravin1389, Sandhya.np14