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

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 the chown command is: chown space options space ownername space filename or directoryname.
01:13	We may give the 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.
01:32	-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 testchown is "shahid".
02:18	To change the owner of the file, type the command sudo space c-h own space a-n-u-s-h-a anusha space testchown that is t-e-s-t-c-h-o-w-n and 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 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 We may give the following options with the 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 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, 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:
07:44	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 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 a 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 i.e. 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 is contributed by Anusha Ambala and Shahid. Thanks or joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Pravin1389, Sandhya.np14