Linux-Ubuntu/C2/Linux-File-Ownership-and-Permissions/English

Title of the Script: Linux File Ownership and Permissions

Authors: Edupyramids

Keywords: Linux, File Ownership, File Permissions, chown, chmod, chgrp, Inodes, Hard link, Soft link, Symbolic link, Terminal commands, Linux file system, edupyramids, video tutorial.

Visual Cue	Narration
Slide 1 Title Slide	Welcome to this spoken tutorial on Linux File Ownership and Permissions.
Slide 2 Learning Objectives	In this tutorial, we will learn to: Manage file ownership and permissions using c h own and c h mod commands. Change file group ownership using chgrp command. Describe i nodes and view i node numbers of the files. Create and verify hard links and symbolic links in Linux.
Slide 3 System Requirements	To record this tutorial, I am using: Ubuntu O S version 24 point 04
Slide 4 Pre-requisites https://EduPyramids.org </u>	To follow this tutorial, learners should have Ubuntu version 24 point 04. For the prerequisite Linux tutorials please visit this website.
Slide 5 Code Files The following code file is required to practice this tutorial. file-attr.zip fa-commands.txt This file is provided in the Code Files link of this tutorial page.	The following code files are required to practice this tutorial. These files are provided in the Code Files link of this tutorial page.
Slide 6 File Attributes File-attributes.png	File attributes are properties linked to a file.Attributes define ownership and permissions. They include file type, size, and time details.They show who owns the file and who can access it. File attributes are viewed using the l s hyphen l command.
Switch to terminal Type cd Desktop/file-attr Press Enter Highlight the output /Desktop/file-attr$d	Let us move to the code files folder file hyphen attr provided along with the tutorial. I have downloaded it to my Desktop. Now switch to the terminal. Type c d space Desktop slash file hyphen a t t r and press Enter.Notice that the prompt path has changed.
Type ls -l example1 and press Enter Highlight the output point to the first character	Let us type l s space hyphen l space example1 and press Enter. Observe the output. The first character in the output shows the file type. If it is a hyphen, it denotes a regular file. If it is l, it denotes a symbolic link. If it is d, it denotes a directory. We see a hyphen here since example1 is a regular file.
highlight the next 9 characters	The next nine characters show permissions. First three denote owner permissions, Next three denote group permissions, Last three denote others permissions Here each set contains r, and w, means read, and write.
Highlight example1 highlight spoken	Here we can see that the owner of the file example1 is spoken.
Slide 7 chown command The chown command changes the ownership of a file or directory. This is an admin command. Only the root user can change the owner of a file or directory. chown [options] ownername filename or directoryname	* The c h own command changes the ownership of a file or directory. This is an admin command. Only the root user can change the ownership of a file or directory. Here is the syntax of the c h own command.
Slide 8 chown options -R: change permissions for all files in the current directory and its sub-directories. -c: report changes made to files. -f: prevent chown from displaying error messages.	The c h own command comes with various options like hyphen R, hyphen c, hyphen f and others.
	Now we will look at some examples.
Type sudo chown demo example1 press Enter.	Let us change the owner of the file example1. Type sudo space ch own space demo space example1 press Enter.
Type the sudo password if prompted.	Type the password if prompted again.
Type ls -l example1 press Enter Highlight the output	Let us see the file attributes of example1. Type l s space hyphen l space example1 and press Enter. Observe that the new owner of the file is demo. This works only if the user named demo exists. Otherwise we will get an invalid user error. Recall that we have given you an assignment in an earlier tutorial to create a user named demo. If the user does not exist, please create the user.
Type mkdir pond and press Enter. Type the command ls -l press Enter Highlight the pond directory details highlight examples 1 to 5.	Now, we will see how to change the owner of a directory. For that we will create a directory first. Type m k dir space pond and press Enter. To check, type l s space hyphen l and press Enter. It displays a directory named pond and all the existing files examples. Here we can see the owner of the directory pond is spoken
Type sudo chown -R demo pond	Let us change the owner of the directory pond to demo. Type the following command and press Enter Enter the sudo password, if required and press Enter again.
Press Ctrl+L keys together. Type ls -l and press Enter.	I will clear the screen by pressing Ctrl + L keys together for our convenience. Now type,l s space hyphen l and press Enter Here we can see the new owner of the directory pond is demo.
Slide 9 Changing File Permissions ch mod command is used to change the permissions of a file or directory. The name chmod stands for change mode. Using chmod we can grant or remove permissions for owner, group and others. read (r) write (w) execute (x) The command modifies only the permissions, not the file contents or ownership.	ch mod command is used to change the permissions of a file or directory. The name c h mod stands for change mode. Using chmod we can add or remove permissions such as: read, write, execute. These permissions can be changed for owner, group and others. It does not modify the file contents or change ownership.
Slide 10 Syntax of chmod command chmod [ugoa][+-=][rwx] file-or-directory	This is the syntax of the c h mod command.
Slide 11 Permissions using three-digit octal number chmod [0-7][0-7][0-7] file_or_directory Each digit represents: 1st digit → owner permissions 2nd digit → group permissions 3rd digit → others permissions Permission values: r = 4 (read) w = 2 (write) x = 1 (execute)	Alternatively, we can set permissions using a three digit octal number.
Press Clear and press Enter.	Now, we will look at some examples of ch mod. Let me clear the screen
Typechmod u+x example2 press Enter	To add execute permission to the owner of the file example2 type:ch mod space u plus x space example2 and press Enter. This will add the execute permission to the owner of the file example2.
type ls -l example2 press Enter highlight the permissions in the output	To check that, type l s space hyphen l space example2 and press Enter to see the changes It has assigned read, write, and execute permissions to the owner.Read and write only permissions to the group.And read-only permission to others, for the file example2.
Type chmod 751 example2 press Enter type ls -l example2 and press Enter Highlight the output	Now type the command ch mod space 751 space example2 press Enter This command gives the owner read, write, and execute permissions. To check type, ls space hyphen l space example2 and press Enter. Read and execute permissions to the group. And execute-only permission to others for the file example2.
type chmod a=r example2 and press Enter	To assign read-only permission to example2 for everyone, type the following command: ch mod space a equal to r space example2 and press Enter.
type ls -l example2 press Enter Highlight the output	Now type the command, l s space hyphen l space example2 and press Enter. Observe that the file example2 has read-only permission for all users.
Type chmod g+w example3 and press Enter	Let’s add the write permissions to the group for file example3. Type the commandch mod space g plus w space example3 and press Enter.
Typels -l example3 press Enter Highlight the output	Now type,l s space hyphen l space example3 press Enter. Note that the write permission has been added to the group.
Type chmod a-w example3 press Enter	To remove the write permissions for all,type the commandch mod space a hyphen w space example3 press Enter.
Type ls -l example3 press Enter Highlight the output	Now type, l s space hyphen l space example3 press Enter. Observe that write permission for all has been removed
Slide 12 chgrp command Ch-grp.png	ch grp command changes the group ownership of a file or directory. Group members can then access it based on the set permissions. Only the owner of a file or a privileged user can change the group.
Slide 13 Syntax of chgrp command The basic syntax of the ch grp command is:chgrp [options] group file To change the group of a directory and all its contents recursively:chgrp -R group directory Here, group is the new group name, and file or directory is the target.	The basic syntax of the ch g r p command is:ch grp options group file. To change the group of a directory and all its contents recursively type:ch grp hyphen R group directory. Here, group is the new group name, and file or directory is the target.
Switch to terminal Press Clear and press Enter. type ls -l example4 press Enter Highlight the permissions in the output	Let's look at some examples of ch grp commands. Type the command, l s space hyphen l space example4 and press Enter. Here we can see the group permission is given for the user spoken.
Type sudo chgrp demo example4 press Enter	To change the group permission, type the commandsudo space ch grp space demo space example4 press Enter.Enter the sudo password, if required.
Type ls -l example4 press Enter Highlight the permissions in the output	Now type the commandl s space hyphen l space example4 press Enter Observe that the group has changed from spoken to demo
Slide 14 Inode	An i node is a unique number that stores file or directory information. Files are hard links to i nodes, which the system uses to access data.
Switch to the terminal type the command ls -i example5 press Enter Highlight the number in the output	We can use l s space hyphen i command to see the i node number of a file. type the command, l s space hyphen i space example5 press Enter. The number written before the file is the i node number of the file. The i node number may vary for the users.
Slide 15 Hard Links	A hard link is another name for an existing file. Both files point to the same i node. Since they share the same i node, they share the same data on disk. The file is not copied, only a new filename is created.
Slide 16 Inode and Hard Links	An i node can have multiple directory entries through hard links. Hard links let multiple filenames point to the same i node. To create links in Linux, we use the ln command.
Slide 17 Syntax of ln ln source link	The syntax of ln command to create a hard link is: ln space source space link The source is an existing file, and the link is the new filename. Both files point to the same i node and share the same data. Any change made to one file will reflect in the other file.
Type: clear and press enter ln example2 exampleln press Enter Point to the command.	Now we will look at some examples of hard links Let me clear the screen again. Type the command, l n space example2 space example l n press Enter. This command creates a hard link named exampleln to the file example2.
Type ls -i example2 exampleln press Enter Highlight to the output	To display the i node number of both the files, type the commandl s space hyphen i space example2 space exampleln and press Enter. The output shows that both files have the same i node number. File exampleln is the hard link for file example2
Slide 18 Soft Link	A soft link or a symbolic link is a special type of file. It holds a reference to another file or directory. This reference is an absolute or relative path.
ln -s target-filename symbolic-filename	The syntax of l n command to create soft links isl n space hyphen s space target hyphen filename space symbolic hyphen filename.
	Now we will look at some examples of soft links.
type ln -s example2 examplesoft press Enter	To create a soft link, type the command l n space hyphen s space example2 space examplesoft and press Enter.
type the command ls -li example2 examplesoft press Enter	Now, let us display the i node number and list both the files. Type the command, l s space hyphen l i space example2 space examplesoft press Enter. Observe that the i node number of both the files is different. examplesoft is a soft link of example2.
Slide 19 Summary In this tutorial, we have learnt to: Manage file ownership and permissions using chown and chmod commands. Change file group ownership using chgrp command. Describe inodes and view inode numbers of the files. Create and verify hard links and symbolic links in Linux.	With this we come to the end of this tutorial. Let us summarise.
Slide 20 Assignment Create a file named sample.txt. Display its permissions using the ls -l command. Change the permissions so that only the owner can read and write the file. Display the inode number of sample.txt.	As an Assignment, please do the following.
Slide 21 Thank you	This Spoken Tutorial is brought to you by EduPyramids Educational Services Private Limited SINE IIT Bombay.Thank you.

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