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[No audio]

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File Ownership. In this lesson, we will cover how

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files and directories are owned, and how we could

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change the ownership of those files and

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directories. So the file ownerships are created on

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user level and a group level. There are two owners

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of a file or directory, a user, the one who

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creates the file or directory, and the second one

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is a group, the user the group that belongs to. If

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you are, if you belong to two different group, and

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permission applies that second group has read

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permissions, or you could delete a file or

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directory, as long as you are in that group, then

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you will have the right. Command to change file

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ownership is change owned, which is also known as

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chown and change group, chgrp. chown

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changes the ownership of a file, chgrp

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changes the group ownership of a file. Recursive

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ownership change option. If you are using an

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option with chown or chgrp with -R,

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it will not only change that

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directory, but also all the files and directories

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within that parent directory. If you look at the

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example of Windows, let's say we have this folder

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called Videos, and when I click, when I do right

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click and go to Properties, we'll see that under

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Security, this file is owned by the SYSTEM, and

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iafzal, and Administrators. So you see these two

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people here, these are the group and the single

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user, one person here is just the user. And again,

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the SYSTEM is a group. So group, system, and

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administrator own this file or folder called

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Videos. And the user who created that folder is iafzal.

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And you see at the bottom, it tells you

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whether that user has read, write, executable

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permission, you can see right here, it has all the

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permissions that we talked about. In our Linux

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machine when we log into our Linux machine,

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again, the first thing we do is see who we are. So

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we are iafzal. See what files or directories we

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have. These are all the listing of files and

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directories we have. Now here, and the first

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second, and here the third column. The third

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column tells you who owns this file. Let's say we

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go to lisa, we created this file lisa, and the

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person who owns this file lisa is the user iafzal,

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or yourself, yourself in this case. The fourth

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column right here is the group name in this case

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is iafzal again, because I am part of my own

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group, I belong to my own group. I could change

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that to a different group. But since I'm a regular

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user, not a super user, I won't be able to change

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that permission to any other group. The only person

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or the only account that could change that

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ownership is root, so let's become root su-.

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Once you log in, you do pwd and here it will bring

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you into /root. Now remember you are not in

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your home directory, you are in root directory

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because you are root right now. So I want you to

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go to your home directory, which is, if you remember

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slash home and slash your username. It will take

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you to your home directory. You could just do pwd

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to confirm and do ls -ltr to confirm another

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time that these are your directories and files. If

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you want to change the permission of lisa and you

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wanted to change it from yourself and you want it

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to have this owned by root, what you will do is

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chown and if you specify the name of the user

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you want to change to and the name of the file,

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lisa and then when you do ls -ltr, there you

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will see right here,

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the file is now owned by root.

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You could also do, just to be more specific, so you

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don't see all of the files you do ls -l lisa,

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and you will see here now the file is owned by

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root. You could do the same thing when you do chgrp which is to

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change the group, you could do the

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group also, there was another group called root, and

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you could do lisa again, and go verify it. And now

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you will see this file lisa is owned by root, and

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and the group who owns this file is also root. Now

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what happened when you become yourself again? How

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do you get out of this root account? You just

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simply type exit, you are logged out, and just

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confirm who you are, yourself, which directory

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you are in, your new home directory, do ls -ltr,

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and you see, there is this file lisa. Now what

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happens if you try to delete this file? Let's see.

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rm lisa. It will tell you remove write protected

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regular of empty file. If you say yes, and do ls

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minus ltr, there you go, it is gone. The reason it

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is gone now, why, is because, when you go one step

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back to your home directory. So your home is right

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now is slash home slash yourself. And when you go

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one step back,

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[No audio]

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you are in just slash home and do ls -l. Here

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you will see the iafzal directory, which is your

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home directory, has the permission of yourself to

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read, write, and execute, meaning anything inside

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of the directory you could read, you could write,

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and then you could execute. So regardless if

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whoever puts the file in, whoever owns the file, or

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who whichever groups owns it, you could go ahead

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and still delete it. Now, if you try to create a

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file in, let's say, etc, and you go touch test

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[No audio]

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and you call touch

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[No audio]

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testfile. It will tell you Permission denied because

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you do not have permission to write to this file.

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How do you check that, you do ls -l /. You

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could do that, or you could simply go to cd slash

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and do ls -l. And you'll see here's a list of

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all the directories that are inside of slash. And

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the one we were trying to go to is etc. If you

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notice here, etc is owned by root and the group

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is owned by root as well. Now the root has the

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permission to write to it. But what about the

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people who are in roots group, they don't have

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permission to write to it. What about everybody

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else, they don't have a permission to write to it.

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So that is why you cannot create a file in etc.

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So let's say if you become root again.

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[No audio]

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Okay, and now you go to etc, and you create a file

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touch test123, just verify it, ls -ltr. You

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see at the bottom is your file. Now another way

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what you could do is while we are working on this,

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you could minimize this window and you could open

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another window by right clicking and create Open

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Terminal. So this way we have a regular account

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which is our account and the root account. So this

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way we don't have to exit out of all accounts. So

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we are here, iafzal, which directory we are in

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we are in slash home and we created the file in

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etc right as a root. So let's go to etc, and

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let's see ls -ltr, and now we're going to

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try to remove this file test123, and it's gonna

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say remove right protected. It's just a warning

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usage. Yes. And it still says Permission denied

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now. Why it's saying Permission denied again,

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you go to a cd slash name, and you do ls -l.

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And you will see right here, that says etc

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directory, and it tells you right here, that

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group, three bits do not have write permission.

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And the other three bits do not have the right

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permission as well. So that's how you change the

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user of the files, ownership and group ownerships

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So the two commands that we learned is changed

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ownership, which is chonw, sorry, own, and

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the second one is changed group, chgrp. So again, really

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want you to do a man on each command and go over

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the description, the different options, it has.

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Same thing you do with the second command as well.

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And also, I want you to practice this command by

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changing the permission only in your home

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directory. So your home directory is slash home

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slash yourself and you could try changing

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permission to one of the directory like create a

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new file, don't touch the file that you created

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and just the permission, testfile, create this

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file and just practice your chown and

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chgrp command on this file and see how you could change it.

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[No audio]