Linux - Set file permission using octal

So hope you have understood how to change the permission by using this symbolic method

Now let us begin to change the permission by using an octal numbers

Same way like you have used operators into the previous video to change the permission

Here we will be using the numbers. So basically the octal numbers start from 0 till 7

It means 0 to 7. That means it is 8. So these all 8 numbers we can use for setting the permissions to your file or a directory

or a directory. Now very first you can see 0. If I define 0 means there is no permission closely

So you can see here into the group we do not have any permission, neither read, write or execute

Same way we use 1. 1 is reserved for your execute permission

So if I want to define any execute permission, I'll just define the permission as 1

So it will take it as no read, no right and just execute, hyphen, hyphen x

same way if we use 2 is reserved for your right formation

so basically if I want to define only right formation to a particular group

I can use 2 as a permission so it will provide you

hyphen w and hyphen the next we have number 3 so basically this 3 is not reserved

this 3 is addition of your 1 and 2 so where the 1 is your execute permission and 2 is your right permission

So if I define number 3, it will calculate your 2 and 1 and it will make it 3 where it will provide you the permission as read and execute

Basically it will provide you the permission as write and execute. So you can find here no read but you have write and execute permission

The next we have that is 4. 4 is completely reserved for your read permission

So if you want to specify a read permission, you'll just define the group as a number 4

So it will provide you only read without write and execute. Same this is you have that is 5

5 means we are going to add this 4 along with this 1. 4 means read permission and while 1 we have that is for execute permission

So if I want to define any particular user or any particular group for the permission as a read and execute

so I just define the number as 5. So it will get the permission as R-hyphen X means no right

right formation now here we have six six again includes your read and right because

six includes four plus two four means read and two means right so you can find

four means rate and two plus right so if I want to define any particular

owner group or others as read and write formation I can give number six So you can see into the attribute we have R but no execute formation

But what if I want to provide the complete access to everything

Means we can say a full control formation. So we'll just have 7

7 means including your read, write and execute. Read, 4, write, 2 and execute 1

So calculating all the 3, adding this 3 will get number 1. this three will get number seven. So if you define the permission as seven, it will directly

take read, write and execute for your group owner or your others. So this is the way how generally

we use octal numbers for defining the formation. So let us see this practically into our Linux

terminal. Now here we can see the number of directory and file we do have into this desktop

So I have to one file and one directory, two content we have

And now I'm going to change the permission of this directory. This is folder 1

So right now the permission which we have for the folder 1 is read, write, execute for the owner

rewrite and execute for the group, and read and execute for the others

Now if I want to set the permission or change the permission using my octal numbers

I'll be giving the owner permission first. Now for example, I want to change the owner permission

to read and write only. So for read, I have the number assigned that is 4 and for

right I have 2. So I'll just add both of it that is 6. And then for group I want to

assign read and execute that is R and X. For read we have 4 and for execute we have 1. So

it will be 5 and I want to define only read permission to my others. So I can define only

Only read permission that is 4. Now I need to define the directory name

Just check it out. Here you can see it's changed. The owner is having read and write group, read and execute while others only read

Same way if I want to change the permission. Read write and execute to my owner so I'll use 7. Read and

execute to my group. So I'll just keep it 5 itself and no permission to others. I'll keep

0 for the same directory folder 1. Check into the allow. Now you have full control for owner

read and execute for the group and nothing for others. So this is how you can change the folder

formation Now I just take an scenario where I have a folder into a folder For example I just move into the folder 1 There is nothing into the folder 1 I going to create a directory into the folder 1

Into folder 1, I'm going to create a directory with name Data 1 and Data 2, for example

Now you can see the permissions which we have for Data 1 and Data 2 is completely different than what we have into the folder 1

into folder 1 we have set the permission as read write and execute for owner read and execute

for the group and for others we haven't defined any permission but you can see this

sub directory which we have created after defining the permission it's containing all together a different permission that it is containing read write and

execute for the owner same the group has the full control permission and the other

has written execute only. That's because Linux is more secure for defining the

permission. Generally even though if it is a parent and child relation

folders or you have the child directories it won't inherit the permission which

we have for the parent directory or by tone. So unlike like where Windows we

need to define the permissions for our child directories as well. So for

defining the child directory permissions what we can do is is we can use the same command CHMode hyphen capital R for recursive

Directors, I'm just going to define the folder name and I'm going to refine the permission

what we require. So I'm going to define the permission 750 even I want for the subfolders of your folder 1

That is data 1 and data 2. And next I'll go inside the directory

folder 1 and we can check the permission of your data 1 and data 2 you can see it almost

inherited the permission which we had on folder 1 but only this is for this two data again if

I create any other directory you will find that it's again containing the default formation

now what is this default formation this default formation this default formation which

generally get by UMass number. So this UMass number we should know

What is the UMass number? It containing 0,002. That means it generally basically get added from 4 times 7 this number that is the UMass number So whatever the number you get So here you will be getting 777 and this minus 2 that is your UMass number That means you have

just we can say you can remove this number and zero. So you have three sevens because this is set for this

special kind of formation we are going to see letter. So right now you have this three seven which we are

using for owner group and other formation and this three digits zero zero two

So if you divide it, you will be getting 7, 7 and then 5

This is the permission of what you get, right? So let us check, is that the same permission we are getting for data 3

7, 7 and 5. So that's the reason because of UMass, you are getting this default permission for each and every directories

Now, how we can change the UMask value? If I want to change the UMask value so that all my directories which I generally create should get 7-50 permission

So for that, I just need to make the UMASC value in such a way. For 7, I'll give 0

For 5, I'll give 2 because it will get subtracted from the 7 itself

So the remaining I'll have that is 5. And for my others, I'll give 7 because from 7 it will be subtracted and we will be able to get

750 right so let us check after creating a directory right now I do have this three

directories and I'm going to add a new directory with name data 4 again check

this directory all together has a different permissions unlike at this directory so here it has read write and execute read and execute and execute and

nothing for your others. That is because of you must know not only on this file but

this will be reflecting all the directories if you create anywhere like even if I've

created on desktop can check for doc one even you have the same permission so read

and execute for your owner read and execute for your other this is a group members

and no permission for your others. So this is how we can manage the file permission using your CH more command and set the UMass

So the default value of UMASC is 000 to itself in any of the distributors

So this is we have seen about the permissions by using the occult permissions

Now we are going to see how we can use the G-O-ID and SUID permissions into the next video