Using this file permission pcncept, you can do certain tasks:-

a)chomd: Change the permission of the file

Eg: Create a file with any name and type ls -l then you will see this permission

drwxr-x---

Here r will be considered as "Read", w as "Write" and x as "Execute".

I'll explain this example, what it defines.

d -> stands for directory

rwx -> userr-x -> group

And the last part is the other user

Eg: -rw-rw-r-- 1 ubuntu ubuntu 43 Sep 6 07:45 testing.txt

In this example, - stands for file

rw- : which means user can only read and write a file

rw-: which means group can only read and write a file.

r--: which means other user can only have read permission for that file.

Now I want to give Read permission to user, Write and Execute permission to the group and no permission to other user

ubuntu@ip-172-31-25-118:~$ sudo chmod 430 testing.txt

Output: -r---wx--- 1 ubuntu ubuntu 43 Sep 6 07:45 testing.txt

b)chown: Change the ownership or a user permission of the file

Consider this directory has a owner 'ubuntu'

drwxrwxr-x 4 ubuntu ubuntu 4096 Sep 6 07:14 A

To change the owner you can use below syntax

chown <new-owner-name> <filename/directoryname>

ubuntu@ip-172-31-25-118:~$ sudo chown daya A

Output: drwxrwxr-x 4 daya ubuntu 4096 Sep 6 07:14 A

c)chgrp: Change the group permission of the file.

Consider there is a group called devops which contains the user's like daya and jethalal

Eg devops:x:1002:daya,jethalal

drwxrwxr-x 4 daya ubuntu 4096 Sep 6 07:14 A

I want devops group need to access the directory 'A' instead of ubuntu group

Syntax: chgrp <new-group-name> <filename/directoryname>

Eg: ubuntu@ip-172-31-25-118:~$ sudo chgrp devops A

drwxrwxr-x 4 daya devops 4096 Sep 6 07:14 A

It means that user's like daya and jethalal can able to access the 'A' directory because we have given an access to a group called 'devops'.

File Permission