Types of file Permission
Basic Permission
Special Permission
ACL ( Acess Control List) permission
Permission details
Permission Description
Owner (U) : Permission user for the owner of the file.
Group ( g) : Permission used by members of the group.
Others (o) : Permission used by others users.
Permission Set
Read : This permission give you the authority to open and read a file.
Write : The write permission gives you the authority to modify the contents of a file.
Execute : Executable Permission, which the user may run the program if it is executable.
Permission with Numeric and symbol
| Number | Permission Type | Symbole |
| 0 | No Permission | - - - |
| 1 | Execute | - - x |
| 2 | Write | - w - |
| 3 | Execute + Write | - wx |
| 4 | Read | r -- |
| 5 | Read + Execute | r-x |
| 6 | Read + Write | rw- |
| 7 | Read + Write + Execute | rwx |
Note : You can control all of the permissions if you can only remember three of them by adding these numbers. Eg. if you need read and write permission the value is 4+2=6.
r (read): 4
w (write): 2
x (execute): 1
Change the permission with a Numeric value
change the permission for a file called text.txt
Full access to Owner
Read Execute Permission to Group
Execute permission to others
chmod 751 /test.txtCheck the directory permission for dev folder
ls -ld /devCheck the permission of the file test1.txt
ls -l /test1.txt
Changing Permission of files
Add the read permission to the Owner group of the file test.txt file
chmod u+r /test.txtAdd the read write permission to Group of file name called test2.txt
chmod g+rw /test2.txtRemove the read permission from the group Others of the file name called test.txt
chmod o-r /test.txt
Changing the ownership
Syntax: chown <user name > <File/Directory Name>
Changing the ownership to a new user named mbubur of the file name called test.txt
chown mbubur
Changing the Group ownership
Syntax: chgrp <group name> <file / directory name >
Change the group ownership to mbubur user of the file called test.txt
chgrp mbubur /test.txt
Access Control List (ACL)
A list of permissions attached to an object that specifies which users or groups are granted access to that object and what actions they are allowed to perform. Access control lists are commonly used in computer security to control access to files, folders, and other resources.
Use of ACL:
In computer security, an ACL can be used to control access to files, folders, and other resources. For example, a system administrator might create an ACL that grants read access to a certain file for a particular group of users, while denying access to all other users.
For checking ACL permission
Syntax: getfacl <file / directory name >
Check the ACL for Directory named devops
getfacl /devops
Set ACL permission to the user mbubur to the group devops
setfacl -m u:mbubur:rwx /devops
Remove ACL permission for the user mbubur from devops group
setfacl -x u:mbubur: /devops
Set the ACL permission for the Group called devops
setfacl -m g:testgrp:rwx /devops
Remove the ACL permission for the Group called devops
setfacl -x g:testgrp: /devops
Remove all permission
setfacl -b /devops