Types of permissions
r - read 4
w - write 2
x - execute 1
Permission (rwx) levels
u - yourself (the current user)
g - group to which the user belong to
o - others (outside the group)
a - all
How to see the permissions?
ls -ltr
find group information
id <user_name>
How to change the permission?
chmod u+r <file_name> (for adding permission)
chmod u-r <file_name> (for removing permission)
chmod ugo+r <file_name>
chmod ugo-r <file_name>
chmod a+rwx <file_name> (adding the permission for all)
chmod a-rwx <file_name> (for removing all the permission)
chmod g+rw <file_name> (for adding permission to group)
Note: one more important thing is you can't change other user permission it means when u logged in to Safia user but change the permission of the root user then you can't but the root user can change all permission of other users but normal users can't.
chmod Numeric Mode
Ex : chmod 756 <file_name>
so here,
The first numeric number 7 shows the user
The second numeric number 5 shows the group
The Third numeric number 6 shows the other user
Number Permission Type Symbol
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
Access Control List (ACL)
What is ACL?
It allows you to give a more specific set of permissions to a file or directory without changing the base ownership and permission.
Commands : setfacl & getfacl
getfacl:- The getfacl command displays the access permissions of files and directories with file name, owner, group and the ACLs (Access Control List).
getfacl<file_name>
setfacl
For adding permission for the user
setfacl -m u:user_name:rwx <target_file>
For adding the permission for group
setfacl -m:g:group_name:rwx <target_file>
To remove a specific entry
setfacl -x u:user_name:rwx <target_file>
To remove all entries
setfacl -b <target_file>
where,
-m - modification
-x - remove permission
-b - remove all entries
For adding permissions for the user in all the files inside a folder - (it means only one user to permit to access the file/folder)
setfacl -Rm "entry" <targetfile/folder>
ex : setfacl -Rm u:safia:rwx my_folder
File Ownership Commands
chown: To change user ownership.
chgrp: To change group ownership.
sudo chown -c Safia test_file
sudo chgrp -c Dev_Safia test_file
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