Immutable File Permissions

Chattr is a command that can be used to set file attributes that can prevent all users (even root) from deleting a file.


Viewing Immutable permissions

lsattr file
Example output of immutable file: 
----i---------- filename

Setting file attributes with chattr

To prevent everyone (even root) from deleting a file: 

chattr +i file
This will now make the file 'read-only'.


To undo this: 

chattr -i file


Restricting Editable files

You can use the +a attribute to allow users to append information into a file only: 

chattr +a