chattr

Change attributes of files or directories. More information: https://manned.org/chattr.

Make a file or directory immutable to changes and deletion, even by superuser:

chattr +i {{path/to/file_or_directory}}

Make a file or directory mutable:

chattr -i {{path/to/file_or_directory}}

Recursively make an entire directory and contents immutable:

chattr -R +i {{path/to/directory}}