$ curl cheat.sh/
# 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

$
Follow @igor_chubin cheat.sh tldr