Today, I learned from Joany, a fellow Mepis user at the Mepis Community Forums, this nice trick to make files immutable. She says:
"Occasionally, changes to a configuration file that are done manually won't "stick" because a process resets those changes back to default values. Changing file permissions to "read only" does not work when root owns the file and the process making the change."
If you make the file immutable, then nothing or no one will change it, not even root.
So, how does it work? You just have to enter as root this command:
chattr +i filename
If you need to alter the file in the future, the code below will return your file to its normal properties:
chattr -i filename
Hehe! I'm eager to try this trick with the next immutable malware file that gets into my USB pendrive! Thank you, Joany!