The reason their side-effects are unexpected is not that ACLs are intrinsically weird, it&#x27;s that very few people have familiarity with day-to-day use of ACLs on Unix. The reason that very few people have familiarity with day-to-day use of ACLs on Unix is that very few people use them. The reason that very people use them is because very few people are familiar with them. It&#x27;s a bit of a Catch-22.<p>For other ways to completely baffle your users, have a play with file attributes:<p><a href="http:&#x2F;&#x2F;linux.die.net&#x2F;man&#x2F;1&#x2F;chattr" rel="nofollow">http:&#x2F;&#x2F;linux.die.net&#x2F;man&#x2F;1&#x2F;chattr</a>