I recall a case-insensitivity bug from the early days of Mac OS X.

There are three command-line utilities that are distributed as part of the Perl HTTP library: GET, HEAD, and POST. These are for performing the HTTP operations of those names from the command line.

But there’s also a POSIX-standard utility for extracting the first few lines of a text file. It’s called head.

I think you see where I’m going with this. HEAD and head are the same name in a case-insensitive filesystem such as the classic Mac filesystem. They are different names on a Unix-style filesystem.

Installing /usr/bin/HEAD from libwww-perl onto a Mac with the classic filesystem overwrote /usr/bin/head and broke various things.