Case sensitivity in Mac OS X does not exist.
The OS X command line is probably the most commonly used feature of my MacBook Pro. I love the fact that almost all the Linux commands I'm used to using on a Linux box work the same way in OS X. So, as you can imagine, I was shocked when I couldn't rename a simple directory:
eris:~ raam$ mv Downloads/ downloads/
mv: cannot move `Downloads' to a subdirectory of itself, `downloads/Downloads'
That command should allow me to rename 'Downloads' to 'downloads', but apparently OS X thinks 'Downloads' and 'downloads' are the same thing! That's absurd! In the Unix world, case matters!
So how did I eventually rename it?
eris:~ raam$ mv Downloads/ downloads2/
eris:~ raam$ mv downloads2/ downloads/
That's just ridiculous.
I installed the Fluxbox window manager on my MacBook Pro a while back and decided to start it up to make sure I had access to a "real" command line. Sure enough, the command worked as expected within Fluxbox. Maybe I'll start using Fluxbox a lot more often.
Check out this snippet from an article on InformIT:
Mac OS X, like the classic Mac OS before it, is not case sensitive; it doesn't care whether you said File1.txt or file1.txt. Only one of them can exist in a folder at the same time, and there's no ambiguity for either computers or humans in telling which file you meant. Even Unix commands like ls will work if you give them filenames to operate on that don't match the capitalization of the actual files (try it: ls /library).
That's really quite disappointing. I have suddenly lost so much respect for the OS X command line. Being derived from BSD in the Unix world, you would think Apple would keep something as fundamental as case sensitivity in OS X.