how do I detect OS X in my .vimrc file, so certain configurations will only apply to OS X?

I use my .vimrc file on my laptop (OS X) and several servers (Solaris & Linux), and could hypothetically someday use it on a Windows box. I know how to detect unix generally, and windows, but how do I detect OS X? (And for that matter, is there a way to distinguish between Linux and Solaris, etc. And is there a list somewhere of all the strings that 'has' can take? My Google-fu turned up nothing.)

For instance, I'd use something like this:

if has("mac")
  " open a file in TextMate from vi: "
  nmap mate :w<CR>:!mate %<CR>
elseif has("unix")
  " do stuff under linux and "
elseif has("win32")
  " do stuff under windows "
endif

But clearly "mac" is not the right string, nor are any of the others I tried.

---

UPDATE: The answer below ("macunix") seems fairly clearly like it should work, but for some reason it doesn't. (Perhaps Apple didn't compile vim properly to respond to this? Seems unlikely.)

At any rate I guess I need to shift the focus of the question: does anyone have a solution that will achieve the same ends? (That is, successfully detecting that the .vimrc file is being used on Mac OS X.)

My updated .vimrc now uses the following:

if has("gui_running")
  " Gvim
  if has("gui_gtk2") || has("gui_gtk3")
    " Linux GUI
  elseif has("gui_win32")
    " Win32/64 GVim
  elseif has("gui_macvim")
    " MacVim
  else
    echo "Unknown GUI system!!!!"
  endif
else
  " Terminal vim
endif

My original answer is below

---

You could try what I do in my .vimrc:

if has("unix")
  let s:uname = system("uname -s")
  if s:uname == "Darwin"
    " Do Mac stuff here
  endif
endif

Although, to be completely transparent, my actual .vimrc reads:

let s:uname = system("echo -n \"$(uname)\"")
if !v:shell_error && s:uname == "Linux"

Mainly for detecting Linux (as opposed to OSX)

I'm not sure if you absolutely have to do that echo -n \"$(uname)\" stuff, but it had to do with the newline at the end of the uname call. Your mileage may vary.

I could not edit previous answer by adding two character only:

Here is correct one(passed on my macos 10.6 and default vim console version)

if has("unix")
  let s:uname = system("uname")
  if s:uname == "Darwin\n"
    " Do Mac stuff here
  endif
endif

system("uname") will come up with a return character, which makes second if condition failed. Just a small fix to add "\n".

I'm doing the same thing you are. Don't try to detect the OS. Instead, try to detect the type of vi/vim.

Check :h feature-list for a full list of the conditionals you can use.

Here's what I use to detect MacVim in my vimrc:

if has("gui_macvim")
  set guifont=Monaco:h13
endif

With this, you can detect for gvim, vi, vim, and whatever other flavors you might use. The nice thing is that you could have vim-compatible settings on OS X.

Reference from Vim Mailing list

EDIT: This approach and its variants (has('mac'), has('macunix'), has('gui_mac'))do not work for vim in OS X. If you use only use MacVim, you're safe. If you're weird like me and like to occasionally jump into vim, one of the other solutions may be more suitable.

homebrew vim and MacVim returns true for has('mac'), however so does has('unix'). so to have it work across all unix platforms, a possible solution is:

if has('unix')
  if has('mac')       " osx
    set guifont=...
  else                " linux, bsd, etc
    set guifont=...
  endif
elseif has('win32') || has('win64')
  set guifont=...
endif

on the other hand, as of el capitan, the system vim returns false for has('mac'), and uname snooping is probably the way to go. it's an ancient version, never used it.

You want macunix. To quote :h feature-list:

mac		Macintosh version of Vim.
macunix	Macintosh version of Vim, using Unix files (OS-X).

mac, AFAIK, only applies to old-school Macs, where \r is the line separator.

This is the easiest way I have found.

if system('uname -s') == "Darwin\n"
  "OSX
  set clipboard=unnamed 
else
  "Linux
  set clipboard=unnamedplus
endif

gui_macvim gui_gtk2 gui_gtk gui_win32

There is a OS detection script somewhere on stackoverflow - more keywords to find it: win64 win95 macunix...