Detect If You Are On A Mac

There are a couple ways of detecting with vimscript if you are on a mac. This can be useful if you are writing a plugin with OS-specific functionality. Here are two ways to make that check.

if has('macunix') || has('mac') || has('osx')
  ...
endif

Alternatively, you can use Vim's system() function to execute unix's uname command. This command will give you the name of the operating system. In the event you are using a Mac, the result of uname should be Darwin. The following regex match is a good way to make this check.

if system('uname') =~ "Darwin"
  ...
endif

See :h has(), :h system(), and man uname for more details.