title: Have same vifm configuration file for both OSX and linux systems
body: <p>I recently started using vifm and having a solid background in vim, I am excited about the capabilities this file manager offers!</p>
  
  <p>I use vifm both in my host OSX system and in my Linux vm. How can I have both configurations in the same rc file? Is there any if-clause that can be used to identify the os and run a set of commands based on it? (e.g the file opening commands differ from OSX, where a single "open -g %f" opens the file with the correct application and in Linux where you have to explicitly assign programs to the corresponding filetypes)</p>
  
  <p>I tried the following vim block of commands but without any luck:</p>
  
  <pre><code>let os = substitute(system('uname'), "\n", "", "")
  if os == "Darwin"
      let a = "kalinuxta"
  elseif os == "Linux"
      let a = "kalimera"
  endif
  </code></pre>