title: Running gvim from MSYS --- how to avoid/change MSYS enviroment variables?
body: <p>When I run <code>gvim</code> from MSYS, things go wrong during initialization.  Namely, <code>gvim</code> can't find the initialization files that are in '<code>C:\Documents and Settings\username\vimfiles</code>.</p>
  
  <p>[Specifically, gvim reports the error <code>E117: Unknown function: pathogen#infect</code> during initialization, so it never found <code>autoload\pathogen.vim</code>.  Doing <code>:scriptnames</code> also confirms that none of the setup files from <code>vimfiles\</code> are run.]</p>
  
  <p>I think I've debugged why it goes wrong.  When you start MSYS, the MSYS shell inherits the windows enviroment variables, but changes some of them to it's custom values.  <code>C:\Documents and Settings\username</code> is the value of <code>$HOME</code> in Windows, but MSYS sets it to something like <code>C:/msys/user name</code>.  And of course, Vim uses <code>$HOME</code> to find the right initialization files.</p>
  
  <p>I also notice <code>set shell?</code> has changed to something like <code>shell=C:/msys/bin/sh</code> instead of <code>shell=C:\WINDOWS\system32\cmd.exe</code>, but I hope this isn't important for fixing the initialization problem.</p>
  
  <p>I need to run gvim with the normal windows environment variables.  At least I need to be able to manually override a few important ones like <code>$HOME</code> to something I specify (i.e., I'm not concerned about my windows <code>$HOME</code> changing, so it's fine to use a static value).  </p>
  
  <p>I tried to reset <code>$HOME</code> manually in my vimrc, but by then it is too late.</p>
  
  <p>Is there some trick to specifying <code>$HOME</code> early on during initialization, or as an extra command line parameter?</p>
  
  <p>Alternatively, is there some trick with running commands from <code>msys</code> differently?  I know almost nothing about how the shell <code>C:/msys/bin/sh</code> works, but I could conceive of some extra arguments that changes the visibile environment for the command (e.g. <code>gvim.exe</code>) you are typing.</p>
  
  <p><strong>---Edit---</strong><br>
  Reposting the solution that worked (it achieves the later idea):  </p>
  
  <p>Instead of running <code>gvim.exe</code>, run the command <code>HOME="C:\Documents and Settings\username" gvim.exe</code></p>