title: using gitignore to ignore (but not delete) files
body: <p>I have a tmp directory in my git repo I'd like to still exist, but be ignored.  I added it to <code>.gitignore</code>, but <code>git status</code> still tells me about changes to files in that directory.  I tried <code>git rm -r --cached</code>, but that removes it from the remote repo.  How can I stop tracking changes to this directory, but still allow it to exist?  I also need to do this for 1 file, but changes to that also show up in <code>git status</code> after <code>.gitignore</code>ing them.  What should I do?</p>