# is x grep argument available?
  grep-flag-available() {
      echo | grep $1 "" >/dev/null 2>&1
  }

  GREP_OPTIONS=""

  # color grep results

  if grep-flag-available --color=auto; then
      GREP_OPTIONS+=" --color=auto"
  fi

  
  # ignore VCS folders (if the necessary grep flags are available)

  VCS_FOLDERS="{.bzr,CVS,.git,.hg,.svn}"

  
  if grep-flag-available --exclude-dir=.cvs; then
      GREP_OPTIONS+=" --exclude-dir=$VCS_FOLDERS"
  elif grep-flag-available --exclude=.cvs; then
      GREP_OPTIONS+=" --exclude=$VCS_FOLDERS"
  fi
  
  # export grep settings
  alias grep="grep $GREP_OPTIONS"
  
  # clean up
  unset GREP_OPTIONS
  unset VCS_FOLDERS
  unfunction grep-flag-available