grepper.vim

" Changing the defaults arguments:

let grepper = {
      \ 'grep': {
      \  'grepprg': 'grep -rn --include=\*.rb $* .'
      \ }}
      
" Set the command on the fly (useful for commands):

command! RubyGrep Grepper -grepprg grep -rn --include=\*.rb $* .

" For a tool like git this is much easier, since you can use the default arguments:

:Grepper -tool git
git grep -nI> up *.rb