ack.vim

let g:ack = "ack -H"

function! s:ack(cmd,args)
    let grepprg_bak = &grepprg
    try
        let &grepprg = g:ack
        silent execute a:cmd . ' ' . a:args
    finally
        let &grepprg = grepprg_bak
    endtry
    "cwindow
endfunction
 
command! -nargs=* -bang -bar -complete=file Ack call s:ack('grep<bang>',<q-args>)
command! -nargs=* -bang -bar -complete=file AckAdd call s:ack('grepadd<bang>',<q-args>)
command! -nargs=* -bang -bar -complete=file LAck call s:ack('lgrep<bang>',<q-args>)
command! -nargs=* -bang -bar -complete=file LAckAdd call s:ack('lgrepadd<bang>',<q-args>)