write the output of a global command to a file in vim code example

Example: write the output of a global command to a file in vim

function! OutputSplitWindow(...)
  " this function output the result of the Ex command into a split scratch buffer
  let cmd = join(a:000, ' ')
  let temp_reg = @"
  redir @"
  silent! execute cmd
  redir END
  let output = copy(@")
  let @" = temp_reg
  if empty(output)
    echoerr "no output"
  else
    new
    setlocal buftype=nofile bufhidden=wipe noswapfile nobuflisted
    put! =output
  endif
endfunction
command! -nargs=+ -complete=command Output call OutputSplitWindow(<f-args>)