:Capture - Capture output of ex command.

.vimrc

" Capture {{{
function! s:get_output(...) "{{{
    " a:000 = [['echo', '"foo"'], 'messages', ...]
    "
    " TODO nested :redir ?

    redir => output

    for cmd_args in a:000
        if type(cmd_args) == type([])
            silent execute join(cmd_args)
        else
            silent execute cmd_args
        endif
    endfor

    redir END
    return substitute(output, '^\n\n', '', '')
endfunction "}}}



AlterCommand cap[ture] Capture

command!
\   -nargs=+ -complete=command
\   Capture
\   call s:cmd_capture(<q-args>)

function! s:cmd_capture(q_args) "{{{
    let out = s:get_output(a:q_args)    " NOTE: Execute ex command in current buffer.
    New    " Change as you like. for e.g., :new instead.
    silent file `=printf('[Capture: %s]', a:q_args)`
    setlocal buftype=nofile bufhidden=unload noswapfile nobuflisted
    call setline(1, split(out, '\n'))
endfunction "}}}
" }}}