In Emacs, how do I select the completion list with the keyboard?
autocomplete, emacs, minibuffer
Solution
You can use M-v (documented here) which switches to the completion buffer and puts the cursor on the first completion:
Typing M-v, while in the minibuffer, selects the window showing the completion list (switch-to-completions). This paves the way for using the commands below. `<PageUp>` or `<prior>` does the same. You can also select the window in other ways...
EDIT: It looks like based on your edit to the original question that what you're asking for is a way to switch to the completions buffer more globally. There is a function `switch-to-completions` that selects the completions list - you might consider binding that function to a key of your choosing, e.g.:
(define-key global-map (kbd "C-x t") 'switch-to-completions)
For example, such a binding allows me to switch to completions from "Shell command: " invoked by M-!, and places the cursor on the first possible completion.
Problem
When I tab-complete in a minibuffer and Emacs displays a completion list in a new buffer, how do I switch to that buffer without using the mouse? I tried `C-x o`, but that just switched to the first buffer, out of which I entered the minibuffer. I also tried `C-x b`, but that gives me `command attempted to use minibuffer while in minibuffer`. Lastly I tried `C-x <C-right>`, which gives me `cannot switch buffers in minibuffer window`. EDIT: I spoke about minibuffer completion in my example, but being able to access the completion list (using the keyboard) from within a regular buffer is also important to me, and not working. The `M-v` shortcut was suggested, but it only seems to work inside the minibuffer accessed by `M-x`, in every other buffer I've tried, `M-v` is bound to `scroll down command` and does not switch to the completion list. I doesn't even seem to work in other minibuffers. For example, it doesn't work in the shell command minibuffer invoked by `M-!` either.