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8.8 Yes or No Prompts

An Emacs command may require you to answer a yes-or-no question during the course of its execution. Such queries come in two main varieties.

For the first type of yes-or-no query, the prompt ends with ‘(y or n)’. Such a query does not actually use the minibuffer; the prompt appears in the echo area, and you answer by typing either ‘y’ or ‘n’, which immediately delivers the response. For example, if you type C-x C-w (write-file) to save a buffer, and enter the name of an existing file, Emacs issues a prompt like this:

     File ‘foo.el’ exists; overwrite? (y or n)

Because this query does not actually use the minibuffer, the usual minibuffer editing commands cannot be used. However, you can perform some window scrolling operations while the query is active: C-l recenters the selected window; C-v (or <PageDown> or <next>) scrolls forward; M-v (or <PageUp>, or <prior>) scrolls backward; C-M-v scrolls forward in the next window; and C-M-S-v scrolls backward in the next window. Typing C-g dismisses the query, and quits the command that issued it (see Quitting).

The second type of yes-or-no query is typically employed if giving the wrong answer would have serious consequences; it uses the minibuffer, and features a prompt ending with ‘(yes or no)’. For example, if you invoke C-x k (kill-buffer) on a file-visiting buffer with unsaved changes, Emacs activates the minibuffer with a prompt like this:

     Buffer foo.el modified; kill anyway? (yes or no)

To answer, you must type ‘yes’ or ‘no’ into the minibuffer, followed by <RET>. The minibuffer behaves as described in the previous sections; you can switch to another window with C-x o, use the history commands M-p and M-n, etc. Type C-g to quit the minibuffer and the querying command.