Killing Emacs means ending the execution of the Emacs process. The
parent process normally resumes control. The low-level primitive for
killing Emacs is
This command exits the Emacs process and kills it.
If exit-data is an integer, then it is used as the exit status of the Emacs process. (This is useful primarily in batch operation; see Batch Mode.)
If exit-data is a string, its contents are stuffed into the terminal input buffer so that the shell (or whatever program next reads input) can read them.
All the information in the Emacs process, aside from files that have
been saved, is lost when the Emacs process is killed. Because killing
Emacs inadvertently can lose a lot of work, Emacs queries for
confirmation before actually terminating if you have buffers that need
saving or subprocesses that are running. This is done in the function
save-buffers-kill-emacs, the higher level function from which
kill-emacs is usually called.
After asking the standard questions,
save-buffers-kill-emacscalls the functions in the list
kill-emacs-query-functions, in order of appearance, with no arguments. These functions can ask for additional confirmation from the user. If any of them returns
save-buffers-kill-emacsdoes not kill Emacs, and does not run the remaining functions in this hook. Calling
kill-emacsdirectly does not run this hook.
This variable is a normal hook; once
save-buffers-kill-emacsis finished with all file saving and confirmation, it calls
kill-emacswhich runs the functions in this hook.
kill-emacsdoes not run this hook in batch mode.
kill-emacsmay be invoked directly (that is not via
save-buffers-kill-emacs) if the terminal is disconnected, or in similar situations where interaction with the user is not possible. Thus, if your hook needs to interact with the user, put it on
kill-emacs-query-functions; if it needs to run regardless of how Emacs is killed, put it on