Killing Emacs means ending the execution of the Emacs process. If you started Emacs from a terminal, the parent process normally resumes control. The low-level primitive for killing Emacs is
command kill-emacs \&optional exit-data
This command calls the hook
kill-emacs-hook, then exits the Emacs process and kills it.
exit-data is an integer, that is used as the exit status of the Emacs process. (This is useful primarily in batch operation; see Batch Mode.)
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.
exit-data is neither an integer nor a string, or is omitted, that means to use the (system-specific) exit status which indicates successful program termination.
kill-emacs function is normally called via the higher-level command
C-x C-c (
save-buffers-kill-terminal). See Exiting in The GNU Emacs Manual. It is also called automatically if Emacs receives a
SIGHUP operating system signal (e.g., when the controlling terminal is disconnected), or if it receives a
SIGINT signal while running in batch mode (see Batch Mode).
This normal hook is run by
kill-emacs, before it kills Emacs.
kill-emacs can be called in situations where user interaction is impossible (e.g., when the terminal is disconnected), functions on this hook should not attempt to interact with the user. If you want to interact with the user when Emacs is shutting down, use
kill-emacs-query-functions, described below.
When Emacs is killed, all the information in the Emacs process, aside from files that have been saved, is lost. Because killing Emacs inadvertently can lose a lot of work, the
save-buffers-kill-terminal command queries for confirmation if you have buffers that need saving or subprocesses that are running. It also runs the abnormal hook
user option kill-emacs-query-functions
save-buffers-kill-terminal is killing Emacs, it calls the functions in this hook, after asking the standard questions and before calling
kill-emacs. The functions are called in order of appearance, with no arguments. Each function can ask for additional confirmation from the user. If any of them returns
save-buffers-kill-emacs does not kill Emacs, and does not run the remaining functions in this hook. Calling
kill-emacs directly does not run this hook.