40.2.2 Suspending Emacs

Suspending Emacs means stopping Emacs temporarily and returning control to its superior process, which is usually the shell. This allows you to resume editing later in the same Emacs process, with the same buffers, the same kill ring, the same undo history, and so on. To resume Emacs, use the appropriate command in the parent shell--most likely fg.

Some operating systems do not support suspension of jobs; on these systems, "suspension" actually creates a new shell temporarily as a subprocess of Emacs. Then you would exit the shell to return to Emacs.

Suspension is not useful with window systems, because the Emacs job may not have a parent that can resume it again, and in any case you can give input to some other job such as a shell merely by moving to a different window. Therefore, suspending is not allowed when Emacs is using a window system (X or MS Windows).

Function: suspend-emacs string

This function stops Emacs and returns control to the superior process. If and when the superior process resumes Emacs, suspend-emacs returns nil to its caller in Lisp.

If string is non-nil, its characters are sent to be read as terminal input by Emacs's superior shell. The characters in string are not echoed by the superior shell; only the results appear.

Before suspending, suspend-emacs runs the normal hook suspend-hook.

After the user resumes Emacs, suspend-emacs runs the normal hook suspend-resume-hook. See section 23.6 Hooks.

The next redisplay after resumption will redraw the entire screen, unless the variable no-redraw-on-reenter is non-nil (see section 38.1 Refreshing the Screen).

In the following example, note that `pwd' is not echoed after Emacs is suspended. But it is read and executed by the shell.

(suspend-emacs) => nil (add-hook 'suspend-hook (function (lambda () (or (y-or-n-p "Really suspend? ") (error "Suspend cancelled"))))) => (lambda nil (or (y-or-n-p "Really suspend? ") (error "Suspend cancelled"))) (add-hook 'suspend-resume-hook (function (lambda () (message "Resumed!")))) => (lambda nil (message "Resumed!")) (suspend-emacs "pwd") => nil ---------- Buffer: Minibuffer ---------- Really suspend? y ---------- Buffer: Minibuffer ---------- ---------- Parent Shell ---------- lewis@slug[23] % /user/lewis/manual lewis@slug[24] % fg ---------- Echo Area ---------- Resumed!

Variable: suspend-hook

This variable is a normal hook that Emacs runs before suspending.

Variable: suspend-resume-hook

This variable is a normal hook that Emacs runs on resuming after a suspension.