— Command: suspend-emacs &optional 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.

This function works only on the controlling terminal of the Emacs session; to relinquish control of other tty devices, use suspend-tty (see below). If the Emacs session uses more than one terminal, you must delete the frames on all the other terminals before suspending Emacs, or this function signals an error. See Multiple Terminals.

If string is non-nil, its characters are sent to Emacs's superior shell, to be read as terminal input. 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 Hooks.

The next redisplay after resumption will redraw the entire screen, unless the variable no-redraw-on-reenter is non-nil. See Refresh 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 canceled")))))
               ⇒ (lambda nil
                    (or (y-or-n-p "Really suspend? ")
                        (error "Suspend canceled")))
          (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.

— Function: suspend-tty &optional tty

If tty specifies a terminal device used by Emacs, this function relinquishes the device and restores it to its prior state. Frames that used the device continue to exist, but are not updated and Emacs doesn't read input from them. tty can be a terminal object, a frame (meaning the terminal for that frame), or nil (meaning the terminal for the selected frame). See Multiple Terminals.

If tty is already suspended, this function does nothing.

This function runs the hook suspend-tty-functions, passing the terminal object as an argument to each function.

— Function: resume-tty &optional tty

This function resumes the previously suspended terminal device tty; tty can be a terminal object, a frame (meaning the terminal for that frame), or nil (meaning the terminal for the selected frame).

This function reopens the terminal device, re-initializes it, and redraws its with that terminal's selected frame. It then runs the hook resume-tty-functions, passing the terminal object as an argument to each function.

If the same device is already used by another Emacs terminal, this function signals an error.

— Function: controlling-tty-p &optional terminal

This function returns non-nil if terminal is the controlling terminal of the Emacs session; terminal can be a terminal object, a frame (meaning the terminal for that frame), or nil (meaning the terminal for the selected frame).

— Command: suspend-frame

This command suspends a frame. For GUI frames, it calls iconify-frame (see Visibility of Frames); for text-only frames, it calls either suspend-emacs or suspend-tty, depending on whether the frame is displayed on the controlling terminal device or not.