Commit 62a5303f authored by Eli Zaretskii's avatar Eli Zaretskii
Browse files

(Suspending Emacs): Update for multi-tty; document `suspend-tty',

`resume-tty', and `controlling-tty-p'.
parent 2b6ae648
......@@ -577,6 +577,11 @@ 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 @code{fg}.
@cindex controlling terminal
Suspending works only on a terminal device from which the Emacs
session was started. We call that device the @dfn{controlling
terminal} of the session.
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.
......@@ -592,6 +597,13 @@ This function stops Emacs and returns control to the superior process.
If and when the superior process resumes Emacs, @code{suspend-emacs}
returns @code{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
@code{suspend-tty} (@pxref{Visibility of Frames}). If the Emacs
session uses more than one terminal device, you will need to delete
the frames on all the other devices before suspending Emacs, otherwise
this function signals an error.
If @var{string} is non-@code{nil}, its characters are sent to be read
as terminal input by Emacs's superior shell. The characters in
@var{string} are not echoed by the superior shell; only the results
......@@ -663,6 +675,47 @@ This variable is a normal hook that Emacs runs on resuming
after a suspension.
@end defvar
@defun suspend-tty &optional tty
If @var{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. If @var{tty} is a frame, it means that
frame's terminal; if it is @code{nil}, the function uses the selected
frame's terminal. If @var{tty} is already suspended, the function
does nothing.
This function runs the hook @code{suspend-tty-functions} (each
function gets one argument, the terminal that corresponds to
@end defun
@defun resume-tty &optional tty
Resume the previously suspended terminal device @var{tty}. If
@var{tty} is a frame, it means resume that frame's terminal;
@code{nil} means 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 @code{resume-tty-functions}, passing each function the terminal
which corresponds to @var{tty}.
If the same device is already used by another Emacs terminal, this
function signals an error.
@end defun
@defun controlling-tty-p &optional terminal
This function returns non-@code{nil} if @var{terminal} is the
controlling terminal device of the Emacs session.
@end defun
@deffn Command suspend-frame
This command @dfn{suspends} a frame. For GUI frames, it calls
@code{iconify-frame} (@pxref{Visibility of Frames}); for text-only
frames, it calls either @code{suspend-emacs} or @code{suspend-tty},
depending on whether the frame is displayed on the controlling
terminal device or not.
@end deffn
@node System Environment
@section Operating System Environment
@cindex operating system environment
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