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Allow not erase output buffer in shell commands

* lisp/simple.el (shell-command-not-erase-buffer): New option to allow
not erasing the output buffer between shell commands.  Defaults to nil.
(shell-command-on-region): Use it.
(shell-command--save-pos-or-erase): New defun; store a buffer position
if 'shell-command-not-erase-buffer' is non-nil; otherwise
erase the output buffer of the shell command.
(shell-command, shell-command-on-region): Use it.
(shell-command--set-point-after-cmd): New defun;
if 'shell-command-not-erase-buffer' is non-nil, set point
in the output buffer to the position in 'shell-command-saved-pos'.
(shell-command-sentinel, shell-command-on-region): Use it.
* doc/emacs/misc.texi (shell-command-not-erase-buffer):
Document this feature in the manual.
; * etc/NEWS: Add entry for this new feature.
See discussion on:
http://lists.gnu.org/archive/html/emacs-devel/2016-07/msg00610.html
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1 parent 5783984 commit c7119916dc958eeb8e6e2ef50d4a9f262db5be32 @calancha calancha committed Aug 16, 2016
Showing with 107 additions and 18 deletions.
  1. +8 −0 doc/emacs/misc.texi
  2. +10 −0 etc/NEWS
  3. +89 −18 lisp/simple.el
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@@ -771,6 +771,14 @@ the output buffer. But if you change the value of the variable
@code{shell-command-default-error-buffer} to a string, error output is
inserted into a buffer of that name.
+@vindex shell-command-not-erase-buffer
+ By default, the output buffer is erased between shell commands.
+If you change the value of the variable
+@code{shell-command-not-erase-buffer} to a non-@code{nil} value,
+the output buffer is not erased. This variable also controls where to
+set the point in the output buffer after the command completes; see the
+documentation of the variable for details.
+
@node Interactive Shell
@subsection Interactive Subshell
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@@ -56,6 +56,16 @@ affected by this, as SGI stopped supporting IRIX in December 2013.
* Changes in Emacs 25.2
+++
+** The new user option 'shell-command-not-erase-buffer' controls
+if the output buffer is erased between shell commands; if non-nil,
+the output buffer is not erased; this variable also controls where
+to set the point in the output buffer: beginning of the output,
+end of the buffer or save the point.
+When 'shell-command-not-erase-buffer' is nil, the default value,
+the behaviour of 'shell-command', 'shell-command-on-region' and
+'async-shell-command' is as usual.
+
++++
** The new user option 'mouse-select-region-move-to-beginning'
controls the position of point when double-clicking mouse-1 on the end
of a parenthetical grouping or string-delimiter: the default value nil
View
@@ -37,6 +37,27 @@
(defvar compilation-current-error)
(defvar compilation-context-lines)
+(defcustom shell-command-not-erase-buffer nil
+ "If non-nil, output buffer is not erased between shell commands.
+Also, a non-nil value set the point in the output buffer
+once the command complete.
+The value `beg-last-out' set point at the beginning of the output,
+`end-last-out' set point at the end of the buffer, `save-point'
+restore the buffer position before the command."
+ :type '(choice
+ (const :tag "Erase buffer" nil)
+ (const :tag "Set point to beginning of last output" beg-last-out)
+ (const :tag "Set point to end of last output" end-last-out)
+ (const :tag "Save point" save-point))
+ :group 'shell
+ :version "25.2")
+
+(defvar shell-command-saved-pos nil
+ "Point position in the output buffer after command complete.
+It is an alist (BUFFER . POS), where BUFFER is the output
+buffer, and POS is the point position in BUFFER once the command finish.
+This variable is used when `shell-command-not-erase-buffer' is non-nil.")
+
(defcustom idle-update-delay 0.5
"Idle time delay before updating various things on the screen.
Various Emacs features that update auxiliary information when point moves
@@ -3210,6 +3231,53 @@ output buffer and running a new command in the default buffer,
:group 'shell
:version "24.3")
+(defun shell-command--save-pos-or-erase ()
+ "Store a buffer position or erase the buffer.
+See `shell-command-not-erase-buffer'."
+ (let ((sym shell-command-not-erase-buffer)
+ pos)
+ (setq buffer-read-only nil)
+ ;; Setting buffer-read-only to nil doesn't suffice
+ ;; if some text has a non-nil read-only property,
+ ;; which comint sometimes adds for prompts.
+ (setq pos
+ (cond ((eq sym 'save-point) (point))
+ ((eq sym 'beg-last-out) (point-max))
+ ((not sym)
+ (let ((inhibit-read-only t))
+ (erase-buffer) nil))))
+ (when pos
+ (goto-char (point-max))
+ (push (cons (current-buffer) pos)
+ shell-command-saved-pos))))
+
+(defun shell-command--set-point-after-cmd (&optional buffer)
+ "Set point in BUFFER after command complete.
+BUFFER is the output buffer of the command; if nil, then defaults
+to the current BUFFER.
+Set point to the `cdr' of the element in `shell-command-saved-pos'
+whose `car' is BUFFER."
+ (when shell-command-not-erase-buffer
+ (let* ((sym shell-command-not-erase-buffer)
+ (buf (or buffer (current-buffer)))
+ (pos (alist-get buf shell-command-saved-pos)))
+ (setq shell-command-saved-pos
+ (assq-delete-all buf shell-command-saved-pos))
+ (when (buffer-live-p buf)
+ (let ((win (car (get-buffer-window-list buf)))
+ (pmax (with-current-buffer buf (point-max))))
+ (unless (and pos (memq sym '(save-point beg-last-out)))
+ (setq pos pmax))
+ ;; Set point in the window displaying buf, if any; otherwise
+ ;; display buf temporary in selected frame and set the point.
+ (if win
+ (set-window-point win pos)
+ (save-window-excursion
+ (let ((win (display-buffer
+ buf
+ '(nil (inhibit-switch-frame . t)))))
+ (set-window-point win pos)))))))))
+
(defun async-shell-command (command &optional output-buffer error-buffer)
"Execute string COMMAND asynchronously in background.
@@ -3271,7 +3339,8 @@ Noninteractive callers can specify coding systems by binding
The optional second argument OUTPUT-BUFFER, if non-nil,
says to put the output in some other buffer.
If OUTPUT-BUFFER is a buffer or buffer name, erase that buffer
-and insert the output there.
+and insert the output there; a non-nil value of
+`shell-command-not-erase-buffer' prevent to erase the buffer.
If OUTPUT-BUFFER is not a buffer and not nil, insert the output
in current buffer after point leaving mark after it.
This cannot be done asynchronously.
@@ -3408,13 +3477,8 @@ the use of a shell (with its need to quote arguments)."
(setq buffer (get-buffer-create
(or output-buffer "*Async Shell Command*"))))))
(with-current-buffer buffer
- (setq buffer-read-only nil)
- ;; Setting buffer-read-only to nil doesn't suffice
- ;; if some text has a non-nil read-only property,
- ;; which comint sometimes adds for prompts.
- (let ((inhibit-read-only t))
- (erase-buffer))
(display-buffer buffer '(nil (allow-no-window . t)))
+ (shell-command--save-pos-or-erase)
(setq default-directory directory)
(setq proc (start-process "Shell" buffer shell-file-name
shell-command-switch command))
@@ -3497,12 +3561,14 @@ and are only used if a pop-up buffer is displayed."
;; We have a sentinel to prevent insertion of a termination message
-;; in the buffer itself.
+;; in the buffer itself, and to set the point in the buffer when
+;; `shell-command-not-erase-buffer' is non-nil.
(defun shell-command-sentinel (process signal)
- (if (memq (process-status process) '(exit signal))
- (message "%s: %s."
- (car (cdr (cdr (process-command process))))
- (substring signal 0 -1))))
+ (when (memq (process-status process) '(exit signal))
+ (shell-command--set-point-after-cmd (process-buffer process))
+ (message "%s: %s."
+ (car (cdr (cdr (process-command process))))
+ (substring signal 0 -1))))
(defun shell-command-on-region (start end command
&optional output-buffer replace
@@ -3536,7 +3602,8 @@ appears at the end of the output.
Optional fourth arg OUTPUT-BUFFER specifies where to put the
command's output. If the value is a buffer or buffer name,
-erase that buffer and insert the output there.
+erase that buffer and insert the output there; a non-nil value of
+`shell-command-not-erase-buffer' prevent to erase the buffer.
If the value is nil, use the buffer `*Shell Command Output*'.
Any other non-nil value means to insert the output in the
current buffer after START.
@@ -3616,7 +3683,10 @@ interactively, this is t."
(let ((buffer (get-buffer-create
(or output-buffer "*Shell Command Output*"))))
(unwind-protect
- (if (eq buffer (current-buffer))
+ (if (and (eq buffer (current-buffer))
+ (or (not shell-command-not-erase-buffer)
+ (and (not (eq buffer (get-buffer "*Shell Command Output*")))
+ (not (region-active-p)))))
;; If the input is the same buffer as the output,
;; delete everything but the specified region,
;; then replace that region with the output.
@@ -3635,10 +3705,9 @@ interactively, this is t."
;; output there.
(let ((directory default-directory))
(with-current-buffer buffer
- (setq buffer-read-only nil)
(if (not output-buffer)
(setq default-directory directory))
- (erase-buffer)))
+ (shell-command--save-pos-or-erase)))
(setq exit-status
(call-process-region start end shell-file-name nil
(if error-file
@@ -3656,8 +3725,10 @@ interactively, this is t."
(format " - Exit [%d]" exit-status)))))
(if (with-current-buffer buffer (> (point-max) (point-min)))
;; There's some output, display it
- (display-message-or-buffer buffer)
- ;; No output; error?
+ (progn
+ (display-message-or-buffer buffer)
+ (shell-command--set-point-after-cmd buffer))
+ ;; No output; error?
(let ((output
(if (and error-file
(< 0 (nth 7 (file-attributes error-file))))

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