bug#71554: 29.3; eshell-command async buffer behavior

[Thierry Volpiatto <thievol@posteo.net>]

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Thierry Volpiatto <thievol@posteo.net> writes:

> Jim Porter <jporterbugs@gmail.com> writes:
>
>> On 6/14/2024 1:32 PM, Thierry Volpiatto wrote:
>>> Because IMO what shell-command is doing is annoying, no need to duplicate
>>> this annoyance, after all when running such a command in a terminal
>>> already running a detached process, nothing is asked, so why doing this
>>> in emacs?
>>> Or at least make it optional?
>>
>> 'shell-command' has several possible options for this behavior. See
>> 'async-shell-command-buffer'.
>
> Ah, didn't know this one, thanks.
> What about something like this reusing async-shell-command-buffer (not
> fully tested)?
>
> diff --git a/lisp/eshell/eshell.el b/lisp/eshell/eshell.el
> index 18e05a371a4..774f25d71b0 100644
> --- a/lisp/eshell/eshell.el
> +++ b/lisp/eshell/eshell.el
> @@ -302,13 +302,25 @@ argument), then insert output into the current buffer at point."
>  		       ,(eshell-parse-command command))
>                      command))
>  	     intr
> +             unique
>  	     (bufname (if (eq (car-safe proc) :eshell-background)
>  			  "*Eshell Async Command Output*"
>  			(setq intr t)
>  			"*Eshell Command Output*")))
> -	(if (buffer-live-p (get-buffer bufname))
> -	    (kill-buffer bufname))
> -	(rename-buffer bufname)
> +	(when (buffer-live-p (get-buffer bufname))
> +          (pcase async-shell-command-buffer
> +            ('confirm-kill-process
> +             (shell-command--same-buffer-confirm "Kill it")
> +             (kill-buffer bufname))
> +	    ('confirm-new-buffer
> +             (shell-command--same-buffer-confirm "Use a new buffer")
> +             (setq unique t))
> +            ('new-buffer (setq unique t))
> +            ('confirm-rename-buffer
> +             (shell-command--same-buffer-confirm "Rename it")
> +             (kill-buffer bufname))
> +            ('rename-buffer (kill-buffer bufname))))
> +	(rename-buffer bufname unique)
>  	;; things get a little coarse here, since the desire is to
>  	;; make the output as attractive as possible, with no
>  	;; extraneous newlines

This patch doesn't work if user kill for some reason the initial process
buffer, we have to check if other buffers are alive.  Also having a new
variable eshell-command-async-buffer instead of reusing
async-shell-command-buffer is better IMO.
Here a patch that fix these issues.

-- 
Thierry

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From 4d9d7b3ce5a5370b733ceac9ebebf40987113810 Mon Sep 17 00:00:00 2001
From: Thierry Volpiatto <thievol@posteo.net>
Date: Wed, 19 Jun 2024 12:02:59 +0200
Subject: [PATCH] Use async-shell-command-buffer in eshell-command fix
 bug#71554

* lisp/eshell/eshell.el (eshell-command): Allow using multiple buffers.
(eshell-command-async-buffer): New user var.
---
 lisp/eshell/eshell.el | 66 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 60 insertions(+), 6 deletions(-)

diff --git a/lisp/eshell/eshell.el b/lisp/eshell/eshell.el
index 18e05a371a4..c84b450956a 100644
--- a/lisp/eshell/eshell.el
+++ b/lisp/eshell/eshell.el
@@ -216,6 +216,34 @@ named \"*eshell*<2>\"."
   :type 'string
   :group 'eshell)
 
+(defcustom eshell-command-async-buffer 'new-buffer
+  "What to do when the output buffer is used by another shell command.
+This option specifies how to resolve the conflict where a new command
+wants to direct its output to the buffer whose name is stored
+in `eshell-command-buffer-name-async', but that buffer is already
+taken by another running shell command.
+
+The value `confirm-kill-process' is used to ask for confirmation before
+killing the already running process and running a new process
+in the same buffer, `confirm-new-buffer' for confirmation before running
+the command in a new buffer with a name other than the default buffer name,
+`new-buffer' for doing the same without confirmation,
+`confirm-rename-buffer' for confirmation before renaming the existing
+output buffer and running a new command in the default buffer,
+`rename-buffer' for doing the same without confirmation."
+  :type '(choice (const :tag "Confirm killing of running command"
+			confirm-kill-process)
+		 (const :tag "Confirm creation of a new buffer"
+			confirm-new-buffer)
+		 (const :tag "Create a new buffer"
+			new-buffer)
+		 (const :tag "Confirm renaming of existing buffer"
+			confirm-rename-buffer)
+		 (const :tag "Rename the existing buffer"
+			rename-buffer))
+  :group 'shell
+  :version "30.1")
+
 ;;;_* Running Eshell
 ;;
 ;; There are only three commands used to invoke Eshell.  The first two
@@ -283,11 +311,18 @@ information on Eshell, see Info node `(eshell)Top'."
                                   (eshell-command-mode +1))
       (read-from-minibuffer prompt))))
 
+(defvar eshell-command-buffer-name-async "*Eshell Async Command Output*")
+(defvar eshell-command-buffer-name-sync "*Eshell Command Output*")
 ;;;###autoload
 (defun eshell-command (command &optional to-current-buffer)
   "Execute the Eshell command string COMMAND.
 If TO-CURRENT-BUFFER is non-nil (interactively, with the prefix
-argument), then insert output into the current buffer at point."
+argument), then insert output into the current buffer at point.
+
+When \"&\" is added at end of command, the command is async and its output
+appears in a specific buffer.  You can customize
+`eshell-command-async-buffer' to specify what to do when this output
+buffer is already taken by another running shell command."
   (interactive (list (eshell-read-command)
                      current-prefix-arg))
   (save-excursion
@@ -302,13 +337,32 @@ argument), then insert output into the current buffer at point."
 		       ,(eshell-parse-command command))
                     command))
 	     intr
+             unique
 	     (bufname (if (eq (car-safe proc) :eshell-background)
-			  "*Eshell Async Command Output*"
+			  eshell-command-buffer-name-async
 			(setq intr t)
-			"*Eshell Command Output*")))
-	(if (buffer-live-p (get-buffer bufname))
-	    (kill-buffer bufname))
-	(rename-buffer bufname)
+			eshell-command-buffer-name-sync)))
+	(when (or (buffer-live-p (get-buffer bufname))
+                  (cl-loop for buf in (buffer-list)
+                           thereis (and (string-match-p
+                                         (regexp-quote
+                                          (substring
+                                           bufname 0 (1- (length bufname))))
+                                         (buffer-name buf))
+                                        (buffer-live-p buf))))
+          (pcase eshell-command-async-buffer
+            ('confirm-kill-process
+             (shell-command--same-buffer-confirm "Kill it")
+             (kill-buffer bufname))
+	    ('confirm-new-buffer
+             (shell-command--same-buffer-confirm "Use a new buffer")
+             (setq unique t))
+            ('new-buffer (setq unique t))
+            ('confirm-rename-buffer
+             (shell-command--same-buffer-confirm "Rename it")
+             (kill-buffer bufname))
+            ('rename-buffer (kill-buffer bufname))))
+	(rename-buffer bufname unique)
 	;; things get a little coarse here, since the desire is to
 	;; make the output as attractive as possible, with no
 	;; extraneous newlines
-- 
2.34.1


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