[PATCH] Add function eshell/clear to clear current eshell buffer

[PATCH] Add function eshell/clear to clear current eshell buffer

[vibhavp]

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Hello,
Eshell currently lacks a "clear" command. Since it cannot use the one
provided by the ncurses package, I added a patch which adds similar
functionality to eshell. It can be called by simply typing "clear" on
the eshell prompt.

Thanks


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[-- Attachment #2: eshell-clear patch --]
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diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 0b277c7..409ca23 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-08  Vibhav Pant  <vibhavp@gmail.com>
+
+	* eshell/esh-mode.el (eshell/clear): New function.
+
 2015-03-07  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* battery.el (battery-echo-area-format): Simplify default.
diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
index da83ec6..a1c71cc 100644
--- a/lisp/eshell/esh-mode.el
+++ b/lisp/eshell/esh-mode.el
@@ -902,6 +902,12 @@ When run interactively, widen the buffer first."
       (bury-buffer)
     (kill-buffer (current-buffer))))
 
+(defun eshell/clear ()
+  "Clear the eshell buffer."
+  (let ((inhibit-read-only t))
+    (erase-buffer)
+    (eshell-send-input)))
+
 (defun eshell-truncate-buffer ()
   "Truncate the buffer to `eshell-buffer-maximum-lines'.
 This function could be on `eshell-output-filter-functions' or bound to

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-- 
Vibhav Pant
vibhavp@gmail.com

Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[Vibhav Pant]

Also, since the patch is < 15 lines of code, I dont think a copyright
assignment should be required.

On Sun, Mar 8, 2015 at 10:52 AM,  <vibhavp@gmail.com> wrote:
> Hello,
> Eshell currently lacks a "clear" command. Since it cannot use the one
> provided by the ncurses package, I added a patch which adds similar
> functionality to eshell. It can be called by simply typing "clear" on
> the eshell prompt.
>
> Thanks
>
>
> --
> Vibhav Pant
> vibhavp@gmail.com
>



-- 
Vibhav Pant
vibhavp@gmail.com

Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[Bozhidar Batsov]

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Guess it should be bound to `C-c M-o` as the clear command for comint
buffers. On a related note - doesn't it make some sense for eshell do
derive from comint?

On 8 March 2015 at 07:23, Vibhav Pant <vibhavp@gmail.com> wrote:

> Also, since the patch is < 15 lines of code, I dont think a copyright
> assignment should be required.
>
> On Sun, Mar 8, 2015 at 10:52 AM,  <vibhavp@gmail.com> wrote:
> > Hello,
> > Eshell currently lacks a "clear" command. Since it cannot use the one
> > provided by the ncurses package, I added a patch which adds similar
> > functionality to eshell. It can be called by simply typing "clear" on
> > the eshell prompt.
> >
> > Thanks
> >
> >
> > --
> > Vibhav Pant
> > vibhavp@gmail.com
> >
>
>
>
> --
> Vibhav Pant
> vibhavp@gmail.com
>
>

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Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[vibhavp]

Bozhidar Batsov <bozhidar@batsov.com> writes:

> Guess it should be bound to `C-c M-o` as the clear command for comint
> buffers.

`C-c M-o` is bound to (eshell-mark-output), which does something similar
to clear, but instead of erasing the buffer, only moves the active
eshell prompt to the top of the window. However, once you enter a
newline at the prompt, the prompt goes back to its original position,
something which clear isn't supposed to do.

The documentation suggests that the command is used to narrow the buffer
to the region containing the last command's output.

-- 
Vibhav Pant
vibhavp@gmail.com

Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[Bozhidar Batsov]

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Yeah, this command seems pretty broken to me. Guess someone should have a
look at it.

On 8 March 2015 at 09:19, <vibhavp@gmail.com> wrote:

> Bozhidar Batsov <bozhidar@batsov.com> writes:
>
> > Guess it should be bound to `C-c M-o` as the clear command for comint
> > buffers.
>
> `C-c M-o` is bound to (eshell-mark-output), which does something similar
> to clear, but instead of erasing the buffer, only moves the active
> eshell prompt to the top of the window. However, once you enter a
> newline at the prompt, the prompt goes back to its original position,
> something which clear isn't supposed to do.
>
> The documentation suggests that the command is used to narrow the buffer
> to the region containing the last command's output.
>
> --
> Vibhav Pant
> vibhavp@gmail.com
>

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Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: vibhavp@gmail.com
> Date: Sun, 08 Mar 2015 10:52:10 +0530
> 
> Eshell currently lacks a "clear" command. Since it cannot use the one
> provided by the ncurses package, I added a patch which adds similar
> functionality to eshell. It can be called by simply typing "clear" on
> the eshell prompt.

Thanks.

As someone who was more than once in a situation where I would give
half of my kingdom for an opportunity to look again at the contents of
the screen I just "clear"ed, how about filling the window with blank
lines instead, so that the old contents are out of sight, but still
reachable?  Would that make sense?

Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[vibhavp]

Eli Zaretskii <eliz@gnu.org> writes:

> As someone who was more than once in a situation where I would give
> half of my kingdom for an opportunity to look again at the contents of
> the screen I just "clear"ed

Most shells do something list this, and moves the prompt the top of the
window. Elisp has something similar with (recenter-top-bottom), but
eshell overrides this by going to the window's bottom again.

> how about filling the window with blank
> lines instead, so that the old contents are out of sight, but still
> reachable?  Would that make sense?

Unfortunately, I don't know how to do that :(. Although, I think that
can be done with getting the number of lines between (point-max) and the
top of the window, and then inserting these many newlines.

-- 
Vibhav Pant
vibhavp@gmail.com

Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: vibhavp@gmail.com
> Cc: emacs-devel@gnu.org
> Date: Mon, 09 Mar 2015 00:58:12 +0530
> 
> > how about filling the window with blank
> > lines instead, so that the old contents are out of sight, but still
> > reachable?  Would that make sense?
> 
> Unfortunately, I don't know how to do that :(. Although, I think that
> can be done with getting the number of lines between (point-max) and the
> top of the window, and then inserting these many newlines.

Yes, exactly.  It shouldn't be hard.

Re: [PATCH] Add function eshell/clear to clear current eshell buffer

[vibhavp]

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Eli Zaretskii <eliz@gnu.org> writes:

> Yes, exactly.  It shouldn't be hard.

Done, does this look good?

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diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index b284ef1..3133cef 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-09  Vibhav Pant  <vibhavp@gmail.com>
+
+	* eshell/esh-mode.el (eshell/clear): New function.
+
 2015-03-09  Dmitry Gutov  <dgutov@yandex.ru>
 
 	* progmodes/ruby-mode.el (ruby-font-lock-keywords): Don't consider
diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
index da83ec6..41ee132 100644
--- a/lisp/eshell/esh-mode.el
+++ b/lisp/eshell/esh-mode.el
@@ -871,6 +871,13 @@ When run interactively, widen the buffer first."
   (goto-char (point-max))
   (recenter -1))
 
+(defun eshell/clear ()
+  "Clear the eshell-buffer"
+  (interactive)
+  (let ((number-newlines (count-lines (window-start) (point))))
+    (insert (make-string number-newlines ?\n)))
+    (eshell-send-input))
+
 (defun eshell-get-old-input (&optional use-current-region)
   "Return the command input on the current line."
   (if use-current-region

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Thanks
-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Gregor Zattler]

Hi Vibhav,
* vibhavp@gmail.com <vibhavp@gmail.com> [09. Mar. 2015]:
> +(defun eshell/clear ()
> +  "Clear the eshell-buffer"

Now this command does not clear the eshell buffer any more, but the
eshell window.  I think the doc string should say so because this has
security implications: The user may think some info is gone but actually
it’s only no longer visible.  How about:

"Scroll contents out of the eshell window by inserting newlines."

(let ((number-newlines (count-lines (window-start) (point))))
  (insert (make-string number-newlines ?\n)))
  (eshell-send-input))

> +  (interactive)
> +  (let ((number-newlines (count-lines (window-start) (point))))
> +    (insert (make-string number-newlines ?\n)))
> +    (eshell-send-input))

Doesn't this insert the newlines where ever the point is?
Shouldn't it append the newlines to the very end of the buffer
where ever point was before?

Ciao; Gregor

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

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Gregor Zattler <telegraph@gmx.net> writes:

> Now this command does not clear the eshell buffer any more, but the
> eshell window.  I think the doc string should say so because this has
> security implications: The user may think some info is gone but actually
> it’s only no longer visible.  How about:
>
> "Scroll contents out of the eshell window by inserting newlines."

Yep, attached patch.

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diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d8330a4..efb160c 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-09  Vibhav Pant <vibhavp@gmail.com>
+
+	* eshell/esh-mode.el (eshell/clear): New function.
+
 2015-03-09  Nicolas Petton <nicolas@petton.fr>
 
 	* emacs-lisp/seq.el (seq-into): New function.
diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
index da83ec6..41ee132 100644
--- a/lisp/eshell/esh-mode.el
+++ b/lisp/eshell/esh-mode.el
@@ -871,6 +871,13 @@ When run interactively, widen the buffer first."
   (goto-char (point-max))
   (recenter -1))
 
+(defun eshell/clear ()
+  "Clear the eshell-buffer"
+  (interactive)
+  (let ((number-newlines (count-lines (window-start) (point))))
+    (insert (make-string number-newlines ?\n)))
+    (eshell-send-input))
+
 (defun eshell-get-old-input (&optional use-current-region)
   "Return the command input on the current line."
   (if use-current-region

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> Doesn't this insert the newlines where ever the point is?
> Shouldn't it append the newlines to the very end of the buffer
> where ever point was before?

IIUC, Whenever the return key is pressed, (eshell-send-input)
automatically sets the point to end of the eshell buffer. So, the
newlines are always inserted at the buffer's end.

Thanks
-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

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> Yep, attached patch.

Oops, that wrong the wrong patch. Here's the correct one:

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diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d8330a4..efb160c 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-09  Vibhav Pant <vibhavp@gmail.com>
+
+	* eshell/esh-mode.el (eshell/clear): New function.
+
 2015-03-09  Nicolas Petton <nicolas@petton.fr>
 
 	* emacs-lisp/seq.el (seq-into): New function.
diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
index da83ec6..f134cb3 100644
--- a/lisp/eshell/esh-mode.el
+++ b/lisp/eshell/esh-mode.el
@@ -871,6 +871,13 @@ When run interactively, widen the buffer first."
   (goto-char (point-max))
   (recenter -1))
 
+(defun eshell/clear ()
+  "Scroll contents out of the eshell window by inserting newlines."
+  (interactive)
+  (let ((number-newlines (count-lines (window-start) (point))))
+    (insert (make-string number-newlines ?\n)))
+    (eshell-send-input))
+
 (defun eshell-get-old-input (&optional use-current-region)
   "Return the command input on the current line."
   (if use-current-region

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-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> Date: Mon, 9 Mar 2015 11:11:26 +0100
> From: Gregor Zattler <telegraph@gmx.net>
> 
> Hi Vibhav,
> * vibhavp@gmail.com <vibhavp@gmail.com> [09. Mar. 2015]:
> > +(defun eshell/clear ()
> > +  "Clear the eshell-buffer"
> 
> Now this command does not clear the eshell buffer any more, but the
> eshell window.  I think the doc string should say so because this has
> security implications: The user may think some info is gone but actually
> it’s only no longer visible.

The same happens with a few terminal emulators, so users should
already be expecting that possibility

> "Scroll contents out of the eshell window by inserting newlines."

The last part describes the implementation, which is not a good thing,
IMO.  So I suggest just

  Scroll contents of eshell window out of sight, leaving a blank window.

Thanks.

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

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Eli Zaretskii <eliz@gnu.org> writes:

>   Scroll contents of eshell window out of sight, leaving a blank window.

Here you go.

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[-- Attachment #2: eshell-clear.patch --]
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diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d8330a4..efb160c 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-09  Vibhav Pant <vibhavp@gmail.com>
+
+	* eshell/esh-mode.el (eshell/clear): New function.
+
 2015-03-09  Nicolas Petton <nicolas@petton.fr>
 
 	* emacs-lisp/seq.el (seq-into): New function.
diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
index da83ec6..15120cb 100644
--- a/lisp/eshell/esh-mode.el
+++ b/lisp/eshell/esh-mode.el
@@ -871,6 +871,13 @@ When run interactively, widen the buffer first."
   (goto-char (point-max))
   (recenter -1))
 
+(defun eshell/clear ()
+  "Scroll contents of eshell window out of sight, leaving a blank window."
+  (interactive)
+  (let ((number-newlines (count-lines (window-start) (point))))
+    (insert (make-string number-newlines ?\n)))
+    (eshell-send-input))
+
 (defun eshell-get-old-input (&optional use-current-region)
   "Return the command input on the current line."
   (if use-current-region

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-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: vibhavp@gmail.com
> Cc: Gregor Zattler <telegraph@gmx.net>,  emacs-devel@gnu.org
> Date: Mon, 09 Mar 2015 21:39:22 +0530
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >   Scroll contents of eshell window out of sight, leaving a blank window.
> 
> Here you go.

LGTM, thanks.

Re: Add function eshell/clear to clear current eshell buffer

[Vibhav Pant]

On Mon, Mar 9, 2015 at 10:13 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> LGTM, thanks.

Can the patch to master, or is there anything left to be worked upon?


-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Bozhidar Batsov]

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The name of the function is strange, btw. We don't use `/` is command names.

On 10 March 2015 at 05:27, Vibhav Pant <vibhavp@gmail.com> wrote:

> On Mon, Mar 9, 2015 at 10:13 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> > LGTM, thanks.
>
> Can the patch to master, or is there anything left to be worked upon?
>
>
> --
> Vibhav Pant
> vibhavp@gmail.com
>
>

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Re: Add function eshell/clear to clear current eshell buffer

[Ricardo Wurmus]

Bozhidar Batsov writes:

> The name of the function is strange, btw. We don't use `/` is command names.

The name is just right.  Any function with prefix "eshell/" becomes an
eshell command.  "eshell/clear" will be available on the eshell as
"clear".

Re: Add function eshell/clear to clear current eshell buffer

[Ted Zlatanov]

On Mon, 09 Mar 2015 17:59:34 +0200 Eli Zaretskii <eliz@gnu.org> wrote: 

>> Date: Mon, 9 Mar 2015 11:11:26 +0100
>> From: Gregor Zattler <telegraph@gmx.net>
>> 
>> Hi Vibhav,
>> * vibhavp@gmail.com <vibhavp@gmail.com> [09. Mar. 2015]:
>> > +(defun eshell/clear ()
>> > +  "Clear the eshell-buffer"
>> 
>> Now this command does not clear the eshell buffer any more, but the
>> eshell window.  I think the doc string should say so because this has
>> security implications: The user may think some info is gone but actually
>> it’s only no longer visible.

EZ> The same happens with a few terminal emulators, so users should
EZ> already be expecting that possibility

But eshell is not a terminal emulator.  It's a shell.  Emacs provides
the text UI around it.

I would rename `eshell/clear' to `eshell/clear-view' and also provide
`eshell/clear-buffer', if that's OK with Vibhav and everyone else?

Ted

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: Ted Zlatanov <tzz@lifelogs.com>
> Date: Sat, 18 Apr 2015 07:12:22 -0400
> 
> >> > +(defun eshell/clear ()
> >> > +  "Clear the eshell-buffer"
> >> 
> >> Now this command does not clear the eshell buffer any more, but the
> >> eshell window.  I think the doc string should say so because this has
> >> security implications: The user may think some info is gone but actually
> >> it’s only no longer visible.
> 
> EZ> The same happens with a few terminal emulators, so users should
> EZ> already be expecting that possibility
> 
> But eshell is not a terminal emulator.  It's a shell.  Emacs provides
> the text UI around it.

I don't see the significance of this observation for the issue at
hand.  Eshell is an implementation of a shell in Emacs Lisp, and as
such, Emacs is part of it.  Therefore, we should compare what Eshell's
command do with what shells+emulators do.

> I would rename `eshell/clear' to `eshell/clear-view' and also provide
> `eshell/clear-buffer', if that's OK with Vibhav and everyone else?

Eshell should have commands named like corresponding shell commands.
Having commands with no namesakes in popular shells makes very little
sense to me.

Re: Add function eshell/clear to clear current eshell buffer

[Ted Zlatanov]

On Sat, 18 Apr 2015 15:39:19 +0300 Eli Zaretskii <eliz@gnu.org> wrote: 

>> From: Ted Zlatanov <tzz@lifelogs.com>
>> Date: Sat, 18 Apr 2015 07:12:22 -0400
>> 
>> >> > +(defun eshell/clear ()
>> >> > +  "Clear the eshell-buffer"
>> >> 
>> >> Now this command does not clear the eshell buffer any more, but the
>> >> eshell window.  I think the doc string should say so because this has
>> >> security implications: The user may think some info is gone but actually
>> >> it’s only no longer visible.
>> 
EZ> The same happens with a few terminal emulators, so users should
EZ> already be expecting that possibility
>> 
>> But eshell is not a terminal emulator.  It's a shell.  Emacs provides
>> the text UI around it.

EZ> I don't see the significance of this observation for the issue at
EZ> hand.  Eshell is an implementation of a shell in Emacs Lisp, and as
EZ> such, Emacs is part of it.  Therefore, we should compare what Eshell's
EZ> command do with what shells+emulators do.

I think Emacs' concepts of windows and buffers should override the
typical terminal emulators' concepts of window and scrollback buffer.
Since Emacs typically doesn't clear just the window in normal usage,
it's strange to do it here (especially by inserting blank lines).

>> I would rename `eshell/clear' to `eshell/clear-view' and also provide
>> `eshell/clear-buffer', if that's OK with Vibhav and everyone else?

EZ> Eshell should have commands named like corresponding shell commands.
EZ> Having commands with no namesakes in popular shells makes very little
EZ> sense to me.

From the man page:

      clear clears your screen if this is possible, including its
      scrollback buffer (if the extended "E3" capability is defined).
      clear looks in the environment for the terminal type and then in
      the terminfo database to determine how to clear the screen.

So, unless we come up with some E3 equivalent, I think it should be two
commands or in some other way apparent that there's two operation modes
to the `clear' eshell command.

For simplicity, how about `eshell/clear' for the window and
`eshell/clear-scrollback' for the whole buffer (also invoked with
universal-prefix on `eshell/clear')? The scrollback clear should IMO
also make sure undo is enabled, but the text is not in any registers.

Ted

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: Ted Zlatanov <tzz@lifelogs.com>
> Date: Sat, 18 Apr 2015 09:31:35 -0400
> 
> >> But eshell is not a terminal emulator.  It's a shell.  Emacs provides
> >> the text UI around it.
> 
> EZ> I don't see the significance of this observation for the issue at
> EZ> hand.  Eshell is an implementation of a shell in Emacs Lisp, and as
> EZ> such, Emacs is part of it.  Therefore, we should compare what Eshell's
> EZ> command do with what shells+emulators do.
> 
> I think Emacs' concepts of windows and buffers should override the
> typical terminal emulators' concepts of window and scrollback buffer.

Not when we are talking about a shell.

> Since Emacs typically doesn't clear just the window in normal usage,
> it's strange to do it here (especially by inserting blank lines).

It's a command; if you don't like it, don't use it.

But people who do want to start with a "clean slate" should be able
to.

> >> I would rename `eshell/clear' to `eshell/clear-view' and also provide
> >> `eshell/clear-buffer', if that's OK with Vibhav and everyone else?
> 
> EZ> Eshell should have commands named like corresponding shell commands.
> EZ> Having commands with no namesakes in popular shells makes very little
> EZ> sense to me.
> 
> >From the man page:
> 
>       clear clears your screen if this is possible, including its
>       scrollback buffer (if the extended "E3" capability is defined).
>       clear looks in the environment for the terminal type and then in
>       the terminfo database to determine how to clear the screen.
> 
> So, unless we come up with some E3 equivalent, I think it should be two
> commands or in some other way apparent that there's two operation modes
> to the `clear' eshell command.

The idea was that cleaning the scrollback buffer make little sense in
Emacs, because you gain nothing, but lose a chance to change your mind
later.  So I think inventing the equivalent of E3 would be wasted
effort.

> For simplicity, how about `eshell/clear' for the window and
> `eshell/clear-scrollback' for the whole buffer (also invoked with
> universal-prefix on `eshell/clear')? The scrollback clear should IMO
> also make sure undo is enabled, but the text is not in any registers.

I'm not necessarily object, but again: what would be the purpose of
removing the scrollback? what will that give you?

Re: Add function eshell/clear to clear current eshell buffer

[Ted Zlatanov]

On Sat, 18 Apr 2015 16:43:16 +0300 Eli Zaretskii <eliz@gnu.org> wrote: 

>> For simplicity, how about `eshell/clear' for the window and
>> `eshell/clear-scrollback' for the whole buffer (also invoked with
>> universal-prefix on `eshell/clear')? The scrollback clear should IMO
>> also make sure undo is enabled, but the text is not in any registers.

EZ> I'm not necessarily object, but again: what would be the purpose of
EZ> removing the scrollback? what will that give you?

Often I force-close an eshell buffer because I don't want the
interaction to remain in memory, because some password was echoed (to
the terminal, in a URL, etc.).

Perhaps it's not a common need so triggering a full scrollback clear
with the universal prefix is probably the best way forward.

Ted

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

Eli Zaretskii <eliz@gnu.org> writes:

>  So I think inventing the equivalent of E3 would be wasted
> effort.

It shouldn't be really that hard, my earlier patch removed the
scrollback, and we call always add another command to do that. I have no
problem with writing a patch for the latter.

> I'm not necessarily object, but again: what would be the purpose of
> removing the scrollback? what will that give you?

Privacy? The scrollback might have some sensitive info, so someone might
want it cleared.

-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: vibhavp@gmail.com
> Cc: emacs-devel@gnu.org
> Date: Sat, 18 Apr 2015 20:48:42 +0530
> 
> > I'm not necessarily object, but again: what would be the purpose of
> > removing the scrollback? what will that give you?
> 
> Privacy? The scrollback might have some sensitive info, so someone might
> want it cleared.

There could be no privacy if the attackers have physical access to
your computer.

But, as I said, I don't object.

Re: Add function eshell/clear to clear current eshell buffer

[chad]

> On 18 Apr 2015, at 08:23, Eli Zaretskii <eliz@gnu.org> wrote:
>>> I'm not necessarily object, but again: what would be the purpose of
>>> removing the scrollback? what will that give you?
>> 
>> Privacy? The scrollback might have some sensitive info, so someone might
>> want it cleared.
> 
> There could be no privacy if the attackers have physical access to
> your computer.

This conflates privacy with security. If I want to pass my computer
to someone else (a common practice in pair programming, to pick one
example), but I want to clear out some sensitive info first, it
shouldnt be hard to do. Making the emacs shell interface work like
a non-emacs shell interface seems like a perfectly reasonable thing
to do (especially since eshell already lets you hide the previous
context simply by hitting C-l C-l).

~Chad

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: chad <yandros@gmail.com>
> Date: Sat, 18 Apr 2015 12:10:23 -0700
> 
> > There could be no privacy if the attackers have physical access to
> > your computer.
> 
> This conflates privacy with security.

No, it doesn't.

> If I want to pass my computer to someone else (a common practice in
> pair programming, to pick one example), but I want to clear out some
> sensitive info first, it shouldnt be hard to do.

Good luck keeping your privacy that way!

> Making the emacs shell interface work like a non-emacs shell
> interface seems like a perfectly reasonable thing to do

We are in violent agreement.

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

[-- Attachment #1: Type: text/plain, Size: 150 bytes --]

Attached a patch which adds a clear-scrollback command to eshell. If it
looks good, I'll push the patch to master with the relevant info in
etc/NEWS.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: esh-clear-scrollback.patch --]
[-- Type: text/x-diff, Size: 603 bytes --]

diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
index 15120cb..21026b2 100644
--- a/lisp/eshell/esh-mode.el
+++ b/lisp/eshell/esh-mode.el
@@ -878,6 +878,12 @@ When run interactively, widen the buffer first."
     (insert (make-string number-newlines ?\n)))
     (eshell-send-input))
 
+(defun eshell/clear-scrollback ()
+    "Clear the scrollback content of the eshell window."
+  (interactive)
+  (let ((inhibit-read-only t))
+    (erase-buffer)))
+
 (defun eshell-get-old-input (&optional use-current-region)
   "Return the command input on the current line."
   (if use-current-region

[-- Attachment #3: Type: text/plain, Size: 35 bytes --]


-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Ted Zlatanov]

On Sun, 19 Apr 2015 01:43:49 +0530 vibhavp@gmail.com wrote: 

v> Attached a patch which adds a clear-scrollback command to eshell. If it
v> looks good, I'll push the patch to master with the relevant info in
v> etc/NEWS.

v> diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
v> index 15120cb..21026b2 100644
v> --- a/lisp/eshell/esh-mode.el
v> +++ b/lisp/eshell/esh-mode.el
v> @@ -878,6 +878,12 @@ When run interactively, widen the buffer first."
v>      (insert (make-string number-newlines ?\n)))
v>      (eshell-send-input))
 
v> +(defun eshell/clear-scrollback ()
v> +    "Clear the scrollback content of the eshell window."
v> +  (interactive)
v> +  (let ((inhibit-read-only t))
v> +    (erase-buffer)))
v> +
v>  (defun eshell-get-old-input (&optional use-current-region)
v>    "Return the command input on the current line."
v>    (if use-current-region

That looks great.  Could you also make it available through
`C-u M-x eshell/clear'?  Or maybe "clear t" at the prompt?  Whatever you
think is best.

Ted

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

[-- Attachment #1: Type: text/plain, Size: 146 bytes --]

Ted Zlatanov <tzz@lifelogs.com> writes:

> That looks great.  Could you also make it available through
> `C-u M-x eshell/clear'?

Attached Patch.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: esh-clear-scrollback.patch --]
[-- Type: text/x-diff, Size: 1508 bytes --]

diff --git a/etc/NEWS b/etc/NEWS
index 5e312ed..5bb84e1 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -610,6 +610,7 @@ command line's password prompt.
 ** Eshell
 
 *** The new built-in command `clear' can scroll window contents out of sight.
+If provided with an optional non-nil argument, the scrollback contents will be cleared.
 
 ** Browse-url
 
diff --git a/lisp/eshell/esh-mode.el b/lisp/eshell/esh-mode.el
index 15120cb..54e52b9 100644
--- a/lisp/eshell/esh-mode.el
+++ b/lisp/eshell/esh-mode.el
@@ -871,12 +871,20 @@ When run interactively, widen the buffer first."
   (goto-char (point-max))
   (recenter -1))
 
-(defun eshell/clear ()
-  "Scroll contents of eshell window out of sight, leaving a blank window."
+(defun eshell/clear (&optional scrollback)
+  "Scroll contents of eshell window out of sight, leaving a blank window.
+If SCROLLBACK is non-nil, clear the scollback contents."
   (interactive)
-  (let ((number-newlines (count-lines (window-start) (point))))
-    (insert (make-string number-newlines ?\n)))
-    (eshell-send-input))
+  (if scrollback
+      (eshell/clear-scrollback)
+    (let ((number-newlines (count-lines (window-start) (point))))
+      (insert (make-string number-newlines ?\n))
+      (eshell-send-input))))
+
+(defun eshell/clear-scrollback ()
+  "Clear the scrollback content of the eshell window."
+  (let ((inhibit-read-only t))
+    (erase-buffer)))
 
 (defun eshell-get-old-input (&optional use-current-region)
   "Return the command input on the current line."

[-- Attachment #3: Type: text/plain, Size: 35 bytes --]


-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: vibhavp@gmail.com
> Date: Sun, 19 Apr 2015 09:56:45 +0530
> 
> Ted Zlatanov <tzz@lifelogs.com> writes:
> 
> > That looks great.  Could you also make it available through
> > `C-u M-x eshell/clear'?
> 
> Attached Patch.

Looks good to me, thanks.  Bonus points for updating eshell.texi as
well.

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

Eli Zaretskii <eliz@gnu.org> writes:

> Looks good to me, thanks.  Bonus points for updating eshell.texi as
> well.

I've pushed the changes, which include an entry for "clear" in
eshell.texi

Thanks.
-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: vibhavp@gmail.com
> Date: Sun, 19 Apr 2015 23:36:31 +0530
> Cc: emacs-devel@gnu.org
> 
> I've pushed the changes, which include an entry for "clear" in
> eshell.texi

Thanks.  That means you should mark the NEWS entry with "+++", as
explained in the beginning of that file.

Re: Add function eshell/clear to clear current eshell buffer

[vibhavp]

Eli Zaretskii <eliz@gnu.org> writes:

> Thanks.  That means you should mark the NEWS entry with "+++", as
> explained in the beginning of that file.

Done, sorry for forgetting that.

-- 
Vibhav Pant
vibhavp@gmail.com

Re: Add function eshell/clear to clear current eshell buffer

[Eli Zaretskii]

> From: vibhavp@gmail.com
> Date: Mon, 20 Apr 2015 00:19:20 +0530
> Cc: emacs-devel@gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Thanks.  That means you should mark the NEWS entry with "+++", as
> > explained in the beginning of that file.
> 
> Done, sorry for forgetting that.

No sweat, thanks for working on this.

Re: Add function eshell/clear to clear current eshell buffer

[Ted Zlatanov]

On Sun, 19 Apr 2015 21:53:29 +0300 Eli Zaretskii <eliz@gnu.org> wrote: 

>> From: vibhavp@gmail.com
>> Date: Mon, 20 Apr 2015 00:19:20 +0530
>> Cc: emacs-devel@gnu.org
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> > Thanks.  That means you should mark the NEWS entry with "+++", as
>> > explained in the beginning of that file.
>> 
>> Done, sorry for forgetting that.

EZ> No sweat, thanks for working on this.

I really appreciate it too, Vibhav!

Ted