bug#20380: 24.5; (shell-command-on-region ... "*Messages*") yields "Buffer is read-only" error

bug#20380: 24.5; (shell-command-on-region ... "*Messages*") yields "Buffer is read-only" error

[Vincent Lefevre]

I have the following problem with Emacs 24:

emacs -Q --eval \
  '(shell-command-on-region (point) (point) "cp" t t "*Messages*")' tst.txt

yields a "Buffer is read-only: #<buffer *Messages*>" error instead of
outputting the standard error from "cp" to the buffer *Messages* like
with Emacs 23.


In GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.5)
 of 2015-04-20 on ypig
Windowing system distributor `The X.Org Foundation', version 11.0.11604000
System Description:	Debian GNU/Linux 8.0 (jessie)

Configured using:
 `configure --prefix=/usr/local/emacs-24.5'

Important settings:
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: en_US.UTF-8
  value of $LC_TIME: en_DK
  value of $LANG: POSIX
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  display-time-mode: t
  show-paren-mode: t
  tooltip-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Loading /home/vlefevre/share/emacs/site-lisp/mutteditor.el (source)...done
Loading time...done
For information about GNU Emacs and the GNU system, type C-h C-a.
eval: Buffer is read-only: #<buffer *Messages*>
Quit

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr warnings emacsbug message format-spec
rfc822 mml easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util help-fns mail-prsvr mail-utils time cus-start
cus-load paren cc-styles cc-align cc-engine cc-vars cc-defs edmacro
kmacro cl-loaddefs cl-lib time-date tooltip electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list newcomment lisp-mode prog-mode register
page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core frame cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew
greek romanian slovak czech european ethiopic indian cyrillic chinese
case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
gfilenotify dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty emacs)

Memory information:
((conses 16 91573 8381)
 (symbols 48 20235 0)
 (miscs 40 100 93)
 (strings 32 14697 4833)
 (string-bytes 1 463225)
 (vectors 16 10255)
 (vector-slots 8 395374 4317)
 (floats 8 70 262)
 (intervals 56 187 0)
 (buffers 960 12)
 (heap 1024 34252 817))

bug#20380: 24.5; (shell-command-on-region ... "*Messages*") yields "Buffer is read-only" error

[Alexis]

Vincent Lefevre <vincent@vinc17.net> writes:

> I have the following problem with Emacs 24:
>
> emacs -Q --eval \ 
>   '(shell-command-on-region (point) (point) "cp" t t 
>   "*Messages*")' tst.txt
>
> yields a "Buffer is read-only: #<buffer *Messages*>" error 
> instead of outputting the standard error from "cp" to the buffer 
> *Messages* like with Emacs 23.

NEWS section "Changes in Emacs 24.4" states: 
 
    ** The *Messages* buffer is created in `messages-buffer-mode', 
    a new major mode, with read-only status.


Alexis.

bug#20380: 24.5; (shell-command-on-region ... "*Messages*") yields "Buffer is read-only" error

[Eli Zaretskii]

> From: Alexis <flexibeast@gmail.com>
> Date: Mon, 20 Apr 2015 19:51:57 +1000
> 
> 
> Vincent Lefevre <vincent@vinc17.net> writes:
> 
> > I have the following problem with Emacs 24:
> >
> > emacs -Q --eval \ 
> >   '(shell-command-on-region (point) (point) "cp" t t 
> >   "*Messages*")' tst.txt
> >
> > yields a "Buffer is read-only: #<buffer *Messages*>" error 
> > instead of outputting the standard error from "cp" to the buffer 
> > *Messages* like with Emacs 23.
> 
> NEWS section "Changes in Emacs 24.4" states: 
>  
>     ** The *Messages* buffer is created in `messages-buffer-mode', 
>     a new major mode, with read-only status.

Indeed, this is a new feature.  If you want to know why it was
introduced, read this discussion:

  http://lists.gnu.org/archive/html/emacs-devel/2010-02/msg00135.html