Re: Unwanted `^A' and `^B' characters in bash prompt.

[Lute Kamstra]

Richard Stallman <address@hidden> writes:

>     This, however, does not solve the problem for users of current
>     versions of bash (including me :-( ).  So I wrote a small
>     function that removes the unwanted `^A' and `^B' characters from
>     the bash prompt.  Shall I put this function in etc/PROBLEMS as
>     shown in the patch below?
>
> Is there a reasonable way to install this code in comint.el or
> shell.el that won't do any harm to users in other situations?  All
> else being equal, it would be better to DTRT automatically than to
> make the user go to an effort to compensate.

The patch below should do the job.

I'll commit it in a few days if nobody objects.


  Lute.



*** lisp/shell.el.~1.118.~      2003-01-31 16:18:17.000000000 +0100
--- lisp/shell.el       2003-06-02 16:12:32.000000000 +0200
***************
*** 454,462 ****
        (setq shell-dirstack-query
            (cond ((string-equal shell "sh") "pwd")
                  ((string-equal shell "ksh") "echo $PWD ~-")
!                 (t "dirs"))))
      (comint-read-input-ring t)))
  
  (defun shell-write-history-on-exit (process event)
    "Called when the shell process is stopped.
  
--- 454,483 ----
        (setq shell-dirstack-query
            (cond ((string-equal shell "sh") "pwd")
                  ((string-equal shell "ksh") "echo $PWD ~-")
!                 (t "dirs")))
!       ;; Bypass a bug in certain versions of bash.
!       (when (string-equal shell "bash")
!         (add-hook 'comint-output-filter-functions
!                   'shell-filter-ctrl-a-ctrl-b nil t)))
      (comint-read-input-ring t)))
  
+ (defun shell-filter-ctrl-a-ctrl-b (string)
+   "Remove `^A' and `^B' characters from comint output.
+ 
+ Bash uses these characters as internal quoting characters in its
+ prompt.  Due to a bug in some bash versions (including 2.03,
+ 2.04, and 2.05b), they may erroneously show up when Select
+ Graphic Rendition (SGR) control sequences (formerly known as ANSI
+ escape sequences) are used to color the prompt.
+ 
+ This function can be put on `comint-output-filter-functions'.
+ The argument STRING is ignored."
+   (let ((pmark (process-mark (get-buffer-process (current-buffer)))))
+     (save-excursion
+       (goto-char (or comint-last-output-start (point-min)))
+       (while (re-search-forward "[\C-a\C-b]" pmark t)
+         (replace-match "")))))
+ 
  (defun shell-write-history-on-exit (process event)
    "Called when the shell process is stopped.