bug#36742: 25.2; shell-mode over TRAMP does not read remote history file as comint input ring

[Fan Yang <fan_yang@sjtu.edu.cn>]

* Bug description:

When using "M-x shell" on a remote file (say "/scp:yf@val17:"), a bash
is started at the server "val17" as the user "yf".  But the "*shell*"
buffer is started with an empty input ring.  It does not read bash
history file ("/scp:yf@val17:~/.bash_history") into comint input ring.

* What is expected:

When using "M-x shell" on a remote file (say "/scp:yf@val17:"), a bash
is started at the server "val17" as the user "yf".  The "*shell*"
1. has the content of "/scp:yf@val17:~/.bash_history" as comint input
   ring.  And I can use "M-p" to insert previous command, use "M-r" to
   isearch previous comamnd, etc.
2. the commands I have input in this "*shell*" will be appended to
   "/scp:yf@val17:~/.bash_history" after shell exit.
Just like what "shell-mode" does for local shell.

* To re-produce:

Here is the content of the dribble file of my re-producing this issue
(control characters are replaced with caret)

--8<---------------cut here---------------start------------->8---
^X^F/scp:yf@val17:
^[xshell

^[p^[p^[p^X^Cyes
--8<---------------cut here---------------end--------------->8---

* My findings, if I may:

The code of shell-mode shows

--8<---------------cut here---------------start------------->8---
      (setq comint-input-ring-file-name
	    (or (getenv "HISTFILE")
		(cond ((string-equal shell "bash") "~/.bash_history")
		      ((string-equal shell "ksh") "~/.sh_history")
		      (t "~/.history"))))
--8<---------------cut here---------------end--------------->8---

It seems remote file path is not considered.

* How big this issue is?

Have a shell history is convenient and saves a lot of typing repeated or
similar commands.  Me and many of my colleagues use shell history
isearch heavily.  It works very well for local shells.  It is a little
bit disappointing that it does not work on remote shells.

Best Regards,
Fan


In GNU Emacs 25.2.2 (x86_64-pc-linux-gnu, GTK+ Version 3.22.21)
 of 2017-09-23, modified by Debian built on lgw01-amd64-050
System Description:	Ubuntu 18.04.2 LTS

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
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 --with-sound=alsa --without-gconf --build x86_64-linux-gnu
 --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs25:/etc/emacs:/usr/local/share/emacs/25.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/25.2/site-lisp:/usr/share/emacs/site-lisp
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Configured features:
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ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11

Important settings:
  value of $LC_MONETARY: en_US.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: en_US.UTF-8
  value of $LANG: en_US.UTF-8
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Major mode: Lisp Interaction

Minor modes in effect:
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Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
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Memory information:
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