bug#27612: 25.2; invoking term from a remote eshell uses the local path

bug#27612: 25.2; invoking term from a remote eshell uses the local path

[Pablo Barbachano]

M-x eshell
$ cd /ssh:remote-host:
$ hostname
<remote-hostname>

$ term hostname
<local-hostname>

term does not seem to get the default-directory from eshell.

There's a similar unanswered question in emacs stackexchange: https://emacs.stackexchange.com/questions/17862/eshell-visual-commands-with-tramp



In GNU Emacs 25.2.1 (x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2017-07-01, modified by Debian built on trouble
Windowing system distributor 'The X.Org Foundation', version 11.0.11902000
System Description:	Debian GNU/Linux testing (buster)

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
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 --localstatedir=/var/lib --infodir=/usr/share/info
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Configured features:
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LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS LUCID X11

Important settings:
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  locale-coding-system: utf-8-unix

Major mode: EShell

Minor modes in effect:
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Load-path shadows:
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bug#27612: 25.2; invoking term from a remote eshell uses the local path

[Michael Albinus]

Pablo Barbachano <pablo.barbachano@gmail.com> writes:

Hi Pablo,

> M-x eshell
> $ cd /ssh:remote-host:
> $ hostname
> <remote-hostname>
>
> $ term hostname
> <local-hostname>
>
> term does not seem to get the default-directory from eshell.

That is because term.el is not Tramp-aware. In `term-exec-1', it uses
`start-process' instead of `start-file-process'.

One could replace this, but scanning term.el, there seems to be a tight
integration with ange-ftp. So I guess it needs further work to cooperate
with Tramp.

I'm not a term.el user, so I don't know, whether it is a feature to run
always locally. Other people might tell, whether it would be appropriate
to support remoteness.

If yes, I could try to migrate term.el. But this would take time anyway,
understanding 4500 lines of unknown code. And maybe it is not possible
at all to support a full equipped remote terminal in Emacs.

Best regards, Michael.

bug#27612: 25.2; invoking term from a remote eshell uses the local path

[Pablo Barbachano]

Hi Michael,

Michael Albinus <michael.albinus@gmx.de> writes:

> That is because term.el is not Tramp-aware. In `term-exec-1', it uses
> `start-process' instead of `start-file-process'.

I tried that and my dummy test case suddenly worked. So that's enough to make it work, but more complex programs like 'top' or 'ipython' seem to have the output mangled. For example if I now do `term bash`

```
$ echo -e "1"
             1
              $ echo -e "\r1"
1
```

So something is going on with how the newlines are interpreted in the terminal. This does not happen if I run them locally.

I can try playing with this for some time and maybe send a patch.

Thanks for the pointer!
--
Pablo

bug#27612: 25.2; invoking term from a remote eshell uses the local path

[Michael Albinus]

Pablo Barbachano <pablo.barbachano@gmail.com> writes:

> Hi Michael,

Hi Pablo,

>> That is because term.el is not Tramp-aware. In `term-exec-1', it uses
>> `start-process' instead of `start-file-process'.
>
> I tried that and my dummy test case suddenly worked.

Sure. "hostnme" just dumps a string, and it doesn't send escape
sequences to the terminal.

> So that's enough to make it work, but more complex programs like 'top' or 'ipython' seem to have the output mangled. For example if I now do `term bash`
>
> ```
> $ echo -e "1"
>              1
>               $ echo -e "\r1"
> 1
> ```
>
> So something is going on with how the newlines are interpreted in the terminal. This does not happen if I run them locally.
>
> I can try playing with this for some time and maybe send a patch.

You might try it. But I believe it is more than just newline
handling. Escape sequences are sent, and the buffer playing the tty is
not prepared for this in the remote case. I would start with the
process-filter.

> Thanks for the pointer!
> --
> Pablo

Best regards, Michael.