bug#22452: 24.4; Tramp remote shell fails on remote+sudo+homedir destination

[Ken Manheimer]

I'm glad you're investigating, Michael!

Interesting that changing tramp-verbose avoids the problem. Sounds like that, in itself, might be a lead on the problem?

In any case, I do have a good workaround, which I'm sure you saw the reply, in the follow-up I sent just a moment ago to you and emacs-devel. For the sake of the bug transcript I'll repeat the substance of the message here:

I actually have a workaround, and the premise of it resides in the special conditions I included for the repeating the problem. In order to repeat the problem, you have to specifically use a default-directory that is set to the remote+sudo+homedir format, and not allow something like `(cd path)' to first resolve the home directory to an explicit path. So there's my workaround, for multishell - use `(cd path)', rather than directly setting default-directory.

Upshot is that I believe that there still is a bug worth unravelling [especially since it involves an aggravating and elusive "Selecting deleted buffer" event], in the way that shells start when default-directory is set to remote+sudo+homedir format, but I can avoid that by using `cd'.

Ken

On Sun, Jan 24, 2016 at 12:48 PM, Michael Albinus <michael.albinus@gmx.de> wrote:

Ken Manheimer <ken.manheimer@gmail.com> writes:

Hi Ken,

> Tramp fails to start a remote shell when the remote path is exactly of
> the form '/ssh:host|sudo:root@host:'. It fails with a message in the
> minibuffer, "Selecting deleted buffer".
>
> To reproduce the error:
>
> * Start emacs with -Q
> * In any buffer (*scratch* is fine):
> M-Esc (setq default-directory
> "/ssh:example.com|sudo:root@example.com:")
> * In that same buffer, Esc-x shell
>
> This fails (with "Selecting deleted buffer") for me in the version of
> emacs listed in the bug report and more recent versions, which I
> compiled, eg: GNU Emacs 24.5.50.1 (x86_64-apple-darwin14.5.0, NS
> apple-appkit-1348.17) of 2015-12-16 on twist.myriadicity.net.
>
> I can't get a backtrace for it, even if I set debug-on-error and
> signal-on-error.

Same here, hard to debug. The error doesn't happen if tramp-verbose is
less than 3 prior calling M-x shell. So maybe you bind it temporarily to
2 in your package, as workaround.

I'll continue to debug.

Best regards, Michael.