Re: bash source code block: problem after ssh commands

[Bruno Barbier <brubar.cs@gmail.com>]

Hi Matt, Ihor, Alain,

Ihor Radchenko <yantar92@posteo.net> writes:

> Alain.Cochard@unistra.fr writes:
>
>> At the most basic user level (i.e., non lisp aware), why is it not
>> necessarily a bug if "something" does the expected in an X terminal
>> but not in an emacs terminal?  I think Matt and I (and others) are on
>> the same page here, and he already essentially drafted the bug report
>> I would have sent (only better).
>
> WRT M-x shell, feel free to submit a bug report. I mostly pointed that
> the problem with M-x shell is not the problem you originally ran to. It
> is a different problem (also, we ran into it in the past).

FWIW, M-x shell differs from what a plain terminal is doing (xterm, in
my case), but, I do prefer 'M-x shell' behavior: it allows me to copy
multiple lines, getting the same results as when I type them manually,
or copy them line by line. My xterm doesn't seem to allow me to do that.


>> What also confuses me is that it seems to me that, in the minimum
>> working example, you consider the ssh command and the read command as
>> equivalent.  But I don't even enter the password when using ssh...

I've introduced the 'read' example, as a simpler way to modify the
standard input and get the same kind of "unexpected" results, without
relying on SSH.  It seems that I have only caused confusion, sorry about
that.

IIUC, the OP example is not working because SSH is modifying the
standard input (with or without passwords).

> I was only able to reproduce your problem with ssh asking a password.
> We are discussing the reproduced case.
>
> If you see problems with
>    #+begin_src bash :results output
>    ssh cochard@fruc.u-strasbg.fr "echo foo>foo_file"
>    echo "bar"
>    #+end_src
>
> even when ssh does not ask for a password, please provide more detailed
> reproducer that we can replicate locally without guessing your ssh config.
>

I'm not the OP, but, my SSH is configured to work without passwords and
SSH is still consuming lines from standard input:

    #+begin_src bash :results output
    ssh phone echo "remote"
    echo "local"
    #+end_src

    #+RESULTS:
    : remote

It looks like it is a known SSH "feature" (see
https://unix.stackexchange.com/a/688024):

    #+begin_src bash :results output
    seq 1000000 | (ssh phone sleep 1; wc -l)
    #+end_src

    #+RESULTS:
    : 675173

Same block, but asking SSH to not use stdin (using '-n' as mentionned in
this thread):

    #+begin_src bash :results output
    seq 1000000 | (ssh -n phone sleep 1; wc -l)
    #+end_src

    #+RESULTS:
    : 1000000

IMHO, what ob-shell is doing today seems a valid way of evaluating
source blocks (and it seems to have been like that for a long time).  It
should probably be documented somewhere, so that users know how to write
their source blocks, or switch to another way, like adding a :cmdline
parameter as mentionned in this thread.


Hoping I didn't increase the confusion again,
:-)


Bruno




> -- 
> Ihor Radchenko // yantar92,
> Org mode contributor,
> Learn more about Org mode at <https://orgmode.org/>.
> Support Org development at <https://liberapay.com/org-mode>,
> or support my work at <https://liberapay.com/yantar92>