Re: .bashrc is sourced even for non-interactive shells (when run from sshd)

[Pierre Gaston]

On Sun, Jun 3, 2012 at 3:05 AM, Linda Walsh <bash@tlinx.org> wrote:
>
>
> Pierre Gaston wrote:
>
>> On Sat, Jun 2, 2012 at 8:24 PM, Mikel Ward <mikel@mikelward.com> wrote:
>>>
>>> On Sat, Jun 2, 2012 at 10:19 AM, Pierre Gaston <pierre.gaston@gmail.com>
>>> wrote:
>>>>
>>>> On Sat, Jun 2, 2012 at 8:15 PM, Mikel Ward <mikel@mikelward.com> wrote:
>>>>>
>>>>> bash sources .bashrc even for some non-interactive shells.
>>>
>>> ...
>>>>
>>>> "Remote non login non interactive shells"
>>>> Bash has a special compile time option that will cause it to source
>>>> the .bashrc file on non-login, non-interactive ssh sessions.
>>>
>>> IIUC, it was once a compile time option, but it's now hard-coded. �The
>>> isnetconn test doesn't seem to be toggled by any macro.
>>>
>>> � � �if ((run_by_ssh || isnetconn (fileno (stdin))) && shell_level < 2)
>>
>> but  run_by_ssh is:
>>
>> #ifdef SSH_SOURCE_BASHRC
>>      run_by_ssh = (find_variable ("SSH_CLIENT") != (SHELL_VAR *)0) ||
>>                   (find_variable ("SSH2_CLIENT") != (SHELL_VAR *)0);
>> #else
>>      run_by_ssh = 0;
>> #endif
>>
>
>
> I would say that's broken -- bash can detect if it is
> hooked up to a terminal for input, or not, but chooses not to.
>
> prelude:
>
> ans=("is "{not,}" a tty")
> alias sub=function
> sub echoAns { echo ${ans[$?==0]}; }
> alias }{=else {=then }=fi ?=if
>
> 4 basic cases...
>
> 1)
> Ishtar:...> if ssh  ishtar isatty 0 2>/dev/null; { echoAns; }{ echoAns; }
> .bashrc STDIN: is not a tty ( $-=hBc )
> is not a tty
>
>
> 2)
> Ishtar:...> if ssh -T ishtar isatty 0 2>/dev/null; { echoAns; }{ echoAns; }
> .bashrc STDIN: is not a tty ( $-=hBc )
> is not a tty
>
>
> 3)
> Ishtar:...> if ssh -tn ishtar isatty 0 2>/dev/null; { echoAns; }{ echoAns; }
> .bashrc STDIN: is not a tty ( $-=hBc )
> is not a tty
>
>
> 4)
> Ishtar:...> if ssh -t ishtar isatty 0 2>/dev/null; { echoAns; }{ echoAns; }
> .bashrc STDIN: is a tty ( $-=hBc )
> is a tty
>
> While it is arguable whether or not 1 & 2 are 'interactive' (they are but
> not in a character oriented way), #4, by:
>       --rcfile file
>              Execute commands from file instead of the standard personal
> ini-
>              tialization file ~/.bashrc if  the  shell  is  interactive
>  (see
>              INVOCATION below).
> -----------Under invocation:
>       An interactive shell is one started without  non-option  arguments
>  and
>       without the -c option whose standard input and error are both
> connected
>       to terminals .....
>
>  ***(as determined by isatty(3)),***
>
>       or one started with  the  -i
>       option.   PS1 is set and $- includes i if bash is interactive,
> allowing
>       a shell script or a startup file to test this state.
>
>
> By using the isatty test, none of 1-3 should be calling bashrc.
> You can note that the "-i" switch isn't specified at any point.
>
> Minimally I would claim #4 to be a bug, and from the manual, #1 and #2 are
> as
> well.  (-n redirects STDIN from /dev/null -- a definite "non-winner for
> interactivity).

In all your examples the shell will be called like: bash -c  'isatty 0
2'. If you use a bash compiled with the above option you can add 'ps
-p$$ -ocmd' at the top of your .bashrc to verify it.

They are all non-interactive because they are called with -c,
disregarding if they are connected to a terminal or not.