On Mon, Nov 2, 2009 at 11:18 AM, ladislav klenovic <[email protected]> wrote:
> 2009/11/1 Denys Vlasenko <[email protected]>
>>
>> On Thursday 29 October 2009 15:55, ladislav klenovic wrote:
>> > As Detlef said I don't know have to specify that in inittab thus I run
>> > the
>> > shell regardless whether there is or not a debug console.
>> > I choose the tty0 according to busybox 1.2.2 which works fine for me. So
>> > maybe some kind of configuration option which could
>> > specify which device to use if no console is available would make sense.
>>
>> I don't like this. A configuration option is not flehible. It would be a
>> hack.
>
> What is hackish on it if I know that the shell can run on e.g. tty0 if the
> debug console is missing?

It's a hack because it makes an arbitrary device, /dev/tty0, special.
Why /dev/tty0? What is it about /dev/tty0 which makes it better than
/dev/ttyS0, or /dev/lp0, or any other char device in /dev?

Yes, in YOUR situation /dev/tty0 makes sense. But general tools,
and init is one, should not make such arbitrary exceptions
if at all possible. It's a bad design.


>> I proposed a solution, and get no response. This is it:
>>
>>
>> ::respawn:/bin/run_sh_if_tty.sh
>>
>> where run_sh_if_tty.sh is
>>
>> #!/bin/sh
>> while ! tty >/dev/null 2>&1; do sleep 3600; done
>> exec sh "$@"
>>
>>
>>
>> In console=ttyS0 case, stdin will be /dev/ttyS0,
>> "tty" command exits with 0, and you fall into exec sh.
>>
>> In console= case, stdin will be /dev/null,
>> "tty" command exits with 1, and you sleep.
>>
>>
>> Is it ok for you? If not, why?
>
> Thnx for this. It works fine and I will probably use it. Maybe It would be
> good to FAQ it. But to be honest this script looks a bit hackish too

No, it is not hackish, it's _customized to your needs_. init is a general tool,
and therefore should not have special knowledge about /dev/tty0,
while shell scripts you start from it may very well be your own scripts,
with whatever customizations your situation (or your design ideas)
asks for.

--
vda
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