On Friday 18 May 2007 19:00, David Daney wrote:
> >> ttyS0::askfirst:-/bin/sh
> >>
> >> That will open the shell on a device that can be a controlling tty
> >> (/dev/ttyS0).
> >
> > Why shouldn't you be able to use console (or ""), so that it follows the
> > console wherever that is? (ttyS0, ttyS1, or a real linux virtual
> > console).
> >
> > Like I said, the documentation says the above is an implicit rule if you
> > have no inittab. The code appears to agree.
>
> You have a choice.
>
> If you want to suppress the bothersome message and be able to send
> SIGINT to a process by pressing a key (typically ^C) do it my way.
>
> If you want the behavior obtained by doing it your way, change nothing.
>
> If you want all this documented somewhere, patches are welcome.
I think that there is indeed an understandable desire to start
shell on the console and yet to have a ctty (have working ^C).
Main reason is that this will automatically start shell on
serial line or Linux vt - whichever is configured as console
for the kernel. Otherwise, it's sort of not trivial where
the console is.
IOW: I think these complaints will never stop unless something
is done about this.
I decided to add an applet which helps with that. It's in svn now
in "shells" section, it's called cttyhack and it has a nice (I hope)
help text which explains its purpose:
config CTTYHACK
bool "cttyhack"
default n
help
One common problem reported on the mailing list is "can't access tty;
job control turned off" error message which typically appears when
one tries to use shell with stdin/stdout opened to /dev/console.
This device is special - it cannot be a controlling tty.
Proper solution is to use correct device instead of /dev/console.
cttyhack provides "quick and dirty" solution to this problem.
It analyzes stdin with various ioctls, trying to determine whether
it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
If it detects one, it closes stdin/out/err and reopens that device.
Then it executes given program. Usage example for /etc/inittab
(for busybox init):
::respawn:/bin/cttyhack /bin/sh
What you guys think about it?
--
vda
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