Re: runit pblms on Mandrake

[Karthik M <k_mohanas@yahoo.com>]

Hi,

That's very interesting to know that some of the getty
like program do invoke setsid() internally and some of
them don't. This should be made standardised that all
of these programs should invoke setsid() internally.
AFAIK there is not mentioning of setsid() needed to be
invoked externally in the man pages for mingetty. :(
:(

I have another question which sprang up when playing
around with the scripts. 

"How does the init process know that a getty process
has died and it needs to be respawned ??"

possible solution:

Getty processes raising a signal such as SIGCHLD when
exiting but when a user logins, getty program uses a
/bin/login binary for user authentication and when the
user login it is either /bin/sh or /bin/bash [or
similar] shells that are in control. A getty process
cannot be observed from the 'ps -aux' output. So it is
not running at all after the user logins into the
system. So when the user logs out then it is the shell
that exits and not the getty process. 

But how does init detect that it needs to respawn a
getty process for that specific tty ??

thanx for all the help and guidance in my learning
process.

Karthik


--- Lukas Beeler <lb-lists@projectdream.org> wrote:
> * Karthik M <k_mohanas@yahoo.com>:
> > I searched thru the man page for mingetty and
> there
> > was no mentioning that it has to be the process
> group
> > leader and we had to invoke setsid() if we need to
> > invoke it seperately !! where do we get all these
> kind
> > of info for debugging such pblms ?? just out of
> > curiosity want to know so that i can search on my
> own
> > before posting it to mailing lists.
> 
> ptrace() mingetty using strace. You'll see that a
> system call
> returns EPERM (I don't remember which one). It's
> seldom that you
> get EPERM when running a program as root. Thus, i
> looked through
> the kernel source for this system call, and found
> out that EPERM
> is returned in case the program is not session
> leader. Finding
> out how to become session leader was a matter of
> quick googling.
> 
> -- 
> Today is the first day of the rest of our lives.
> http://www.suug.ch


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