CentOS - Jul 2009 - Init checking for processes that are configured to "respawn"

Hi folks,

I have a sophisticated question for which I can't find any hints on the 
web:

If you configure init (via /etc/inittab) to respawn processes (like the 
getty processes) when they exit - how often does init check for the 
existence of such a process? Does it check actively at all or does it 
rely on some kind of inter process communication?

I am not a programmer, so maybe the second question is completely 
nonsense. Any hint or help is appreciated.

Dirk

On 2009-07-07, at 6:17 AM, "Dirk H. Schulz"  
<dirk.schulz at kinzesberg.de> wrote:
> Hi folks,
>
> I have a sophisticated question for which I can't find any hints on  
> the
> web:
>
> If you configure init (via /etc/inittab) to respawn processes (like  
> the
> getty processes) when they exit - how often does init check for the
> existence of such a process? Does it check actively at all or does it
> rely on some kind of inter process communication?
I'd imagine it uses wait (man 2 wait) and/or waits for a SIGCHLD to be  
sent. The latter sent to it whenever a child process exits.

In either case, the spawned process does not need to be aware of how  
knit works under the hood.

HTH
Michael