[CentOS] Init checking for processes that are configured to respawn

[Dirk H. Schulz]

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

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Re: [CentOS] Init checking for processes that are configured to respawn

[Michael Kralka]

On 2009-07-07, at 6:17 AM, Dirk H. Schulz  
dirk.sch...@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
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