Re: disowning a process

[Davy Durham <pubaddr2@davyandbeth.com>]

Alan Cox wrote:

>On Gwe, 2005-05-27 at 19:55, Davy Durham wrote:
>  
>
>>Cool.. I looked at the daemon function and I might be able to use it..
>>    
>>
>
>Using daemon() is generally wise - it is basically a double fork and
>then one exits so that the orphan child becomes owned by init. However
>it also knows about platform specific considerations like setpgrp v
>setsid, whether an ioctl must be done to disown the controlling tty etc
>which can be fairly OS generation specific.
>  
>

Well, when I tried using it in a program with some sleeps to test.. I 
noticed that the intermediate process that daemon creates is not cleaned 
up with a wait() call (so I see a defunct process in the ps listing).

If I manually do the double fork() then I can call waitpid() myself for 
the pid that I know it spawned.   But if I just call wait() after 
calling daemon, then I don't know if I just cleaned up the pid it 
spawned (do I?), or some other previously spawned one (for perhaps 
totally different reasons)..

For my specifics it may not be a problem, but I guess I'm just whining 
about the fact that daemon() doesn't clean it up itself (or can it?)

Thanks much,
    Davy