Re: Creating and killing processes

From: Kasper Dupont (kasperd_at_daimi.au.dk)
Date: 03/18/04 

Date: Thu, 18 Mar 2004 13:15:37 +0100

Jens wrote:
>
> Question 1: Isn't it possible to launch an application from another
> application and then get completely detached just like Windows? This would
> probably resolve my problems.

fork twice let the intermediate process terminate
and have the parent wait at once for the
intermediate process.

>
> Question 2: Any clue as to why it get stuck and doesn't release the PID
> completely?

It is a zombie. A dead process cannot remove itself
from the task list, somebody else have to do. On
Unix the parent is responsible to do that, it is
done with one of the wait system calls that can do
a couple of things:

1) Wait for a child to terminate.
2) Collect the exist status of the child.
3) Remove the child from the task list.

The execve call doesn't change the parent/child
relationship. It only replaces the process image
of one of the processes with a new executable.

http://www.daimi.au.dk/~kasperd/comp.os.linux.development.faq.html#zombie 

-- 
Kasper Dupont -- der bruger for meget tid paa usenet.
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