Re: disowning a process

[Davy Durham <pubaddr2@davyandbeth.com>]

Davy Durham wrote:

> Cool.. I looked at the daemon function and I might be able to use it..
>
> However, I compiled your code... seems to work.. but where is the 
> wait() done on the middle parrent so that it isn't left defunct?
>
I added "waitpid(pid,NULL,0);" after the outer-most if.. which is where 
the grand parent cleans up the pid of the intermediate parent. 

However, now trying the daemon() function..  which seems to work the 
same way.. it definately leaves a pid around.. so I guess you really 
need to do a wait() in the parent after forking.. however you don't know 
exactly which pid to wait for so you might be reaping some other child 
you've previously spawned.. 

So, for now I'm going to stick with the explicit double fork code.

Thanks!

> Steven Rostedt wrote:
>
>> Try man daemon.
>>
>> The way I use to do it was simply do a double fork. That is
>> (simplified)...
>>
>> if ((pid = fork()) < 0) {
>>     perror("fork");
>> } else if (!pid) {
>>     /* child */
>>     if ((pid = fork()) < 0) {
>>         perror("child fork");
>>         exit(-1);
>>     } if (pid) {
>>         /* child parent */
>>         /* Here we detach from the child */
>>         exit(0);
>>     }
>>     /* Now this code is a child running almost as a daemon
>>         with init as the parent. */
>>     setsid();
>>     /* Now the child is completely detached from the original
>>        parent */
>>     /* ... daemon code here ... */
>>     exit(0);
>> }
>>
>> /* parent code here */
>>
>> -- Steve
>>
>>  
>>
>
>
>
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