Re: What is needed to run a tool like a daemon?

[Saso Kiselkov]

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Sure it's unportable, which is why I always include a custom
implementation of daemon() with my code which works on most *nixes :-).
After reading the message though I realize I misunderstood it.

What's most likely screwing up is that the process doesn't de-register
from the name server. Maybe a simple atexit() or signal() handler would
do the trick.

German: you do try this as a test whether the name is being unregistered:

void
dereg_name (void)
{
  // deregistration code here
  ...

  // to make sure we know that deregistration succeeded
  // even when we have no controlling terminal
  FILE *fp = fopen ("/tmp/test_dereg", "wb");
  fprintf (fp, "Deregistered name\n");
  fclose (fp);
}

void
handle_sig (int signum)
{
  exit (EXIT_SUCCESS);
}

int
main (int argc, char *argv[])
{
  ...
  signal (SIGINT, handle_sig);
  signal (SIGTERM, handle_sig);
  atexit (dereg_name);
  ...
}

I hope I'm not completely missing the point again...

BR,
- --
Saso

Richard Frith-Macdonald wrote:
> On 3 Dec 2009, at 07:34, Saso Kiselkov wrote:
> 
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>> And what's stopping you from simply forking into the background? Like
>> with the following:
>>
>> if (daemon (0, 0) == -1)
>>  {
>>    NSLog (@"Error daemonizing: %s", strerror (errno));
>>    exit (EXIT_FAILURE);
>>  }
> 
> I don't think that addresses the issue of registering a name.
> 
> Perhaps more importantly though, the code above has the problem of 'daemon()' 
> being severely unportable.
> 
> In GNUstep you should use NSTask to portably create a subprocess.
> 
> The gdnc tool (base/Tools/gdnc.m) provides an example of a process which 
> makes itsself be a daemon in a portable manner.
> 
> 

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