Daemons - Using the process class?

[Wolfgang Alper]

Hello,
I am using commoncpp2-1.5.6 under linux.
I tried using the process class but it seems i miss a piece.
Basicallyl i would like to create a daemon (using linux) based on fork.
i thought i would have to call: Process::detach();
From the docs
"Detach current process into a daemon, posix only. Perhaps a similar method
can be used for creating win32 "services"?"

but this cannot work as it is defined as follows:
void Process::detach(void) { attach("/dev/null"); }

So it seems that :
void Process::attach (const char * devname )  
"Attach the current process to another device or i/o session. It is
deamonified and dissasociated with the prior parent process and controlling
terminal."
is the better choice.

But i still do not get it to work.
-What to pass as devname?
-How do it get the PID to know wether i am the child or parent?
-How can i pass parameter (like waitpid) to decide wether the parent wants to
wait for the child or not?

I am sure i missunderstood something, so if anyone could give an example on
how to use this class, this would be great.

Thanks

Wolfgang





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[Wolfgang Alper]

Hello,

Sorry, i just realized that the following is obviously wrong:
> but this cannot work as it is defined as follows:
> void Process::detach(void) { attach("/dev/null"); }

This calls attach with "dev/null".

Anyway, i still do not get it to work so any help is apprecicated.

Example:
main() {
  cout << "before creating the daemon" <<  endl;
  // ? how to setup the parent to wait (or not) for the child?
  // cannot use detach because it would close all handles of the child.
  Process::attach("what goes here?");
  If ("what goes here?") {
    char buffer[32];
    cout << "i am the child" << endl;
    cin.getline(buffer, sizeof(buffer));
    cout << "Child: You entered:" << buffer << "\nDone:" << endl;  
    exit(0);
  } else {
    cout << "i am the parent - Done" << endl;    
    exit(0);
  }
}

Regards

Wolfgang


Am Mittwoch, 9. Mai 2007 17:21 schrieb Wolfgang Alper:

> Hello,
> I am using commoncpp2-1.5.6 under linux.
> I tried using the process class but it seems i miss a piece.
> Basicallyl i would like to create a daemon (using linux) based on fork.
> i thought i would have to call: Process::detach();
> From the docs
> "Detach current process into a daemon, posix only. Perhaps a similar method
> can be used for creating win32 "services"?"
>
> but this cannot work as it is defined as follows:
> void Process::detach(void) { attach("/dev/null"); }
>
> So it seems that :
> void Process::attach (const char * devname )
> "Attach the current process to another device or i/o session. It is
> deamonified and dissasociated with the prior parent process and controlling
> terminal."
> is the better choice.
>
> But i still do not get it to work.
> -What to pass as devname?
> -How do it get the PID to know wether i am the child or parent?
> -How can i pass parameter (like waitpid) to decide wether the parent wants
> to wait for the child or not?
>
> I am sure i missunderstood something, so if anyone could give an example on
> how to use this class, this would be great.
>
> Thanks
>
> Wolfgang
>
>
>
>
>
> _______________________________________________
> Bug-commoncpp mailing list
> Bug-commoncpp@...
> http://lists.gnu.org/mailman/listinfo/bug-commoncpp

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[David Sugar-2]

What attach does is dissasociate the controlling terminal and
potentially associate with a new one under a new process group.  The
same code is reused for detach, which does the dissociate and single
fork on some platforms, and a dual fork on others.

Wolfgang Alper wrote:

> Hello,
>
> Sorry, i just realized that the following is obviously wrong:
>> but this cannot work as it is defined as follows:
>> void Process::detach(void) { attach("/dev/null"); }
>
> This calls attach with "dev/null".
>
> Anyway, i still do not get it to work so any help is apprecicated.
>
> Example:
> main() {
>   cout << "before creating the daemon" <<  endl;
>   // ? how to setup the parent to wait (or not) for the child?
>   // cannot use detach because it would close all handles of the child.
>   Process::attach("what goes here?");
>   If ("what goes here?") {
>     char buffer[32];
>     cout << "i am the child" << endl;
>     cin.getline(buffer, sizeof(buffer));
>     cout << "Child: You entered:" << buffer << "\nDone:" << endl;  
>     exit(0);
>   } else {
>     cout << "i am the parent - Done" << endl;    
>     exit(0);
>   }
> }
>
> Regards
>
> Wolfgang
>
>
> Am Mittwoch, 9. Mai 2007 17:21 schrieb Wolfgang Alper:
>> Hello,
>> I am using commoncpp2-1.5.6 under linux.
>> I tried using the process class but it seems i miss a piece.
>> Basicallyl i would like to create a daemon (using linux) based on fork.
>> i thought i would have to call: Process::detach();
>> From the docs
>> "Detach current process into a daemon, posix only. Perhaps a similar method
>> can be used for creating win32 "services"?"
>>
>> but this cannot work as it is defined as follows:
>> void Process::detach(void) { attach("/dev/null"); }
>>
>> So it seems that :
>> void Process::attach (const char * devname )
>> "Attach the current process to another device or i/o session. It is
>> deamonified and dissasociated with the prior parent process and controlling
>> terminal."
>> is the better choice.
>>
>> But i still do not get it to work.
>> -What to pass as devname?
>> -How do it get the PID to know wether i am the child or parent?
>> -How can i pass parameter (like waitpid) to decide wether the parent wants
>> to wait for the child or not?
>>
>> I am sure i missunderstood something, so if anyone could give an example on
>> how to use this class, this would be great.
>>
>> Thanks
>>
>> Wolfgang
>>
>>
>>
>>
>>
>> _______________________________________________
>> Bug-commoncpp mailing list
>> Bug-commoncpp@...
>> http://lists.gnu.org/mailman/listinfo/bug-commoncpp
>
>
> _______________________________________________
> Bug-commoncpp mailing list
> Bug-commoncpp@...
> http://lists.gnu.org/mailman/listinfo/bug-commoncpp

[dyfet.vcf]

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n:Sugar;David
org:GNU Telephony
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