Greetings;

I am trying to create a background application (starts with system startup, and keeps running in the background ) under linux. the only solution i found is to make it as daemon.
searching the internet about how to create a daemon , I built a small app around my findings.

Qt Code: 
  1. #include <stdlib.h>
  2. #include <stdio.h>
  3. #include <fcntl.h>
  4. #include <signal.h>
  5. #include <unistd.h>
  6. #include "globaldefs.h"
  7.  
  8. void log_message(char *filename,char *message)
  9. {
  10.     FILE *logfile;
  11.     logfile=fopen(filename,"a");
  12.     if(!logfile) return;
  13.     fprintf(logfile,"%s\n",message);
  14.     fclose(logfile);
  15. }
  16.  
  17.  
  18. /**
  19.   a signal handler for the Linux signals sent to daemon process,
  20.   for more signals, refer to http://www.comptechdoc.org/os/linux/programming/linux_pgsignals.html
  21.   */
  22. void signal_handler(int sig)
  23. {
  24.     switch(sig) {
  25.     case SIGHUP:
  26.         log_message(LOG_FILE,"hangup signal catched");
  27.         break;
  28.     case SIGTERM:
  29.         log_message(LOG_FILE,"terminate signal catched");
  30.         break;
  31.     }
  32. }
  33.  
  34. /**
  35.   create background process out of the application, source code taken from: http://www.enderunix.org/docs/eng/daemon.php
  36.   with some minor modifications
  37.   */
  38. void init_daemon()
  39. {
  40.     int i,lfp;
  41.     char str[10];
  42.     if(getppid()==1)
  43.         return; /* already a daemon */
  44.     i=fork();
  45.     if (i<0)
  46.         exit(1); /* fork error */
  47.     if (i>0)
  48.         exit(0); /* parent exits */
  49.  
  50.     /* child (daemon) continues */
  51.     setsid(); /* obtain a new process group */
  52.  
  53.     for (i=getdtablesize();i>=0;--i)
  54.         close(i); /* close all descriptors */
  55.     i=open("/dev/null",O_RDWR); dup(i); dup(i); /* handle standart I/O */
  56.  
  57.     umask(027); /* set newly created file permissions */
  58.  
  59.     chdir(RUNNING_DIR); /* change running directory */
  60.     lfp=open(LOCK_FILE,O_RDWR|O_CREAT,0640);
  61.     if (lfp<0)
  62.         exit(1); /* can not open */
  63.     if (lockf(lfp,F_TLOCK,0)<0)
  64.         exit(0); /* can not lock */
  65.     /* first instance continues */
  66.     sprintf(str,"%d\n",getpid());
  67.     write(lfp,str,strlen(str)); /* record pid to lockfile */
  68.     signal(SIGCHLD,SIG_IGN); /* ignore child */
  69.     signal(SIGTSTP,SIG_IGN); /* ignore tty signals */
  70.     signal(SIGTTOU,SIG_IGN);
  71.     signal(SIGTTIN,SIG_IGN);
  72.     signal(SIGHUP,signal_handler); /* catch hangup signal */
  73.     signal(SIGTERM,signal_handler); /* catch kill signal */
  74. }
  75. int main(int argc, char *argv[])
  76. {
  77.     // first, create the daemon
  78.     init_daemon();
  79.     QCoreApplication a(argc, argv);
  80.  
  81.     return a.exec();
  82. }
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the code doesn't handle signals (for example, a termination signal). So, when I run it from the command line, and try to kill it, it refuses to get killed!!! the only way to kill the process is to restart my machine!!
I really suspect that creating a QCoreApplication instance in the main method forks a new process other than the one i forked in the init_daemom() method.
When I try to debug the application. it fails tp fork a new process thus exit() is issued and the debugging session terminates.

I am using Qt 4.5 under ubuntu 9.04
What am I missing? can there be anything done to make my Qt application run as a daemon process ?? Am i using a wrong way to do so?

thanks in advance;