...
sysdb=shm_open(path,O_CREAT|O_RDWR,S_IRWXO|S_IRWXG|S_IRWXU);
if (sysdb==-1)
 {
   perror("main:shm_open system database error");
   exit(1);
 }
 if(ftruncate(sysdb,SYSDB_SIZE)==-1)
   {
      perror("main:ftruncate sysdb failure");
      exit(1);
   }
   sysdb_addr=(caddr_t)mmap(0,SYSDB_SIZE,PROT_READ|PROT_WRITE,MAP_SHARED,\
              sysdb,0);
   if(sysdb_addr==(caddr_t)-1)
   {
      perror("main:system database mmap error");
      exit(1);
   }
   sysdb_header=(DB_HEADER *)sysdb_addr;
  
  ...