const char* fmt_info()
  {
       return "It is really cool format!";
  }
  

       # gcc -O2 -fPIC -c module.c
       # gcc -shared -o module.so module.o
  

  #include <unistd.h>
  #include <string.h>
  #include <errno.h>
  #include <dlfcn.h>

  #define PATH_LENGTH 256
      
  int main(int argc, char * argv[])
  {
      char path[PATH_LENGTH], *msg = NULL;
      const char* (*fmt)();
      void *module;
      
      getcwd(path, PATH_LENGTH);
      strcat(path, "/");
      strcat(path, "module.so");

      /* Load module */
      module = dlopen(path, RTLD_NOW);
      
      /* Error ! */
      if(!module)
      {
          msg = dlerror();

          if(msg != NULL)
	  {
              dlclose(module);
              exit(1);
          }
      }

      /* Try to resolve function "fmt_info()" */
      fmt = dlsym(module, "fmt_info");

      msg = dlerror();

      if(msg != NULL)
      {
          perror(msg);
          dlclose(module);
          exit(1);
      }
      
      /* call fmt_info() through a pointer*/
      printf("%s\n", fmt());

      /* close module */
      if(dlclose(module))
      {
          perror("error");
          exit(1);
      }
      
      return 0;
  }
  
  # gcc -o test main.c -ldl
  # ./test
  It is really cool format!
  #