parameters in main()

[pnxi]

what does the parameters mean in the main() function, and how to use this kind of command parameters?

int main(int argc, char * argv[])
{
  
   char message[20];

   if(argc<2)
   {
	   printf("Fetal error: Too few arguments!\n");
	   exit(0);
   }
   while(fgets(message, 20, stdin) != NULL)
   {
      if( strncmp(message, "TERMINATE", 9) == 0)
      {
            fprintf(stderr, "Node %s forwarding on : %s\n", argv[1], message);
	    fprintf(stderr, "Node %s terminating\n", argv[1]);
            fprintf(stdout, "%s", message);
	    exit(1);
      }
      sleep(1);
      if(*message == *argv[1])
      {
         fprintf(stderr,"Node %s is keeping : %s\n", argv[1], message);
         fprintf(stderr,"That's for me!\n");
      }
      else 
      {
        
            fprintf(stderr,"Node %s forwarding on : %s\n", argv[1], message);
	    fprintf(stdout, "%s", message);
            fprintf(stderr,":\n");
         
      }
      
   }
   return 0;
}

[rotis23]

this is a good ref:

http://www.acm.uiuc.edu/webmonkeys/book/c_guide/

look at functions/program startup.