gcc-you can use this code to learn something about gcc, and inquire further into linux,

				f (char *p)				{				  char c;								  c = *++p;				  if (c != ' ')				    return 0;				  for (;;)				    {				      c = *p;				      if (g (c))					p++;				      else					{					  if (c == ' ')					    break;					  else					    return 0;					}				    }				  return 1;				}