No One Noticed the Cat

#if defined (NO_MAIN_ENV_ARG)
/* systems without third argument to main() */
int
main (argc, argv)
     int argc;
     char **argv;
#else /* !NO_MAIN_ENV_ARG */
int
main (argc, argv, env)
     int argc;
     char **argv, **env;
#endif /* !NO_MAIN_ENV_ARG */
{

  shell_initialized = 1;

  if (pretty_print_mode && interactive_shell)
    {
      internal_warning (_("pretty-printing mode ignored in interactive shells"));
      pretty_print_mode = 0;
    }
  if (pretty_print_mode)
    exit_shell (pretty_print_loop ());

  /* Read commands until exit condition. */
  reader_loop ();
  exit_shell (last_command_exit_value);
}

/* Read and execute commands until EOF is reached.  This assumes that
   the input source has already been initialized. */
int
reader_loop ()
{
  int our_indirection_level;
  COMMAND * volatile current_command;

  USE_VAR(current_command);

  current_command = (COMMAND *)NULL;

  our_indirection_level = ++indirection_level;

  if (just_one_command)
    reset_readahead_token ();

  while (EOF_Reached == 0)
    {

      if (read_command () == 0)
	{
  省略
	}
      else
	{
	  /* Parse error, maybe discard rest of stream if not interactive. */
	  if (interactive == 0)
	    EOF_Reached = EOF;
	}
      if (just_one_command)
	EOF_Reached = EOF;
    }
  indirection_level--;
  return (last_command_exit_value);
}

/* Read and parse a command, returning the status of the parse.  The command
   is left in the globval variable GLOBAL_COMMAND for use by reader_loop.
   This is where the shell timeout code is executed. */
int
read_command ()
{
  SHELL_VAR *tmout_var;
  int tmout_len, result;
  SigHandler *old_alrm;

  set_current_prompt_level (1);
  global_command = (COMMAND *)NULL;

  /* Only do timeouts if interactive. */
  tmout_var = (SHELL_VAR *)NULL;
  tmout_len = 0;
  old_alrm = (SigHandler *)NULL;

  if (interactive)
    {
      tmout_var = find_variable ("TMOUT");

      if (tmout_var && var_isset (tmout_var))
	{
	  tmout_len = atoi (value_cell (tmout_var));
	  if (tmout_len > 0)
	    {
	      old_alrm = set_signal_handler (SIGALRM, alrm_catcher);
	      alarm (tmout_len);
	    }
	}
    }

  QUIT;

  current_command_line_count = 0;
  result = parse_command ();

  if (interactive && tmout_var && (tmout_len > 0))
    {
      alarm(0);
      set_signal_handler (SIGALRM, old_alrm);
    }

  return (result);
}

/* Call the YACC-generated parser and return the status of the parse.
   Input is read from the current input stream (bash_input).  yyparse
   leaves the parsed command in the global variable GLOBAL_COMMAND.
   This is where PROMPT_COMMAND is executed. */
int
parse_command ()
{
  int r;

  need_here_doc = 0;
  run_pending_traps ();

  /* Allow the execution of a random command just before the printing
     of each primary prompt.  If the shell variable PROMPT_COMMAND
     is set then its value (array or string) is the command(s) to execute. */
  /* The tests are a combination of SHOULD_PROMPT() and prompt_again() 
     from parse.y, which are the conditions under which the prompt is
     actually printed. */
  if (interactive && bash_input.type != st_string && parser_expanding_alias() == 0)
    {
#if defined (READLINE)
      if (no_line_editing || (bash_input.type == st_stdin && parser_will_prompt ()))
#endif
        execute_prompt_command ();

      if (running_under_emacs == 2)
	send_pwd_to_eterm ();	/* Yuck */
    }

  current_command_line_count = 0;
  r = yyparse ();

  if (need_here_doc)
    gather_here_documents ();

  return (r);
}