Example GRUB Module

argshow.c

/* argshow.c - test module for dynamic loading */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2003,2007  Free Software Foundation, Inc.
 *  Copyright (C) 2003  NIIBE Yutaka <gniibe@m17n.org>
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/types.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/err.h>
#include <grub/dl.h>
#include <grub/extcmd.h>
#include <grub/i18n.h>

GRUB_MOD_LICENSE ("GPLv3+");

static const struct grub_arg_option options[] = {
  {"string",  's', 0, N_("Option with a string argument"),   0, ARG_TYPE_STRING},
  {"integer", 'i', 0, N_("Option with an integer argument"), 0, ARG_TYPE_INT},
  {"option1", '1', 0, N_("Option 1 with no argument"),       0, ARG_TYPE_NONE},
  {"option2", '2', 0, N_("Option 2 with no argument"),       0, ARG_TYPE_NONE},
  {0, 0, 0, 0, 0, 0}
};

static grub_err_t
grub_cmd_argshow (grub_extcmd_context_t ctxt, int argc, char **args)
{
  struct grub_arg_list *state = ctxt->state;
  int i = 0;

  /* options */
  for (i=0; options[i].shortarg; i++)
    {
      grub_printf(_("option '-%c' '--%s' is "), options[i].shortarg, options[i].longarg);
      if (state[i].set)
        if (options[i].type == ARG_TYPE_STRING)
          grub_printf("'%s'\n", state[i].arg);
        else if (options[i].type == ARG_TYPE_INT)
          grub_printf("%lu\n", grub_strtoul (state[i].arg, 0, 0));
        else
          grub_printf(_("set\n"));
      else
        grub_printf(_("not set\n"));
    }

  /* positional parameters */
  if (argc)
    grub_printf ("%s\n", _("Positional parameters:"));
    for (i=0; i<argc; i++)
      grub_printf ("%d : %s\n", i, args[i]);

  return 0;
}

static grub_extcmd_t cmd;

GRUB_MOD_INIT(argshow)
{
  cmd = grub_register_extcmd ("argshow", grub_cmd_argshow, 0,
                              N_("[-s STRING] [-i INTEGER] [-1] [-2]"),
                              N_("Show given arguments"),
                              options);
}

GRUB_MOD_FINI(argshow)
{
  grub_unregister_extcmd (cmd);
}

Example Grub Module.md

This is an example Grub module that demonstrates how to add a command to Grub that can process command-line options and other parameters.

Makefile.core.def

AutoGen definitions Makefile.tpl;

module = {
  name = argshow;
  common = contrib/argshow/argshow.c;
};