commands/echo.c

   1 /* echo.c - Command to display a line of text  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2006,2007  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/dl.h>
  21 #include <grub/misc.h>
  22 #include <grub/extcmd.h>
  23 #include <grub/i18n.h>
  24
  25 static const struct grub_arg_option options[] =
  26   {
  27     {0, 'n', 0, N_("Do not output the trailing newline."), 0, 0},
  28     {0, 'e', 0, N_("Enable interpretation of backslash escapes."), 0, 0},
  29     {0, 0, 0, 0, 0, 0}
  30   };
  31
  32 static grub_err_t
  33 grub_cmd_echo (grub_extcmd_t cmd, int argc, char **args)
  34 {
  35   struct grub_arg_list *state = cmd->state;
  36   int newline = 1;
  37   int i;
  38
  39   /* Check if `-n' was used.  */
  40   if (state[0].set)
  41     newline = 0;
  42
  43   for (i = 0; i < argc; i++)
  44     {
  45       char *arg = *args;
  46       args++;
  47
  48       while (*arg)
  49         {
  50           /* In case `-e' is used, parse backslashes.  */
  51           if (*arg == '\\' && state[1].set)
  52             {
  53               arg++;
  54               if (*arg == '\0')
  55                 break;
  56
  57               switch (*arg)
  58                 {
  59                 case '\\':
  60                   grub_printf ("\\");
  61                   break;
  62
  63                 case 'a':
  64                   grub_printf ("\a");
  65                   break;
  66
  67                 case 'c':
  68                   newline = 0;
  69                   break;
  70
  71                 case 'f':
  72                   grub_printf ("\f");
  73                   break;
  74
  75                 case 'n':
  76                   grub_printf ("\n");
  77                   break;
  78
  79                 case 'r':
  80                   grub_printf ("\r");
  81                   break;
  82
  83                 case 't':
  84                   grub_printf ("\t");
  85                   break;
  86
  87                 case 'v':
  88                   grub_printf ("\v");
  89                   break;
  90                 }
  91               arg++;
  92               continue;
  93             }
  94
  95           /* This was not an escaped character, or escaping is not
  96              enabled.  */
  97           grub_printf ("%c", *arg);
  98           arg++;
  99         }
 100
 101       /* If another argument follows, insert a space.  */
 102       if (i != argc - 1)
 103         grub_printf (" " );
 104     }
 105
 106   if (newline)
 107     grub_printf ("\n");
 108
 109   return 0;
 110 }
 111
 112 static grub_extcmd_t cmd;
 113 \f
 114 GRUB_MOD_INIT(echo)
 115 {
 116   cmd = grub_register_extcmd ("echo", grub_cmd_echo, GRUB_COMMAND_FLAG_BOTH,
 117                               N_("[-e|-n] STRING"), N_("Display a line of text."),
 118                               options);
 119 }
 120
 121 GRUB_MOD_FINI(echo)
 122 {
 123   grub_unregister_extcmd (cmd);
 124 }