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
  24 static const struct grub_arg_option options[] =
  25   {
  26     {0, 'n', 0, "do not output the trailing newline", 0, 0},
  27     {0, 'e', 0, "enable interpretation of backslash escapes", 0, 0},
  28     {0, 0, 0, 0, 0, 0}
  29   };
  30
  31 static grub_err_t
  32 grub_cmd_echo (grub_extcmd_t cmd, int argc, char **args)
  33 {
  34   struct grub_arg_list *state = cmd->state;
  35   int newline = 1;
  36   int i;
  37
  38   /* Check if `-n' was used.  */
  39   if (state[0].set)
  40     newline = 0;
  41
  42   for (i = 0; i < argc; i++)
  43     {
  44       char *arg = *args;
  45       args++;
  46
  47       while (*arg)
  48         {
  49           /* In case `-e' is used, parse backslashes.  */
  50           if (*arg == '\\' && state[1].set)
  51             {
  52               arg++;
  53               if (*arg == '\0')
  54                 break;
  55
  56               switch (*arg)
  57                 {
  58                 case '\\':
  59                   grub_printf ("\\");
  60                   break;
  61
  62                 case 'a':
  63                   grub_printf ("\a");
  64                   break;
  65
  66                 case 'c':
  67                   newline = 0;
  68                   break;
  69
  70                 case 'f':
  71                   grub_printf ("\f");
  72                   break;
  73
  74                 case 'n':
  75                   grub_printf ("\n");
  76                   break;
  77
  78                 case 'r':
  79                   grub_printf ("\r");
  80                   break;
  81
  82                 case 't':
  83                   grub_printf ("\t");
  84                   break;
  85
  86                 case 'v':
  87                   grub_printf ("\v");
  88                   break;
  89                 }
  90               arg++;
  91               continue;
  92             }
  93
  94           /* This was not an escaped character, or escaping is not
  95              enabled.  */
  96           grub_printf ("%c", *arg);
  97           arg++;
  98         }
  99
 100       /* If another argument follows, insert a space.  */
 101       if (i != argc - 1)
 102         grub_printf (" " );
 103     }
 104
 105   if (newline)
 106     grub_printf ("\n");
 107
 108   return 0;
 109 }
 110
 111 static grub_extcmd_t cmd;
 112 \f
 113 GRUB_MOD_INIT(echo)
 114 {
 115   cmd = grub_register_extcmd ("echo", grub_cmd_echo, GRUB_COMMAND_FLAG_BOTH,
 116                               "echo [-e|-n] STRING", "Display a line of text.",
 117                               options);
 118 }
 119
 120 GRUB_MOD_FINI(echo)
 121 {
 122   grub_unregister_extcmd (cmd);
 123 }