examples/loadables/tty.c

   1 /* tty - return terminal name */
   2
   3 /* See Makefile for compilation details. */
   4
   5 /*
   6    Copyright (C) 1999-2009 Free Software Foundation, Inc.
   7
   8    This file is part of GNU Bash.
   9    Bash is free software: you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation, either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    Bash is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "config.h"
  24
  25 #include <stdio.h>
  26 #include "builtins.h"
  27 #include "shell.h"
  28 #include "bashgetopt.h"
  29 #include "common.h"
  30
  31 extern char *ttyname ();
  32
  33 int
  34 tty_builtin (list)
  35      WORD_LIST *list;
  36 {
  37   int opt, sflag;
  38   char *t;
  39
  40   reset_internal_getopt ();
  41   sflag = 0;
  42   while ((opt = internal_getopt (list, "s")) != -1)
  43     {
  44       switch (opt)
  45         {
  46         case 's':
  47           sflag = 1;
  48           break;
  49         default:
  50           builtin_usage ();
  51           return (EX_USAGE);
  52         }
  53     }
  54   list = loptend;
  55
  56   t = ttyname (0);
  57   if (sflag == 0)
  58     puts (t ? t : "not a tty");
  59   return (t ? EXECUTION_SUCCESS : EXECUTION_FAILURE);
  60 }
  61
  62 char *tty_doc[] = {
  63         "Display terminal name.",
  64         "",
  65         "tty writes the name of the terminal that is opened for standard",
  66         "input to standard output.  If the `-s' option is supplied, nothing",
  67         "is written; the exit status determines whether or not the standard",
  68         "input is connected to a tty.",
  69         (char *)NULL
  70 };
  71
  72 /* The standard structure describing a builtin command.  bash keeps an array
  73    of these structures. */
  74 struct builtin tty_struct = {
  75         "tty",                  /* builtin name */
  76         tty_builtin,            /* function implementing the builtin */
  77         BUILTIN_ENABLED,        /* initial flags for builtin */
  78         tty_doc,                /* array of long documentation strings. */
  79         "tty [-s]",             /* usage synopsis; becomes short_doc */
  80         0                       /* reserved for internal use */
  81 };