src/tty.c

   1 /* tty -- print the path of the terminal connected to standard input
   2    Copyright (C) 1990-2002 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Displays "not a tty" if stdin is not a terminal.
  19    Displays nothing if -s option is given.
  20    Exit status 0 if stdin is a tty, 1 if not, 2 if usage error,
  21    3 if write error.
  22
  23    Written by David MacKenzie <djm@gnu.ai.mit.edu>.  */
  24
  25 #include <config.h>
  26 #include <stdio.h>
  27 #include <getopt.h>
  28 #include <sys/types.h>
  29
  30 #include "system.h"
  31 #include "closeout.h"
  32 #include "error.h"
  33
  34 /* The official name of this program (e.g., no `g' prefix).  */
  35 #define PROGRAM_NAME "tty"
  36
  37 #define AUTHORS "David MacKenzie"
  38
  39 /* The name under which this program was run. */
  40 char *program_name;
  41
  42 /* If nonzero, return an exit status but produce no output. */
  43 static int silent;
  44
  45 static struct option const longopts[] =
  46 {
  47   {"silent", no_argument, NULL, 's'},
  48   {"quiet", no_argument, NULL, 's'},
  49   {GETOPT_HELP_OPTION_DECL},
  50   {GETOPT_VERSION_OPTION_DECL},
  51   {NULL, 0, NULL, 0}
  52 };
  53
  54 void
  55 usage (int status)
  56 {
  57   if (status != 0)
  58     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  59              program_name);
  60   else
  61     {
  62       printf (_("Usage: %s [OPTION]...\n"), program_name);
  63       fputs (_("\
  64 Print the file name of the terminal connected to standard input.\n\
  65 \n\
  66   -s, --silent, --quiet   print nothing, only return an exit status\n\
  67 "), stdout);
  68       fputs (HELP_OPTION_DESCRIPTION, stdout);
  69       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  70       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
  71     }
  72   exit (status);
  73 }
  74
  75 int
  76 main (int argc, char **argv)
  77 {
  78   char *tty;
  79   int optc;
  80
  81   program_name = argv[0];
  82   setlocale (LC_ALL, "");
  83   bindtextdomain (PACKAGE, LOCALEDIR);
  84   textdomain (PACKAGE);
  85
  86   close_stdout_set_status (3);
  87   atexit (close_stdout);
  88
  89   silent = 0;
  90
  91   while ((optc = getopt_long (argc, argv, "s", longopts, NULL)) != -1)
  92     {
  93       switch (optc)
  94         {
  95         case 0:
  96           break;
  97
  98         case 's':
  99           silent = 1;
 100           break;
 101
 102         case_GETOPT_HELP_CHAR;
 103
 104         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 105
 106         default:
 107           usage (2);
 108         }
 109     }
 110
 111   if (optind != argc)
 112     error (0, 0, _("ignoring all arguments"));
 113
 114   tty = ttyname (0);
 115   if (!silent)
 116     {
 117       if (tty)
 118         puts (tty);
 119       else
 120         puts (_("not a tty"));
 121     }
 122
 123   exit (isatty (0) ? 0 : 1);
 124 }