src/tty.c

   1 /* tty -- print the name of the terminal connected to standard input
   2    Copyright (C) 1990-2005, 2008-2011 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 3 of the License, or
   7    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Displays "not a tty" if stdin is not a terminal.
  18    Displays nothing if -s option is given.
  19    Exit status 0 if stdin is a tty, 1 if not, 2 if usage error,
  20    3 if write error.
  21
  22    Written by David MacKenzie <djm@gnu.ai.mit.edu>.  */
  23
  24 #include <config.h>
  25 #include <stdio.h>
  26 #include <getopt.h>
  27 #include <sys/types.h>
  28
  29 #include "system.h"
  30 #include "error.h"
  31 #include "quote.h"
  32
  33 /* Exit statuses.  */
  34 enum
  35   {
  36     TTY_FAILURE = 2,
  37     TTY_WRITE_ERROR = 3
  38   };
  39
  40 /* The official name of this program (e.g., no `g' prefix).  */
  41 #define PROGRAM_NAME "tty"
  42
  43 #define AUTHORS proper_name ("David MacKenzie")
  44
  45 /* If true, return an exit status but produce no output. */
  46 static bool silent;
  47
  48 static struct option const longopts[] =
  49 {
  50   {"silent", no_argument, NULL, 's'},
  51   {"quiet", no_argument, NULL, 's'},
  52   {GETOPT_HELP_OPTION_DECL},
  53   {GETOPT_VERSION_OPTION_DECL},
  54   {NULL, 0, NULL, 0}
  55 };
  56
  57 void
  58 usage (int status)
  59 {
  60   if (status != EXIT_SUCCESS)
  61     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  62              program_name);
  63   else
  64     {
  65       printf (_("Usage: %s [OPTION]...\n"), program_name);
  66       fputs (_("\
  67 Print the file name of the terminal connected to standard input.\n\
  68 \n\
  69   -s, --silent, --quiet   print nothing, only return an exit status\n\
  70 "), stdout);
  71       fputs (HELP_OPTION_DESCRIPTION, stdout);
  72       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  73       emit_ancillary_info ();
  74     }
  75   exit (status);
  76 }
  77
  78 int
  79 main (int argc, char **argv)
  80 {
  81   char *tty;
  82   int optc;
  83
  84   initialize_main (&argc, &argv);
  85   set_program_name (argv[0]);
  86   setlocale (LC_ALL, "");
  87   bindtextdomain (PACKAGE, LOCALEDIR);
  88   textdomain (PACKAGE);
  89
  90   initialize_exit_failure (TTY_WRITE_ERROR);
  91   atexit (close_stdout);
  92
  93   silent = false;
  94
  95   while ((optc = getopt_long (argc, argv, "s", longopts, NULL)) != -1)
  96     {
  97       switch (optc)
  98         {
  99         case 's':
 100           silent = true;
 101           break;
 102
 103         case_GETOPT_HELP_CHAR;
 104
 105         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 106
 107         default:
 108           usage (TTY_FAILURE);
 109         }
 110     }
 111
 112   if (optind < argc)
 113     error (0, 0, _("extra operand %s"), quote (argv[optind]));
 114
 115   tty = ttyname (STDIN_FILENO);
 116   if (!silent)
 117     {
 118       if (tty)
 119         puts (tty);
 120       else
 121         puts (_("not a tty"));
 122     }
 123
 124   exit (isatty (STDIN_FILENO) ? EXIT_SUCCESS : EXIT_FAILURE);
 125 }