src/tty.c

   1 /* tty -- print the name of the terminal connected to standard input
   2    Copyright (C) 1990-2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 "error.h"
  32 #include "quote.h"
  33
  34 /* Exit statuses.  */
  35 enum
  36   {
  37     TTY_FAILURE = 2,
  38     TTY_WRITE_ERROR = 3
  39   };
  40
  41 /* The official name of this program (e.g., no `g' prefix).  */
  42 #define PROGRAM_NAME "tty"
  43
  44 #define AUTHORS "David MacKenzie"
  45
  46 /* The name under which this program was run. */
  47 char *program_name;
  48
  49 /* If true, return an exit status but produce no output. */
  50 static bool silent;
  51
  52 static struct option const longopts[] =
  53 {
  54   {"silent", no_argument, NULL, 's'},
  55   {"quiet", no_argument, NULL, 's'},
  56   {GETOPT_HELP_OPTION_DECL},
  57   {GETOPT_VERSION_OPTION_DECL},
  58   {NULL, 0, NULL, 0}
  59 };
  60
  61 void
  62 usage (int status)
  63 {
  64   if (status != EXIT_SUCCESS)
  65     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  66              program_name);
  67   else
  68     {
  69       printf (_("Usage: %s [OPTION]...\n"), program_name);
  70       fputs (_("\
  71 Print the file name of the terminal connected to standard input.\n\
  72 \n\
  73   -s, --silent, --quiet   print nothing, only return an exit status\n\
  74 "), stdout);
  75       fputs (HELP_OPTION_DESCRIPTION, stdout);
  76       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  77       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
  78     }
  79   exit (status);
  80 }
  81
  82 int
  83 main (int argc, char **argv)
  84 {
  85   char *tty;
  86   int optc;
  87
  88   initialize_main (&argc, &argv);
  89   program_name = argv[0];
  90   setlocale (LC_ALL, "");
  91   bindtextdomain (PACKAGE, LOCALEDIR);
  92   textdomain (PACKAGE);
  93
  94   initialize_exit_failure (TTY_WRITE_ERROR);
  95   atexit (close_stdout);
  96
  97   silent = false;
  98
  99   while ((optc = getopt_long (argc, argv, "s", longopts, NULL)) != -1)
 100     {
 101       switch (optc)
 102         {
 103         case 's':
 104           silent = true;
 105           break;
 106
 107         case_GETOPT_HELP_CHAR;
 108
 109         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 110
 111         default:
 112           usage (TTY_FAILURE);
 113         }
 114     }
 115
 116   if (optind < argc)
 117     error (0, 0, _("extra operand %s"), quote (argv[optind]));
 118
 119   tty = ttyname (STDIN_FILENO);
 120   if (!silent)
 121     {
 122       if (tty)
 123         puts (tty);
 124       else
 125         puts (_("not a tty"));
 126     }
 127
 128   exit (isatty (STDIN_FILENO) ? EXIT_SUCCESS : EXIT_FAIL);
 129 }