src/tty.c

   1 /* tty -- print the path of the terminal connected to standard input
   2    Copyright (C) 90, 91, 92, 93, 94, 1995 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
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, 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 "version.h"
  32 #include "error.h"
  33
  34 static void usage __P ((int status));
  35
  36 /* The name under which this program was run. */
  37 char *program_name;
  38
  39 /* If nonzero, return an exit status but produce no output. */
  40 static int silent;
  41
  42 /* If nonzero, display usage information and exit.  */
  43 static int show_help;
  44
  45 /* If nonzero, print the version on standard output and exit.  */
  46 static int show_version;
  47
  48 static struct option const longopts[] =
  49 {
  50   {"help", no_argument, &show_help, 1},
  51   {"silent", no_argument, NULL, 's'},
  52   {"quiet", no_argument, NULL, 's'},
  53   {"version", no_argument, &show_version, 1},
  54   {NULL, 0, NULL, 0}
  55 };
  56
  57 void
  58 main (int argc, char **argv)
  59 {
  60   char *tty;
  61   int optc;
  62
  63   program_name = argv[0];
  64   setlocale (LC_ALL, "");
  65   bindtextdomain (PACKAGE, LOCALEDIR);
  66   textdomain (PACKAGE);
  67
  68   silent = 0;
  69
  70   while ((optc = getopt_long (argc, argv, "s", longopts, (int *) 0)) != EOF)
  71     {
  72       switch (optc)
  73         {
  74         case 0:
  75           break;
  76
  77         case 's':
  78           silent = 1;
  79           break;
  80
  81         default:
  82           usage (2);
  83         }
  84     }
  85
  86   if (show_version)
  87     {
  88       printf ("tty - %s\n", version_string);
  89       exit (0);
  90     }
  91
  92   if (show_help)
  93     usage (0);
  94
  95   if (optind != argc)
  96     usage (2);
  97
  98   tty = ttyname (0);
  99   if (!silent)
 100     {
 101       if (tty)
 102         puts (tty);
 103       else
 104         puts (_("not a tty"));
 105
 106       if (ferror (stdout) || fclose (stdout) == EOF)
 107         error (3, errno, _("standard output"));
 108     }
 109
 110   exit (isatty (0) ? 0 : 1);
 111 }
 112
 113 static void
 114 usage (int status)
 115 {
 116   if (status != 0)
 117     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 118              program_name);
 119   else
 120     {
 121       printf (_("Usage: %s [OPTION]...\n"), program_name);
 122       printf (_("\
 123 Print the file name of the terminal connected to standard input.\n\
 124 \n\
 125   -s, --silent, --quiet   print nothing, only return an exit status\n\
 126       --help              display this help and exit\n\
 127       --version           output version information and exit\n\
 128 "));
 129     }
 130   exit (status);
 131 }