tty.c

/* tty -- print the path of the terminal connected to standard input
   Copyright (C) 1990-2002 Free Software Foundation, Inc.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
 
/* Displays "not a tty" if stdin is not a terminal.
   Displays nothing if -s option is given.
   Exit status 0 if stdin is a tty, 1 if not, 2 if usage error,
   3 if write error.
 
   Written by David MacKenzie <[email protected]>.  */
 
#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>
 
#include "system.h"
#include "closeout.h"
#include "error.h"
 
/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "tty"
 
#define AUTHORS "David MacKenzie"
 
/* The name under which this program was run. */
char *program_name;
 
/* If nonzero, return an exit status but produce no output. */
static int silent;
 
static struct option const longopts[] =
{
  {"silent", no_argument, NULL, 's'},
  {"quiet", no_argument, NULL, 's'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};
 
void
usage (int status)
{
  if (status != 0)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
         program_name);
  else
    {
      printf (_("Usage: %s [OPTION]...\n"), program_name);
      fputs (_("\
Print the file name of the terminal connected to standard input.\n\
\n\
  -s, --silent, --quiet   print nothing, only return an exit status\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    }
  exit (status);
}
 
int
main (int argc, char **argv)
{
  char *tty;
  int optc;
 
  program_name = argv[0];
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);
 
  close_stdout_set_status (3);
  atexit (close_stdout);
 
  silent = 0;
 
  while ((optc = getopt_long (argc, argv, "s", longopts, NULL)) != -1)
    {
      switch (optc)
    {
    case 0:
      break;
 
    case 's':
      silent = 1;
      break;
 
    case_GETOPT_HELP_CHAR;
 
    case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 
    default:
      usage (2);
    }
    }
 
  if (optind != argc)
    error (0, 0, _("ignoring all arguments"));
 
  tty = ttyname (0);
  if (!silent)
    {
      if (tty)
    puts (tty);
      else
    puts (_("not a tty"));
    }
 
  exit (isatty (0) ? 0 : 1);
}