usr.bin/tty/tty.c

   1 /*
   2  * Copyright (c) 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#) Copyright (c) 1988, 1993 The Regents of the University of California.  All rights reserved.
  30  * @(#)tty.c    8.1 (Berkeley) 6/6/93
  31  * $FreeBSD: src/usr.bin/tty/tty.c,v 1.4.2.1 2001/07/30 10:16:47 dd Exp $
  32  * $DragonFly: src/usr.bin/tty/tty.c,v 1.4 2004/12/23 15:17:21 liamfoy Exp $
  33  */
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <unistd.h>
  38
  39 static void     usage(void);
  40
  41 int
  42 main(int argc, char **argv)
  43 {
  44         int ch, sflag;
  45         char *t;
  46
  47         sflag = 0;
  48         while ((ch = getopt(argc, argv, "s")) != -1)
  49                 switch(ch) {
  50                 case 's':
  51                         sflag = 1;
  52                         break;
  53                 case '?':
  54                 default:
  55                         usage();
  56                 }
  57
  58         t = ttyname(0);
  59         if (!sflag)
  60                 puts(t ? t : "not a tty");
  61         exit(t ? 0 : 1);
  62 }
  63
  64 static void
  65 usage(void)
  66 {
  67         fprintf(stderr, "usage: tty [-s]\n");
  68         exit(2);
  69 }