adv_cmds/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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifndef lint
  35 static const char copyright[] =
  36 "@(#) Copyright (c) 1988, 1993\n\
  37         The Regents of the University of California.  All rights reserved.\n";
  38 #endif /* not lint */
  39
  40 #ifndef lint
  41 #if 0
  42 static char sccsid[] = "@(#)tty.c       8.1 (Berkeley) 6/6/93";
  43 #endif
  44 #endif /* not lint */
  45
  46 #include <sys/cdefs.h>
  47 __FBSDID("$FreeBSD: src/usr.bin/tty/tty.c,v 1.9 2002/05/29 17:12:30 jmallett Exp $");
  48
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <unistd.h>
  52
  53 static void usage(void);
  54
  55 int
  56 main(int argc, char *argv[])
  57 {
  58         int ch, sflag;
  59         char *t;
  60
  61         sflag = 0;
  62         while ((ch = getopt(argc, argv, "s")) != -1)
  63                 switch (ch) {
  64                 case 's':
  65                         sflag = 1;
  66                         break;
  67                 case '?':
  68                 default:
  69                         usage();
  70                 }
  71
  72         t = ttyname(0);
  73         if (!sflag)
  74                 puts(t ? t : "not a tty");
  75         exit(t ? 0 : 1);
  76 }
  77
  78 static void
  79 usage(void)
  80 {
  81         fprintf(stderr, "usage: tty [-s]\n");
  82         exit(2);
  83 }