/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 * 4. 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
30#ifndef lint
31static const char copyright[] =
32"@(#) Copyright (c) 1988, 1993\n\
33	The Regents of the University of California.  All rights reserved.\n";
34#endif /* not lint */
35
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)tty.c	8.1 (Berkeley) 6/6/93";
39#endif
40#endif /* not lint */
41
42#include <sys/cdefs.h>
43__FBSDID("$FreeBSD$");
44
45#include <stdio.h>
46#include <stdlib.h>
47#include <unistd.h>
48
49static void usage(void);
50
51int
52main(int argc, char *argv[])
53{
54	int ch, sflag;
55	char *t;
56
57	sflag = 0;
58	while ((ch = getopt(argc, argv, "s")) != -1)
59		switch (ch) {
60		case 's':
61			sflag = 1;
62			break;
63		case '?':
64		default:
65			usage();
66		}
67
68	t = ttyname(0);
69	if (!sflag)
70		puts(t ? t : "not a tty");
71	exit(t ? 0 : 1);
72}
73
74static void
75usage(void)
76{
77	fprintf(stderr, "usage: tty [-s]\n");
78	exit(2);
79}