xref: /freebsd/usr.bin/tty/tty.c (revision 3e5d0784b9b5296bda801add034b057ad68237f7)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1988, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #ifndef lint
33 static const char copyright[] =
34 "@(#) Copyright (c) 1988, 1993\n\
35 	The Regents of the University of California.  All rights reserved.\n";
36 #endif /* not lint */
37 
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)tty.c	8.1 (Berkeley) 6/6/93";
41 #endif
42 #endif /* not lint */
43 
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD$");
46 
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <unistd.h>
50 
51 static void usage(void);
52 
53 int
54 main(int argc, char *argv[])
55 {
56 	int ch, sflag;
57 	char *t;
58 
59 	sflag = 0;
60 	while ((ch = getopt(argc, argv, "s")) != -1)
61 		switch (ch) {
62 		case 's':
63 			sflag = 1;
64 			break;
65 		case '?':
66 		default:
67 			usage();
68 			/* NOTREACHED */
69 		}
70 
71 	t = ttyname(STDIN_FILENO);
72 	if (!sflag)
73 		puts(t ? t : "not a tty");
74 	exit(t ? EXIT_SUCCESS : EXIT_FAILURE);
75 }
76 
77 static void
78 usage(void)
79 {
80 	fprintf(stderr, "usage: %s [-s]\n", getprogname());
81 	exit(2);
82 }
83