xref: /freebsd/usr.bin/tty/tty.c (revision 069ac18495ad8fde2748bc94b0f80a50250bb01d)
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  #include <stdio.h>
33  #include <stdlib.h>
34  #include <unistd.h>
35  
36  static void usage(void) __dead2;
37  
38  int
39  main(int argc, char *argv[])
40  {
41  	int ch, sflag;
42  	char *t;
43  
44  	sflag = 0;
45  	while ((ch = getopt(argc, argv, "s")) != -1)
46  		switch (ch) {
47  		case 's':
48  			sflag = 1;
49  			break;
50  		case '?':
51  		default:
52  			usage();
53  			/* NOTREACHED */
54  		}
55  
56  	t = ttyname(STDIN_FILENO);
57  	if (!sflag)
58  		puts(t ? t : "not a tty");
59  	exit(t ? EXIT_SUCCESS : EXIT_FAILURE);
60  }
61  
62  static void
63  usage(void)
64  {
65  	fprintf(stderr, "usage: %s [-s]\n", getprogname());
66  	exit(2);
67  }
68