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 <sys/param.h>
33
34#include <err.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include <string.h>
38#include <unistd.h>
39
40static void usage(void) __dead2;
41
42int
43main(int argc, char *argv[])
44{
45	int ch, sflag, dflag;
46	char hostname[MAXHOSTNAMELEN], *hostp, *p;
47
48	sflag = 0;
49	dflag = 0;
50	while ((ch = getopt(argc, argv, "fsd")) != -1)
51		switch (ch) {
52		case 'f':
53			/*
54			 * On Linux, "hostname -f" prints FQDN.
55			 * BSD "hostname" always prints FQDN by
56			 * default, so we accept but ignore -f.
57			 */
58			break;
59		case 's':
60			sflag = 1;
61			break;
62		case 'd':
63			dflag = 1;
64			break;
65		case '?':
66		default:
67			usage();
68		}
69	argc -= optind;
70	argv += optind;
71
72	if (argc > 1 || (sflag && dflag))
73		usage();
74
75	if (*argv) {
76		if (sethostname(*argv, (int)strlen(*argv)))
77			err(1, "sethostname");
78	} else {
79		hostp = hostname;
80		if (gethostname(hostname, (int)sizeof(hostname)))
81			err(1, "gethostname");
82		if (sflag) {
83			p = strchr(hostname, '.');
84			if (p != NULL)
85				*p = '\0';
86		} else if (dflag) {
87			p = strchr(hostname, '.');
88			if (p != NULL)
89				hostp = p + 1;
90		}
91		(void)printf("%s\n", hostp);
92	}
93	exit(0);
94}
95
96static void
97usage(void)
98{
99
100	(void)fprintf(stderr, "usage: hostname [-f] [-s | -d] [name-of-host]\n");
101	exit(1);
102}
103