xref: /freebsd/bin/hostname/hostname.c (revision 5e3190f700637fcfc1a52daeaa4a031fdd2557c7)
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 #if 0
33 #ifndef lint
34 static char const copyright[] =
35 "@(#) Copyright (c) 1988, 1993\n\
36 	The Regents of the University of California.  All rights reserved.\n";
37 #endif /* not lint */
38 
39 #ifndef lint
40 static char sccsid[] = "@(#)hostname.c	8.1 (Berkeley) 5/31/93";
41 #endif /* not lint */
42 #endif
43 #include <sys/cdefs.h>
44 #include <sys/param.h>
45 
46 #include <err.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50 #include <unistd.h>
51 
52 static void usage(void) __dead2;
53 
54 int
55 main(int argc, char *argv[])
56 {
57 	int ch, sflag, dflag;
58 	char hostname[MAXHOSTNAMELEN], *hostp, *p;
59 
60 	sflag = 0;
61 	dflag = 0;
62 	while ((ch = getopt(argc, argv, "fsd")) != -1)
63 		switch (ch) {
64 		case 'f':
65 			/*
66 			 * On Linux, "hostname -f" prints FQDN.
67 			 * BSD "hostname" always prints FQDN by
68 			 * default, so we accept but ignore -f.
69 			 */
70 			break;
71 		case 's':
72 			sflag = 1;
73 			break;
74 		case 'd':
75 			dflag = 1;
76 			break;
77 		case '?':
78 		default:
79 			usage();
80 		}
81 	argc -= optind;
82 	argv += optind;
83 
84 	if (argc > 1 || (sflag && dflag))
85 		usage();
86 
87 	if (*argv) {
88 		if (sethostname(*argv, (int)strlen(*argv)))
89 			err(1, "sethostname");
90 	} else {
91 		hostp = hostname;
92 		if (gethostname(hostname, (int)sizeof(hostname)))
93 			err(1, "gethostname");
94 		if (sflag) {
95 			p = strchr(hostname, '.');
96 			if (p != NULL)
97 				*p = '\0';
98 		} else if (dflag) {
99 			p = strchr(hostname, '.');
100 			if (p != NULL)
101 				hostp = p + 1;
102 		}
103 		(void)printf("%s\n", hostp);
104 	}
105 	exit(0);
106 }
107 
108 static void
109 usage(void)
110 {
111 
112 	(void)fprintf(stderr, "usage: hostname [-f] [-s | -d] [name-of-host]\n");
113 	exit(1);
114 }
115