xref: /dragonfly/usr.bin/printenv/printenv.c (revision 71126e33)
1 /*
2  * Copyright (c) 1987, 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  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * @(#) Copyright (c) 1987, 1993 The Regents of the University of California.  All rights reserved.
34  * @(#)printenv.c	8.2 (Berkeley) 5/4/95
35  *
36  * $DragonFly: src/usr.bin/printenv/printenv.c,v 1.3 2003/10/04 20:36:50 hmp Exp $
37  */
38 
39 #include <sys/types.h>
40 
41 #include <stdlib.h>
42 #include <stdio.h>
43 #include <string.h>
44 #include <unistd.h>
45 
46 void	usage(void);
47 
48 /*
49  * printenv
50  *
51  * Bill Joy, UCB
52  * February, 1979
53  */
54 int
55 main(int argc, char **argv)
56 {
57 	extern char **environ;
58 	register char *cp, **ep;
59 	register size_t len;
60 	int ch;
61 
62 	while ((ch = getopt(argc, argv, "")) != -1)
63 		switch(ch) {
64 		case '?':
65 		default:
66 			usage();
67 		}
68 	argc -= optind;
69 	argv += optind;
70 
71 	if (argc == 0) {
72 		for (ep = environ; *ep; ep++)
73 			(void)printf("%s\n", *ep);
74 		exit(0);
75 	}
76 	len = strlen(*argv);
77 	for (ep = environ; *ep; ep++)
78 		if (!memcmp(*ep, *argv, len)) {
79 			cp = *ep + len;
80 			if (!*cp || *cp == '=') {
81 				(void)printf("%s\n", *cp ? cp + 1 : cp);
82 				exit(0);
83 			}
84 		}
85 	exit(1);
86 }
87 
88 void
89 usage(void)
90 {
91 	(void)fprintf(stderr, "usage: printenv [name]\n");
92 	exit(1);
93 }
94