xref: /freebsd/usr.bin/printenv/printenv.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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 
34 #ifndef lint
35 static const char copyright[] =
36 "@(#) Copyright (c) 1987, 1993\n\
37 	The Regents of the University of California.  All rights reserved.\n";
38 #endif /* not lint */
39 
40 #if 0
41 #ifndef lint
42 static char sccsid[] = "@(#)printenv.c	8.2 (Berkeley) 5/4/95";
43 #endif /* not lint */
44 #endif
45 
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD$");
48 
49 #include <sys/types.h>
50 
51 #include <stdlib.h>
52 #include <stdio.h>
53 #include <string.h>
54 #include <unistd.h>
55 
56 void	usage(void);
57 
58 /*
59  * printenv
60  *
61  * Bill Joy, UCB
62  * February, 1979
63  */
64 int
65 main(int argc, char *argv[])
66 {
67 	extern char **environ;
68 	char *cp, **ep;
69 	size_t len;
70 	int ch;
71 
72 	while ((ch = getopt(argc, argv, "")) != -1)
73 		switch(ch) {
74 		case '?':
75 		default:
76 			usage();
77 		}
78 	argc -= optind;
79 	argv += optind;
80 
81 	if (argc == 0) {
82 		for (ep = environ; *ep; ep++)
83 			(void)printf("%s\n", *ep);
84 		exit(0);
85 	}
86 	len = strlen(*argv);
87 	for (ep = environ; *ep; ep++)
88 		if (!memcmp(*ep, *argv, len)) {
89 			cp = *ep + len;
90 			if (!*cp || *cp == '=') {
91 				(void)printf("%s\n", *cp ? cp + 1 : cp);
92 				exit(0);
93 			}
94 		}
95 	exit(1);
96 }
97 
98 void
99 usage(void)
100 {
101 	(void)fprintf(stderr, "usage: printenv [name]\n");
102 	exit(1);
103 }
104