usr.bin/printenv/printenv.c

   1 /*      $NetBSD: printenv.c,v 1.12 2011/09/06 18:26:55 joerg Exp $      */
   2
   3 /*
   4  * Copyright (c) 1987, 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/cdefs.h>
  33 #ifndef lint
  34 __COPYRIGHT("@(#) Copyright (c) 1987, 1993\
  35  The Regents of the University of California.  All rights reserved.");
  36 #endif /* not lint */
  37
  38 #ifndef lint
  39 /*static char sccsid[] = "from: @(#)printenv.c  8.2 (Berkeley) 5/4/95";*/
  40 __RCSID("$NetBSD: printenv.c,v 1.12 2011/09/06 18:26:55 joerg Exp $");
  41 #endif /* not lint */
  42
  43 #include <sys/types.h>
  44
  45 #include <stdlib.h>
  46 #include <stdio.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49 #include <err.h>
  50
  51 __dead static void usage(void);
  52
  53 /*
  54  * printenv
  55  *
  56  * Bill Joy, UCB
  57  * February, 1979
  58  */
  59 int
  60 main(int argc, char *argv[])
  61 {
  62         extern char **environ;
  63         char *cp, **ep;
  64         size_t len;
  65         int ch;
  66
  67         while ((ch = getopt(argc, argv, "")) != -1)
  68                 switch(ch) {
  69                 case '?':
  70                 default:
  71                         usage();
  72                 }
  73         argc -= optind;
  74         argv += optind;
  75
  76         if (argc == 0) {
  77                 for (ep = environ; *ep; ep++)
  78                         (void)printf("%s\n", *ep);
  79                 exit(0);
  80         }
  81         if (argc != 1)
  82                 usage();
  83         if (strchr(*argv, '=') != NULL)
  84                 errx(1, "Invalid environment variable %s", *argv);
  85         len = strlen(*argv);
  86         for (ep = environ; *ep; ep++)
  87                 if (!memcmp(*ep, *argv, len)) {
  88                         cp = *ep + len;
  89                         if (!*cp || *cp == '=') {
  90                                 (void)printf("%s\n", *cp ? cp + 1 : cp);
  91                                 exit(0);
  92                         }
  93                 }
  94         exit(1);
  95 }
  96
  97 static void
  98 usage(void)
  99 {
 100         (void)fprintf(stderr, "Usage: printenv [name]\n");
 101         exit(1);
 102 }