usr.bin/printenv/printenv.c

   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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#) Copyright (c) 1987, 1993 The Regents of the University of California.  All rights reserved.
  30  * @(#)printenv.c       8.2 (Berkeley) 5/4/95
  31  *
  32  * $DragonFly: src/usr.bin/printenv/printenv.c,v 1.4 2005/01/07 02:32:50 cpressey Exp $
  33  */
  34
  35 #include <sys/types.h>
  36
  37 #include <stdlib.h>
  38 #include <stdio.h>
  39 #include <string.h>
  40 #include <unistd.h>
  41
  42 extern char **environ;
  43
  44 static void     usage(void);
  45
  46 /*
  47  * printenv
  48  *
  49  * Bill Joy, UCB
  50  * February, 1979
  51  */
  52 int
  53 main(int argc, char **argv)
  54 {
  55         char *cp, **ep;
  56         size_t len;
  57         int ch;
  58
  59         while ((ch = getopt(argc, argv, "")) != -1) {
  60                 switch(ch) {
  61                 case '?':
  62                 default:
  63                         usage();
  64                 }
  65         }
  66         argc -= optind;
  67         argv += optind;
  68
  69         if (argc == 0) {
  70                 for (ep = environ; *ep != NULL; ep++)
  71                         printf("%s\n", *ep);
  72                 exit(0);
  73         }
  74         len = strlen(*argv);
  75         for (ep = environ; *ep != NULL; ep++) {
  76                 cp = strchr(*ep, '=');
  77                 if (cp == *ep + len) {
  78                         if (memcmp(*ep, *argv, len) == 0) {
  79                                 printf("%s\n", cp + 1);
  80                                 exit(0);
  81                         }
  82                 }
  83         }
  84         exit(1);
  85 }
  86
  87 static void
  88 usage(void)
  89 {
  90         fprintf(stderr, "usage: printenv [name]\n");
  91         exit(1);
  92 }