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. 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 1.4 2005/01/07 02:32:50 cpressey 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 extern char **environ;
  47
  48 static void     usage(void);
  49
  50 /*
  51  * printenv
  52  *
  53  * Bill Joy, UCB
  54  * February, 1979
  55  */
  56 int
  57 main(int argc, char **argv)
  58 {
  59         char *cp, **ep;
  60         size_t len;
  61         int ch;
  62
  63         while ((ch = getopt(argc, argv, "")) != -1) {
  64                 switch(ch) {
  65                 case '?':
  66                 default:
  67                         usage();
  68                 }
  69         }
  70         argc -= optind;
  71         argv += optind;
  72
  73         if (argc == 0) {
  74                 for (ep = environ; *ep != NULL; ep++)
  75                         printf("%s\n", *ep);
  76                 exit(0);
  77         }
  78         len = strlen(*argv);
  79         for (ep = environ; *ep != NULL; ep++) {
  80                 cp = strchr(*ep, '=');
  81                 if (cp == *ep + len) {
  82                         if (memcmp(*ep, *argv, len) == 0) {
  83                                 printf("%s\n", cp + 1);
  84                                 exit(0);
  85                         }
  86                 }
  87         }
  88         exit(1);
  89 }
  90
  91 static void
  92 usage(void)
  93 {
  94         fprintf(stderr, "usage: printenv [name]\n");
  95         exit(1);
  96 }