usr.bin/printenv/printenv.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   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  * @(#)printenv.c       8.2 (Berkeley) 5/4/95
  32  * $FreeBSD: head/usr.bin/printenv/printenv.c 335395 2018-06-19 23:43:14Z oshogbo $
  33  */
  34
  35 #include <sys/types.h>
  36
  37 #include <err.h>
  38 #include <stdlib.h>
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42
  43 void    usage(void);
  44 extern char **environ;
  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         argc -= optind;
  66         argv += optind;
  67
  68         if (argc == 0) {
  69                 for (ep = environ; *ep; ep++)
  70                         printf("%s\n", *ep);
  71                 exit(0);
  72         }
  73         len = strlen(*argv);
  74         for (ep = environ; *ep; ep++)
  75                 if (!memcmp(*ep, *argv, len)) {
  76                         cp = *ep + len;
  77                         if (*cp == '=') {
  78                                 printf("%s\n", cp + 1);
  79                                 exit(0);
  80                         }
  81                 }
  82         exit(1);
  83 }
  84
  85 void
  86 usage(void)
  87 {
  88         fprintf(stderr, "usage: printenv [name]\n");
  89         exit(1);
  90 }