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