src/printenv.c

   1 /* printenv -- print all or part of environment
   2    Copyright (C) 89, 90, 91, 92, 93, 94, 1995 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Usage: printenv [variable...]
  19
  20    If no arguments are given, print the entire environment.
  21    If one or more variable names are given, print the value of
  22    each one that is set, and nothing for ones that are not set.
  23
  24    Exit status:
  25    0 if all variables specified were found
  26    1 if not
  27
  28    David MacKenzie and Richard Mlynarik */
  29
  30 #include <config.h>
  31 #include <stdio.h>
  32 #include <sys/types.h>
  33 #include <getopt.h>
  34
  35 #include "version.h"
  36 #include "system.h"
  37 #include "error.h"
  38
  39 /* The name this program was run with. */
  40 char *program_name;
  41
  42 /* If non-zero, display usage information and exit.  */
  43 static int show_help;
  44
  45 /* If non-zero, print the version on standard output and exit.  */
  46 static int show_version;
  47
  48 static struct option const long_options[] =
  49 {
  50   {"help", no_argument, &show_help, 1},
  51   {"version", no_argument, &show_version, 1},
  52   {0, 0, 0, 0}
  53 };
  54
  55 extern char **environ;
  56
  57 static void
  58 usage (status)
  59      int status;
  60 {
  61   if (status != 0)
  62     fprintf (stderr, "Try `%s --help' for more information.\n",
  63              program_name);
  64   else
  65     {
  66       printf ("Usage: %s [OPTION]... [VARIABLE]...\n", program_name);
  67       printf ("\
  68 If no environment VARIABLE specified, print them all.\n\
  69 \n\
  70   --help      display this help and exit\n\
  71   --version   output version information and exit\n");
  72     }
  73   exit (status);
  74 }
  75
  76 void
  77 main (argc, argv)
  78      int argc;
  79      char **argv;
  80 {
  81   char **env;
  82   char *ep, *ap;
  83   int i;
  84   int matches = 0;
  85   int c;
  86   int exit_status;
  87
  88   program_name = argv[0];
  89
  90   while ((c = getopt_long (argc, argv, "", long_options, (int *) 0)) != EOF)
  91     {
  92       switch (c)
  93         {
  94         case 0:
  95           break;
  96
  97         default:
  98           usage (1);
  99         }
 100     }
 101
 102   if (show_version)
 103     {
 104       printf ("printenv - %s\n", version_string);
 105       exit (0);
 106     }
 107
 108   if (show_help)
 109     usage (0);
 110
 111   if (optind == argc)
 112     {
 113       for (env = environ; *env != NULL; ++env)
 114         puts (*env);
 115       exit_status = 0;
 116     }
 117   else
 118     {
 119       for (i = optind; i < argc; ++i)
 120         {
 121           for (env = environ; *env; ++env)
 122             {
 123               ep = *env;
 124               ap = argv[i];
 125               while (*ep != '\0' && *ap != '\0' && *ep++ == *ap++)
 126                 {
 127                   if (*ep == '=' && *ap == '\0')
 128                     {
 129                       puts (ep + 1);
 130                       ++matches;
 131                       break;
 132                     }
 133                 }
 134             }
 135         }
 136       exit_status = (matches != argc - optind);
 137     }
 138
 139   if (ferror (stdout) || fclose (stdout) == EOF)
 140     error (2, errno, "standard output");
 141
 142   exit (exit_status);
 143 }