summaryrefslogtreecommitdiff
path: root/src/printenv.c
blob: de2b58f286de3fd78a8f1ddfbce3ab1352a12a17 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
/* printenv -- print all or part of environment
   Copyright (C) 1989-1997, 1999-2005, 2007-2011 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Usage: printenv [variable...]

   If no arguments are given, print the entire environment.
   If one or more variable names are given, print the value of
   each one that is set, and nothing for ones that are not set.

   Exit status:
   0 if all variables specified were found
   1 if not
   2 if some other error occurred

   David MacKenzie and Richard Mlynarik */

#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <getopt.h>

#include "system.h"

/* Exit status for syntax errors, etc.  */
enum { PRINTENV_FAILURE = 2 };

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "printenv"

#define AUTHORS \
  proper_name ("David MacKenzie"), \
  proper_name ("Richard Mlynarik")

static struct option const longopts[] =
{
  {"null", no_argument, NULL, '0'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
             program_name);
  else
    {
      printf (_("\
Usage: %s [OPTION]... [VARIABLE]...\n\
Print the values of the specified environment VARIABLE(s).\n\
If no VARIABLE is specified, print name and value pairs for them all.\n\
\n\
"),
              program_name);
      fputs (_("\
  -0, --null     end each output line with 0 byte rather than newline\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
      emit_ancillary_info ();
    }
  exit (status);
}

int
main (int argc, char **argv)
{
  char **env;
  char *ep, *ap;
  int i;
  bool ok;
  int optc;
  bool opt_nul_terminate_output = false;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  initialize_exit_failure (PRINTENV_FAILURE);
  atexit (close_stdout);

  while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
    {
      switch (optc)
        {
        case '0':
          opt_nul_terminate_output = true;
          break;
        case_GETOPT_HELP_CHAR;
        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
        default:
          usage (PRINTENV_FAILURE);
        }
    }

  if (optind >= argc)
    {
      for (env = environ; *env != NULL; ++env)
        printf ("%s%c", *env, opt_nul_terminate_output ? '\0' : '\n');
      ok = true;
    }
  else
    {
      int matches = 0;

      for (i = optind; i < argc; ++i)
        {
          bool matched = false;

          /* 'printenv a=b' is silent, even if 'a=b=c' is in environ.  */
          if (strchr (argv[i], '='))
            continue;

          for (env = environ; *env; ++env)
            {
              ep = *env;
              ap = argv[i];
              while (*ep != '\0' && *ap != '\0' && *ep++ == *ap++)
                {
                  if (*ep == '=' && *ap == '\0')
                    {
                      printf ("%s%c", ep + 1,
                              opt_nul_terminate_output ? '\0' : '\n');
                      matched = true;
                      break;
                    }
                }
            }

          matches += matched;
        }

      ok = (matches == argc - optind);
    }

  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}