1 /* printenv -- print all or part of environment
2 Copyright (C) 1989-2023 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 3 of the License, or
7 (at your option) 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, see <https://www.gnu.org/licenses/>. */
16
17 /* Usage: printenv [variable...]
18
19 If no arguments are given, print the entire environment.
20 If one or more variable names are given, print the value of
21 each one that is set, and nothing for ones that are not set.
22
23 Exit status:
24 0 if all variables specified were found
25 1 if not
26 2 if some other error occurred
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 "system.h"
36
37 /* Exit status for syntax errors, etc. */
38 enum { PRINTENV_FAILURE = 2 };
39
40 /* The official name of this program (e.g., no 'g' prefix). */
41 #define PROGRAM_NAME "printenv"
42
43 #define AUTHORS \
44 proper_name ("David MacKenzie"), \
45 proper_name ("Richard Mlynarik")
46
47 static struct option const longopts[] =
48 {
49 {"null", no_argument, nullptr, '0'},
50 {GETOPT_HELP_OPTION_DECL},
51 {GETOPT_VERSION_OPTION_DECL},
52 {nullptr, 0, nullptr, 0}
53 };
54
55 void
usage(int status)56 usage (int status)
57 {
58 if (status != EXIT_SUCCESS)
59 emit_try_help ();
60 else
61 {
62 printf (_("\
63 Usage: %s [OPTION]... [VARIABLE]...\n\
64 Print the values of the specified environment VARIABLE(s).\n\
65 If no VARIABLE is specified, print name and value pairs for them all.\n\
66 \n\
67 "),
68 program_name);
69 fputs (_("\
70 -0, --null end each output line with NUL, not newline\n\
71 "), stdout);
72 fputs (HELP_OPTION_DESCRIPTION, stdout);
73 fputs (VERSION_OPTION_DESCRIPTION, stdout);
74 printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
75 emit_ancillary_info (PROGRAM_NAME);
76 }
77 exit (status);
78 }
79
80 int
main(int argc,char ** argv)81 main (int argc, char **argv)
82 {
83 char **env;
84 char *ep, *ap;
85 int i;
86 bool ok;
87 int optc;
88 bool opt_nul_terminate_output = false;
89
90 initialize_main (&argc, &argv);
91 set_program_name (argv[0]);
92 setlocale (LC_ALL, "");
93 bindtextdomain (PACKAGE, LOCALEDIR);
94 textdomain (PACKAGE);
95
96 initialize_exit_failure (PRINTENV_FAILURE);
97 atexit (close_stdout);
98
99 while ((optc = getopt_long (argc, argv, "+iu:0", longopts, nullptr)) != -1)
100 {
101 switch (optc)
102 {
103 case '0':
104 opt_nul_terminate_output = true;
105 break;
106 case_GETOPT_HELP_CHAR;
107 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
108 default:
109 usage (PRINTENV_FAILURE);
110 }
111 }
112
113 if (optind >= argc)
114 {
115 for (env = environ; *env != nullptr; ++env)
116 printf ("%s%c", *env, opt_nul_terminate_output ? '\0' : '\n');
117 ok = true;
118 }
119 else
120 {
121 int matches = 0;
122
123 for (i = optind; i < argc; ++i)
124 {
125 bool matched = false;
126
127 /* 'printenv a=b' is silent, even if 'a=b=c' is in environ. */
128 if (strchr (argv[i], '='))
129 continue;
130
131 for (env = environ; *env; ++env)
132 {
133 ep = *env;
134 ap = argv[i];
135 while (*ep != '\0' && *ap != '\0' && *ep++ == *ap++)
136 {
137 if (*ep == '=' && *ap == '\0')
138 {
139 printf ("%s%c", ep + 1,
140 opt_nul_terminate_output ? '\0' : '\n');
141 matched = true;
142 break;
143 }
144 }
145 }
146
147 matches += matched;
148 }
149
150 ok = (matches == argc - optind);
151 }
152
153 return ok ? EXIT_SUCCESS : EXIT_FAILURE;
154 }
155