src/env.c

   1 /* env - run a program in a modified environment
   2    Copyright (C) 1986, 1991-2005, 2007-2010 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 <http://www.gnu.org/licenses/>.  */
  16
  17 /* Richard Mlynarik and David MacKenzie */
  18
  19 #include <config.h>
  20 #include <stdio.h>
  21 #include <sys/types.h>
  22 #include <getopt.h>
  23
  24 #include "system.h"
  25 #include "error.h"
  26 #include "quote.h"
  27
  28 /* The official name of this program (e.g., no `g' prefix).  */
  29 #define PROGRAM_NAME "env"
  30
  31 #define AUTHORS \
  32   proper_name ("Richard Mlynarik"), \
  33   proper_name ("David MacKenzie")
  34
  35 static struct option const longopts[] =
  36 {
  37   {"ignore-environment", no_argument, NULL, 'i'},
  38   {"null", no_argument, NULL, '0'},
  39   {"unset", required_argument, NULL, 'u'},
  40   {GETOPT_HELP_OPTION_DECL},
  41   {GETOPT_VERSION_OPTION_DECL},
  42   {NULL, 0, NULL, 0}
  43 };
  44
  45 void
  46 usage (int status)
  47 {
  48   if (status != EXIT_SUCCESS)
  49     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  50              program_name);
  51   else
  52     {
  53       printf (_("\
  54 Usage: %s [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n"),
  55               program_name);
  56       fputs (_("\
  57 Set each NAME to VALUE in the environment and run COMMAND.\n\
  58 \n\
  59   -i, --ignore-environment  start with an empty environment\n\
  60   -0, --null           end each output line with 0 byte rather than newline\n\
  61   -u, --unset=NAME     remove variable from the environment\n\
  62 "), stdout);
  63       fputs (HELP_OPTION_DESCRIPTION, stdout);
  64       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  65       fputs (_("\
  66 \n\
  67 A mere - implies -i.  If no COMMAND, print the resulting environment.\n\
  68 "), stdout);
  69       emit_ancillary_info ();
  70     }
  71   exit (status);
  72 }
  73
  74 int
  75 main (int argc, char **argv)
  76 {
  77   int optc;
  78   bool ignore_environment = false;
  79   bool opt_nul_terminate_output = false;
  80
  81   initialize_main (&argc, &argv);
  82   set_program_name (argv[0]);
  83   setlocale (LC_ALL, "");
  84   bindtextdomain (PACKAGE, LOCALEDIR);
  85   textdomain (PACKAGE);
  86
  87   initialize_exit_failure (EXIT_CANCELED);
  88   atexit (close_stdout);
  89
  90   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
  91     {
  92       switch (optc)
  93         {
  94         case 'i':
  95           ignore_environment = true;
  96           break;
  97         case 'u':
  98           break;
  99         case '0':
 100           opt_nul_terminate_output = true;
 101           break;
 102         case_GETOPT_HELP_CHAR;
 103         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 104         default:
 105           usage (EXIT_CANCELED);
 106         }
 107     }
 108
 109   if (optind < argc && STREQ (argv[optind], "-"))
 110     ignore_environment = true;
 111
 112   if (ignore_environment)
 113     {
 114       static char *dummy_environ[] = { NULL };
 115       environ = dummy_environ;
 116     }
 117
 118   optind = 0;                   /* Force GNU getopt to re-initialize. */
 119   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
 120     if (optc == 'u' && unsetenv (optarg))
 121       error (EXIT_CANCELED, errno, _("cannot unset %s"), quote (optarg));
 122
 123   if (optind < argc && STREQ (argv[optind], "-"))
 124     ++optind;
 125
 126   while (optind < argc && strchr (argv[optind], '='))
 127     if (putenv (argv[optind++]))
 128       {
 129         char *name = argv[optind - 1];
 130         *(strchr (name, '=')) = '\0';
 131         error (EXIT_CANCELED, errno, _("cannot set %s"), quote (name));
 132       }
 133
 134   /* If no program is specified, print the environment and exit. */
 135   if (argc <= optind)
 136     {
 137       char *const *e = environ;
 138       while (*e)
 139         printf ("%s%c", *e++, opt_nul_terminate_output ? '\0' : '\n');
 140       exit (EXIT_SUCCESS);
 141     }
 142
 143   if (opt_nul_terminate_output)
 144     {
 145       error (0, errno, _("cannot specify --null (-0) with command"));
 146       usage (EXIT_CANCELED);
 147     }
 148
 149   execvp (argv[optind], &argv[optind]);
 150
 151   {
 152     int exit_status = (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
 153     error (0, errno, "%s", argv[optind]);
 154     exit (exit_status);
 155   }
 156 }