src/env.c

   1 /* env - run a program in a modified environment
   2    Copyright (C) 1986-2016 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 "die.h"
  26 #include "error.h"
  27 #include "quote.h"
  28
  29 /* The official name of this program (e.g., no 'g' prefix).  */
  30 #define PROGRAM_NAME "env"
  31
  32 #define AUTHORS \
  33   proper_name ("Richard Mlynarik"), \
  34   proper_name ("David MacKenzie")
  35
  36 static struct option const longopts[] =
  37 {
  38   {"ignore-environment", no_argument, NULL, 'i'},
  39   {"null", no_argument, NULL, '0'},
  40   {"unset", required_argument, NULL, 'u'},
  41   {GETOPT_HELP_OPTION_DECL},
  42   {GETOPT_VERSION_OPTION_DECL},
  43   {NULL, 0, NULL, 0}
  44 };
  45
  46 void
  47 usage (int status)
  48 {
  49   if (status != EXIT_SUCCESS)
  50     emit_try_help ();
  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 "), stdout);
  59
  60       emit_mandatory_arg_note ();
  61
  62       fputs (_("\
  63   -i, --ignore-environment  start with an empty environment\n\
  64   -0, --null           end each output line with NUL, not newline\n\
  65   -u, --unset=NAME     remove variable from the environment\n\
  66 "), stdout);
  67       fputs (HELP_OPTION_DESCRIPTION, stdout);
  68       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  69       fputs (_("\
  70 \n\
  71 A mere - implies -i.  If no COMMAND, print the resulting environment.\n\
  72 "), stdout);
  73       emit_ancillary_info (PROGRAM_NAME);
  74     }
  75   exit (status);
  76 }
  77
  78 int
  79 main (int argc, char **argv)
  80 {
  81   int optc;
  82   bool ignore_environment = false;
  83   bool opt_nul_terminate_output = false;
  84
  85   initialize_main (&argc, &argv);
  86   set_program_name (argv[0]);
  87   setlocale (LC_ALL, "");
  88   bindtextdomain (PACKAGE, LOCALEDIR);
  89   textdomain (PACKAGE);
  90
  91   initialize_exit_failure (EXIT_CANCELED);
  92   atexit (close_stdout);
  93
  94   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
  95     {
  96       switch (optc)
  97         {
  98         case 'i':
  99           ignore_environment = true;
 100           break;
 101         case 'u':
 102           break;
 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 (EXIT_CANCELED);
 110         }
 111     }
 112
 113   if (optind < argc && STREQ (argv[optind], "-"))
 114     ignore_environment = true;
 115
 116   if (ignore_environment)
 117     {
 118       static char *dummy_environ[] = { NULL };
 119       environ = dummy_environ;
 120     }
 121
 122   optind = 0;                   /* Force GNU getopt to re-initialize. */
 123   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
 124     if (optc == 'u' && unsetenv (optarg))
 125       die (EXIT_CANCELED, errno, _("cannot unset %s"), quote (optarg));
 126
 127   if (optind < argc && STREQ (argv[optind], "-"))
 128     ++optind;
 129
 130   char *eq;
 131   while (optind < argc && (eq = strchr (argv[optind], '=')))
 132     {
 133       if (putenv (argv[optind]))
 134         {
 135           *eq = '\0';
 136           die (EXIT_CANCELED, errno, _("cannot set %s"),
 137                quote (argv[optind]));
 138         }
 139       optind++;
 140     }
 141
 142   /* If no program is specified, print the environment and exit. */
 143   if (argc <= optind)
 144     {
 145       char *const *e = environ;
 146       while (*e)
 147         printf ("%s%c", *e++, opt_nul_terminate_output ? '\0' : '\n');
 148       return EXIT_SUCCESS;
 149     }
 150
 151   if (opt_nul_terminate_output)
 152     {
 153       error (0, errno, _("cannot specify --null (-0) with command"));
 154       usage (EXIT_CANCELED);
 155     }
 156
 157   execvp (argv[optind], &argv[optind]);
 158
 159   int exit_status = errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE;
 160   error (0, errno, "%s", quote (argv[optind]));
 161   return exit_status;
 162 }