src/env.c

   1 /* env - run a program in a modified environment
   2    Copyright (C) 1986-2017 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   {"chdir", required_argument, NULL, 'C'},
  42   {GETOPT_HELP_OPTION_DECL},
  43   {GETOPT_VERSION_OPTION_DECL},
  44   {NULL, 0, NULL, 0}
  45 };
  46
  47 void
  48 usage (int status)
  49 {
  50   if (status != EXIT_SUCCESS)
  51     emit_try_help ();
  52   else
  53     {
  54       printf (_("\
  55 Usage: %s [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n"),
  56               program_name);
  57       fputs (_("\
  58 Set each NAME to VALUE in the environment and run COMMAND.\n\
  59 "), stdout);
  60
  61       emit_mandatory_arg_note ();
  62
  63       fputs (_("\
  64   -i, --ignore-environment  start with an empty environment\n\
  65   -0, --null           end each output line with NUL, not newline\n\
  66   -u, --unset=NAME     remove variable from the environment\n\
  67 "), stdout);
  68       fputs (_("\
  69   -C, --chdir=DIR      change working directory to DIR\n\
  70 "), stdout);
  71       fputs (HELP_OPTION_DESCRIPTION, stdout);
  72       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  73       fputs (_("\
  74 \n\
  75 A mere - implies -i.  If no COMMAND, print the resulting environment.\n\
  76 "), stdout);
  77       emit_ancillary_info (PROGRAM_NAME);
  78     }
  79   exit (status);
  80 }
  81
  82 int
  83 main (int argc, char **argv)
  84 {
  85   int optc;
  86   bool ignore_environment = false;
  87   bool opt_nul_terminate_output = false;
  88   char const *newdir = NULL;
  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 (EXIT_CANCELED);
  97   atexit (close_stdout);
  98
  99   while ((optc = getopt_long (argc, argv, "+C:iu:0", longopts, NULL)) != -1)
 100     {
 101       switch (optc)
 102         {
 103         case 'i':
 104           ignore_environment = true;
 105           break;
 106         case 'u':
 107           break;
 108         case '0':
 109           opt_nul_terminate_output = true;
 110           break;
 111         case 'C':
 112           newdir = optarg;
 113           break;
 114         case_GETOPT_HELP_CHAR;
 115         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 116         default:
 117           usage (EXIT_CANCELED);
 118         }
 119     }
 120
 121   if (optind < argc && STREQ (argv[optind], "-"))
 122     ignore_environment = true;
 123
 124   if (ignore_environment)
 125     {
 126       static char *dummy_environ[] = { NULL };
 127       environ = dummy_environ;
 128     }
 129
 130   optind = 0;                   /* Force GNU getopt to re-initialize. */
 131   while ((optc = getopt_long (argc, argv, "+C:iu:0", longopts, NULL)) != -1)
 132     if (optc == 'u' && unsetenv (optarg))
 133       die (EXIT_CANCELED, errno, _("cannot unset %s"), quote (optarg));
 134
 135   if (optind < argc && STREQ (argv[optind], "-"))
 136     ++optind;
 137
 138   char *eq;
 139   while (optind < argc && (eq = strchr (argv[optind], '=')))
 140     {
 141       if (putenv (argv[optind]))
 142         {
 143           *eq = '\0';
 144           die (EXIT_CANCELED, errno, _("cannot set %s"),
 145                quote (argv[optind]));
 146         }
 147       optind++;
 148     }
 149
 150   bool program_specified = optind < argc;
 151
 152   if (opt_nul_terminate_output && program_specified)
 153     {
 154       error (0, 0, _("cannot specify --null (-0) with command"));
 155       usage (EXIT_CANCELED);
 156     }
 157
 158   if (newdir && ! program_specified)
 159     {
 160       error (0, 0, _("must specify command with --chdir (-C)"));
 161       usage (EXIT_CANCELED);
 162     }
 163
 164   if (! program_specified)
 165     {
 166       /* Print the environment and exit. */
 167       char *const *e = environ;
 168       while (*e)
 169         printf ("%s%c", *e++, opt_nul_terminate_output ? '\0' : '\n');
 170       return EXIT_SUCCESS;
 171     }
 172
 173   if (newdir)
 174     {
 175       if (chdir (newdir) != 0)
 176         die (EXIT_CANCELED, errno, _("cannot change directory to %s"),
 177              quoteaf (newdir));
 178     }
 179
 180   execvp (argv[optind], &argv[optind]);
 181
 182   int exit_status = errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE;
 183   error (0, errno, "%s", quote (argv[optind]));
 184   return exit_status;
 185 }