src/env.c

   1 /* env - run a program in a modified environment
   2    Copyright (C) 1986-2012 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     emit_try_help ();
  50   else
  51     {
  52       printf (_("\
  53 Usage: %s [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n"),
  54               program_name);
  55       fputs (_("\
  56 Set each NAME to VALUE in the environment and run COMMAND.\n\
  57 \n\
  58   -i, --ignore-environment  start with an empty environment\n\
  59   -0, --null           end each output line with 0 byte rather than newline\n\
  60   -u, --unset=NAME     remove variable from the environment\n\
  61 "), stdout);
  62       fputs (HELP_OPTION_DESCRIPTION, stdout);
  63       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  64       fputs (_("\
  65 \n\
  66 A mere - implies -i.  If no COMMAND, print the resulting environment.\n\
  67 "), stdout);
  68       emit_ancillary_info ();
  69     }
  70   exit (status);
  71 }
  72
  73 int
  74 main (int argc, char **argv)
  75 {
  76   int optc;
  77   bool ignore_environment = false;
  78   bool opt_nul_terminate_output = false;
  79
  80   initialize_main (&argc, &argv);
  81   set_program_name (argv[0]);
  82   setlocale (LC_ALL, "");
  83   bindtextdomain (PACKAGE, LOCALEDIR);
  84   textdomain (PACKAGE);
  85
  86   initialize_exit_failure (EXIT_CANCELED);
  87   atexit (close_stdout);
  88
  89   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
  90     {
  91       switch (optc)
  92         {
  93         case 'i':
  94           ignore_environment = true;
  95           break;
  96         case 'u':
  97           break;
  98         case '0':
  99           opt_nul_terminate_output = true;
 100           break;
 101         case_GETOPT_HELP_CHAR;
 102         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 103         default:
 104           usage (EXIT_CANCELED);
 105         }
 106     }
 107
 108   if (optind < argc && STREQ (argv[optind], "-"))
 109     ignore_environment = true;
 110
 111   if (ignore_environment)
 112     {
 113       static char *dummy_environ[] = { NULL };
 114       environ = dummy_environ;
 115     }
 116
 117   optind = 0;                   /* Force GNU getopt to re-initialize. */
 118   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
 119     if (optc == 'u' && unsetenv (optarg))
 120       error (EXIT_CANCELED, errno, _("cannot unset %s"), quote (optarg));
 121
 122   if (optind < argc && STREQ (argv[optind], "-"))
 123     ++optind;
 124
 125   char *eq;
 126   while (optind < argc && (eq = strchr (argv[optind], '=')))
 127     {
 128       if (putenv (argv[optind]))
 129         {
 130           *eq = '\0';
 131           error (EXIT_CANCELED, errno, _("cannot set %s"),
 132                  quote (argv[optind]));
 133         }
 134       optind++;
 135     }
 136
 137   /* If no program is specified, print the environment and exit. */
 138   if (argc <= optind)
 139     {
 140       char *const *e = environ;
 141       while (*e)
 142         printf ("%s%c", *e++, opt_nul_terminate_output ? '\0' : '\n');
 143       exit (EXIT_SUCCESS);
 144     }
 145
 146   if (opt_nul_terminate_output)
 147     {
 148       error (0, errno, _("cannot specify --null (-0) with command"));
 149       usage (EXIT_CANCELED);
 150     }
 151
 152   execvp (argv[optind], &argv[optind]);
 153
 154   {
 155     int exit_status = (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
 156     error (0, errno, "%s", argv[optind]);
 157     exit (exit_status);
 158   }
 159 }