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 "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 "), stdout);
  58
  59       emit_mandatory_arg_note ();
  60
  61       fputs (_("\
  62   -i, --ignore-environment  start with an empty environment\n\
  63   -0, --null           end each output line with NUL, not newline\n\
  64   -u, --unset=NAME     remove variable from the environment\n\
  65 "), stdout);
  66       fputs (HELP_OPTION_DESCRIPTION, stdout);
  67       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  68       fputs (_("\
  69 \n\
  70 A mere - implies -i.  If no COMMAND, print the resulting environment.\n\
  71 "), stdout);
  72       emit_ancillary_info (PROGRAM_NAME);
  73     }
  74   exit (status);
  75 }
  76
  77 int
  78 main (int argc, char **argv)
  79 {
  80   int optc;
  81   bool ignore_environment = false;
  82   bool opt_nul_terminate_output = false;
  83
  84   initialize_main (&argc, &argv);
  85   set_program_name (argv[0]);
  86   setlocale (LC_ALL, "");
  87   bindtextdomain (PACKAGE, LOCALEDIR);
  88   textdomain (PACKAGE);
  89
  90   initialize_exit_failure (EXIT_CANCELED);
  91   atexit (close_stdout);
  92
  93   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
  94     {
  95       switch (optc)
  96         {
  97         case 'i':
  98           ignore_environment = true;
  99           break;
 100         case 'u':
 101           break;
 102         case '0':
 103           opt_nul_terminate_output = true;
 104           break;
 105         case_GETOPT_HELP_CHAR;
 106         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 107         default:
 108           usage (EXIT_CANCELED);
 109         }
 110     }
 111
 112   if (optind < argc && STREQ (argv[optind], "-"))
 113     ignore_environment = true;
 114
 115   if (ignore_environment)
 116     {
 117       static char *dummy_environ[] = { NULL };
 118       environ = dummy_environ;
 119     }
 120
 121   optind = 0;                   /* Force GNU getopt to re-initialize. */
 122   while ((optc = getopt_long (argc, argv, "+iu:0", longopts, NULL)) != -1)
 123     if (optc == 'u' && unsetenv (optarg))
 124       error (EXIT_CANCELED, errno, _("cannot unset %s"), quote (optarg));
 125
 126   if (optind < argc && STREQ (argv[optind], "-"))
 127     ++optind;
 128
 129   char *eq;
 130   while (optind < argc && (eq = strchr (argv[optind], '=')))
 131     {
 132       if (putenv (argv[optind]))
 133         {
 134           *eq = '\0';
 135           error (EXIT_CANCELED, errno, _("cannot set %s"),
 136                  quote (argv[optind]));
 137         }
 138       optind++;
 139     }
 140
 141   /* If no program is specified, print the environment and exit. */
 142   if (argc <= optind)
 143     {
 144       char *const *e = environ;
 145       while (*e)
 146         printf ("%s%c", *e++, opt_nul_terminate_output ? '\0' : '\n');
 147       return EXIT_SUCCESS;
 148     }
 149
 150   if (opt_nul_terminate_output)
 151     {
 152       error (0, errno, _("cannot specify --null (-0) with command"));
 153       usage (EXIT_CANCELED);
 154     }
 155
 156   execvp (argv[optind], &argv[optind]);
 157
 158   int exit_status = errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE;
 159   error (0, errno, "%s", quote (argv[optind]));
 160   return exit_status;
 161 }