src/env.c

   1 /* env - run a program in a modified environment
   2    Copyright (C) 1986, 1991-2000 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 2, or (at your option)
   7    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, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Richard Mlynarik and David MacKenzie */
  19
  20 /* Options:
  21    -
  22    -i
  23    --ignore-environment
  24         Construct a new environment from scratch; normally the
  25         environment is inherited from the parent process, except as
  26         modified by other options.
  27
  28    -u variable
  29    --unset=variable
  30         Unset variable VARIABLE (remove it from the environment).
  31         If VARIABLE was not set, does nothing.
  32
  33    variable=value (an arg containing a "=" character)
  34         Set the environment variable VARIABLE to value VALUE.  VALUE
  35         may be of zero length ("variable=").  Setting a variable to a
  36         zero-length value is different from unsetting it.
  37
  38    --
  39         Indicate that the following argument is the program
  40         to invoke.  This is necessary when the program's name
  41         begins with "-" or contains a "=".
  42
  43    The first remaining argument specifies a program to invoke;
  44    it is searched for according to the specification of the PATH
  45    environment variable.  Any arguments following that are
  46    passed as arguments to that program.
  47
  48    If no command name is specified following the environment
  49    specifications, the resulting environment is printed.
  50    This is like specifying a command name of "printenv".
  51
  52    Examples:
  53
  54    If the environment passed to "env" is
  55         { LOGNAME=rms EDITOR=emacs PATH=.:/gnubin:/hacks }
  56
  57    env - foo
  58         runs "foo" in a null environment.
  59
  60    env foo
  61         runs "foo" in the environment
  62         { LOGNAME=rms EDITOR=emacs PATH=.:/gnubin:/hacks }
  63
  64    env DISPLAY=gnu:0 nemacs
  65         runs "nemacs" in the envionment
  66         { LOGNAME=rms EDITOR=emacs PATH=.:/gnubin:/hacks DISPLAY=gnu:0 }
  67
  68    env - LOGNAME=foo /hacks/hack bar baz
  69         runs the "hack" program on arguments "bar" and "baz" in an
  70         environment in which the only variable is "LOGNAME".  Note that
  71         the "-" option clears out the PATH variable, so one should be
  72         careful to specify in which directory to find the program to
  73         call.
  74
  75    env -u EDITOR LOGNAME=foo PATH=/energy -- e=mc2 bar baz
  76         runs the program "/energy/e=mc2" with environment
  77         { LOGNAME=foo PATH=/energy }
  78 */
  79
  80 #include <config.h>
  81 #include <stdio.h>
  82 #include <getopt.h>
  83 #include <sys/types.h>
  84 #include <getopt.h>
  85
  86 #include "system.h"
  87 #include "error.h"
  88 #include "closeout.h"
  89
  90 /* The official name of this program (e.g., no `g' prefix).  */
  91 #define PROGRAM_NAME "env"
  92
  93 #define AUTHORS "Richard Mlynarik and David MacKenzie"
  94
  95 int putenv ();
  96
  97 extern char **environ;
  98
  99 /* The name by which this program was run. */
 100 char *program_name;
 101
 102 static struct option const longopts[] =
 103 {
 104   {"ignore-environment", no_argument, NULL, 'i'},
 105   {"unset", required_argument, NULL, 'u'},
 106   {GETOPT_HELP_OPTION_DECL},
 107   {GETOPT_VERSION_OPTION_DECL},
 108   {NULL, 0, NULL, 0}
 109 };
 110
 111 void
 112 usage (int status)
 113 {
 114   if (status != 0)
 115     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 116              program_name);
 117   else
 118     {
 119       printf (_("\
 120 Usage: %s [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n"),
 121               program_name);
 122       printf (_("\
 123 Set each NAME to VALUE in the environment and run COMMAND.\n\
 124 \n\
 125   -i, --ignore-environment   start with an empty environment\n\
 126   -u, --unset=NAME           remove variable from the environment\n\
 127       --help                 display this help and exit\n\
 128       --version              output version information and exit\n\
 129 \n\
 130 A mere - implies -i.  If no COMMAND, print the resulting environment.\n\
 131 "));
 132       puts (_("\nReport bugs to <bug-sh-utils@gnu.org>."));
 133     }
 134   exit (status);
 135 }
 136
 137 int
 138 main (register int argc, register char **argv, char **envp)
 139 {
 140   char *dummy_environ[1];
 141   int optc;
 142   int ignore_environment = 0;
 143
 144   program_name = argv[0];
 145   setlocale (LC_ALL, "");
 146   bindtextdomain (PACKAGE, LOCALEDIR);
 147   textdomain (PACKAGE);
 148
 149   atexit (close_stdout);
 150
 151   while ((optc = getopt_long (argc, argv, "+iu:", longopts, NULL)) != -1)
 152     {
 153       switch (optc)
 154         {
 155         case 0:
 156           break;
 157         case 'i':
 158           ignore_environment = 1;
 159           break;
 160         case 'u':
 161           break;
 162         case_GETOPT_HELP_CHAR;
 163         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 164         default:
 165           usage (2);
 166         }
 167     }
 168
 169   if (optind != argc && !strcmp (argv[optind], "-"))
 170     ignore_environment = 1;
 171
 172   environ = dummy_environ;
 173   environ[0] = NULL;
 174
 175   if (!ignore_environment)
 176     for (; *envp; envp++)
 177       putenv (*envp);
 178
 179   optind = 0;                   /* Force GNU getopt to re-initialize. */
 180   while ((optc = getopt_long (argc, argv, "+iu:", longopts, NULL)) != -1)
 181     if (optc == 'u')
 182       putenv (optarg);          /* Requires GNU putenv. */
 183
 184   if (optind != argc && !strcmp (argv[optind], "-"))
 185     ++optind;
 186
 187   while (optind < argc && strchr (argv[optind], '='))
 188     putenv (argv[optind++]);
 189
 190   /* If no program is specified, print the environment and exit. */
 191   if (optind == argc)
 192     {
 193       while (*environ)
 194         puts (*environ++);
 195       exit (0);
 196     }
 197
 198   execvp (argv[optind], &argv[optind]);
 199
 200   {
 201     int exit_status = (errno == ENOENT ? 127 : 126);
 202     error (0, errno, "%s", argv[optind]);
 203     exit (exit_status);
 204   }
 205 }